Journal Papers


  1. G. Q. Li†, X. Zhao†, X. Tang, L. Yao, W. Y. Li, J. W. Wang, X. J. Liu, B. Han, X. C. Fan, T. Qiu*, and Q. Hao*, “Wearable Hydrogel SERS Chip Utilizing Plasmonic Trimers for Uric Acid Analysis in Sweat”, Nano Letters, vol. 24, iss. 24, pp. 13447-13454 (2024).  († Contributed Equally)  [Highlighted by ACS材料X]



    Uric acid is typically measured through blood tests, which can be inconvenient and uncomfortable for patients. Herein, we propose a wearable surface-enhanced Raman scattering (SERS) chip, incorporating a hydrogel membrane with integrated plasmonic trimers, for noninvasive monitoring of uric acid in sweat. The plasmonic trimers feature sub 5 nm nanogaps, generating strong electromagnetic fields to boost the Raman signal of surrounding molecules. Simultaneously, the hydrogel membrane pumps sweat through these gaps, efficiently capturing sweat biomarkers for SERS detection. The chip can achieve saturation adsorption of sweat within 5 min, eliminating variations in individual sweat production rates. Dynamic SERS tracking of uric acid and lactic acid levels during anaerobic exercise reveals a temporary suppression of uric acid metabolism, likely due to metabolic competition with lactic acid. Furthermore, long-term monitoring correlates well with blood test results, confirming that regular exercise helps reduce serum uric acid levels and supporting its potential in managing hyperuricemia.

  2. Y. J. Wei, D. X. Chen, X. C. Fan, X. Tang, L. Yao, X. Zhao, Q. Li, J. W. Wang, T. Qiu, and Q. Hao*, “Unveiling Plasmon-Induced Suzuki–Miyaura Reactions on Silver Nanoparticles via Raman Spectroscopy”, ACS Catalysis, vol. 14, iss. 20, pp. 15043–15051 (2024).  [Highlighted by ACS美国化学会]



    The Suzuki–Miyaura coupling reaction is an efficient organic method for synthesizing biphenyl products. However, its conventional reliance on toxic soluble organometallic palladium catalysts or expensive palladium nanoparticles, along with the need for elevated temperatures and prolonged reaction times, presents a significant challenge. Herein, we demonstrate a palladium-free approach using plasmonic silver nanoparticles that enables the Suzuki–Miyaura coupling reaction to proceed at room temperature under visible light. Utilizing the surface-enhanced Raman scattering characteristics of silver, we conducted dynamic self-monitoring of the reaction. Our findings reveal that this plasmon-induced Suzuki–Miyaura coupling reaction fundamentally operates as a heterogeneous reaction involving coupling between radicals, distinct from conventional palladium-based reactions. Moreover, the cleavage of C–Cl and C–B bonds, fundamental prerequisite to the coupling, is driven by plasmonic hot electrons and plasmon-induced reactive oxygen species, respectively. These findings not only provide insights into the design and regulation of plasmonic catalysts but also enhance theoretical understanding of the Suzuki–Miyaura reaction in a broader context.

  3. L. L. Lan, Z. H. Ni, C. Y. Zhao*, J. Gao, X. Tang, Z. W. Qu, L. C. Zheng, X. C. Fan*, and T. Qiu*, “Photoinduced Charge Transfer Empowers Ta4C3 and Nb4C3 MXenes with High SERS Performance”, Langmuir, vol. 40, iss. 40, pp. 20945-20953 (2024).



    This study introduces two-dimensional (2D) Ta4C3 and Nb4C3 MXenes as outstanding materials for surface-enhanced Raman scattering (SERS) sensing, marking a significant departure from traditional noble-metal substrates. These MXenes exhibit exceptional SERS capabilities, achieving enhancement factors around 105 and detection limits as low as 10-7 M for various analytes, including environmental pollutants and drugs. The core of their SERS functionality is attributed to the robust interfacial photoinduced charge-transfer interactions between the MXenes and the adsorbed molecules. This deep insight not only advances our understanding of MXene materials in SERS applications but also opens new avenues for developing highly sensitive and selective SERS sensors. The potential of Ta4C3 and Nb4C3 MXenes to revolutionize SERS technology underscores their importance in environmental monitoring, food safety, and beyond.

  4. X. Zhao†, X. J. Liu†, D. X. Chen†, G. D. Shi, G. Q. Li, X. Tang, X. N. Zhu, M. Z. Li, L. Yao, Y. J. Wei, W. Z. Song, Z. X. Sun, X. C. Fan, Z. X. Zhou, T. Qiu*, and Q. Hao*, “Plasmonic trimers designed as SERS-active chemical traps for subtyping of lung tumors”, Nature Communications, vol. 15, Article Number: 5855 (2024).  († Contributed Equally)  [Highlighted by 东大科研]  [Highlighted by HORIBA集团科学仪器事业部]



    Plasmonic materials can generate strong electromagnetic fields to boost the Raman scattering of surrounding molecules, known as surface-enhanced Raman scattering. However, these electromagnetic fields are heterogeneous, with only molecules located at the ‘hotspots’, which account for ≈ 1% of the surface area, experiencing efficient enhancement. Herein, we propose patterned plasmonic trimers, consisting of a pair of plasmonic dimers at the bilateral sides and a trap particle positioned in between, to address this challenge. The trimer configuration selectively directs probe molecules to the central traps where ‘hotspots’ are located through chemical affinity, ensuring a precise spatial overlap between the probes and the location of maximum field enhancement. We investigate the Raman enhancement of the Au@Al2O3-Au-Au@Al2O3 trimers, achieving a detection limit of 10-14 M of 4-methylbenzenethiol, 4-mercaptopyridine, and 4-aminothiophenol. Moreover, single-molecule SERS sensitivity is demonstrated by a bi-analyte method. Benefiting from this sensitivity, our approach is employed for the early detection of lung tumors using fresh tissues. Our findings suggest that this approach is sensitive to adenocarcinoma but not to squamous carcinoma or benign cases, offering insights into the differentiation between lung tumor subtypes.

  5. Q. Hao, Y. J. Chen, Y. J. Wei, G. Q. Li, X. Tang, D. X. Chen, X. N. Zhu, L. Yao, X. Zhao, M. Z. Li, J. W. Wang, X. C. Fan*, and T. Qiu, “Mechanism Switch in Surface-Enhanced Raman Scattering: The Role of Nanoparticle Dimensions”, The Journal of Physical Chemistry Letters, vol. 15, iss. 28, pp. 7183-7190 (2024).



    Surface-enhanced Raman scattering (SERS) is renowned for amplifying Raman signals, with electromagnetic mechanism (EM) enhancement arising from localized surface plasmon resonances and chemical mechanism (CM) enhancement as a result of charge transfer interactions. Despite the conventional emphasis on EM as a result of plasmonic effects, recent findings highlight the significance of CM when noble metals appear as smaller entities. However, the threshold size of the noble metal clusters/particles corresponding to the switch in SERS mechanisms is not clear at present. In this work, the VSe2-xOx/Au composites with different Au sizes are employed, in which a clear view of the SERS mechanism switch is observed at the Au size range of 16−21 nm. Our findings not only provide insight into the impact of noble metal size on SERS efficiency but also offer quantitative data to assist researchers in making informed judgments when analyzing SERS mechanisms.

  6. L. L. Lan, S. Yang, G. Q. Li, C. Y. Zhao, J. Liu, X. Tang, X. Zhao, Z. W. Qu, J. Gao, X. C. Fan*, and T. Qiu*, “Direct writing of flexible two-dimensional MXene arrays for ultrasensitive SERS sensing”, Journal of Materials Chemistry C, vol. 12, iss. 31, pp. 12115-12123 (2024).



    Two-dimensional (2D) MXene materials have emerged as promising candidates of surface-enhanced Raman scattering (SERS) to replace the conventional noble metal substrates. In this work, we develop a novel method to direct write flexible MXene substrates for the first time. The handwritten high-performance MXene SERS substrates, such as Ti2C, V2C, Mo2C, and Nb2C, are demonstrated, among which the Ti2C MXene shows the highest Raman enhancement factor of up to 4.7 × 105. The underlying SERS mechanisms of the handwritten Ti2C MXene substrates are primarily attributed to the efficient charge transfer at Ti2C/molecule interfaces, which is activated by the vibronic coupling of charge transfer resonance and molecular resonance. Furthermore, the handwritten MXene substrates realize sensitive detection of the prohibited fish drugs and selective detection of the target molecule in multicomponent environment, suggesting a great potential of MXene substrates in practical applications. This work not only provides a simple method to prepare high-performance SERS substrates, but opens up a new horizon for the applications of MXene in SERS sensing.

  7. L. L. Lan†, C. Y. Zhao†, X. Tang, J. Gao, G. Q. Li, H. Y. Cai, S. Yang, J. Liu, Z. W. Qu, X. C. Fan*, and T. Qiu*, “Charge-transfer-driven ultrasensitive SERS sensing in a two-dimensional titanium carbonitride MXene”, Optics Letters, vol. 49, iss. 9, pp. 2405-2408 (2024).  († Contributed Equally)



    Two-dimensional (2D) MXenes stand out as promising platforms for surface-enhanced Raman scattering (SERS) sensing owing to their metallic feature, various compositions, high surface area, compatibility with functionalization, and ease of fabrication. In this work, we report a high-performance 2D titanium carbonitride (Ti3CN) MXene SERS substrate. We reveal that the abundant electronic density of states near the Fermi level of Ti3CN MXene boosts the efficiency of photo-induced charge transfer at the interface of Ti3CN/molecule, resulting in significant Raman enhancement. The SERS sensitivity of Ti3CN MXene is further promoted through a 2D morphology regulation and molecular enrichment strategies. Moreover, prohibited drugs are detectable on this substrate, presenting the potential of trace-amount analysis on Ti3CN MXene. This work provides a deep insight of the SERS mechanisms of Ti3CN MXene and broadens the practical application of transition metal carbonitride MXene SERS substrates.

  8. X. Tang†, Q. Hao†, X. Y. Hou†, L. L. Lan, M. Z. Li, L. Yao, X. Zhao, Z. H. Ni*, X. C. Fan*, and T. Qiu*, “Exploring and Engineering 2D Transition Metal Dichalcogenides toward Ultimate SERS Performance”, Advanced Materials, vol. 36, iss. 19, Article Number: 2312348 (2024).  († Contributed Equally)  [Highlighted by js666金沙大厅登录入口]



    Surface-enhanced Raman spectroscopy (SERS) is an ultrasensitive surface analysis technique that is widely used in chemical sensing, bioanalysis, and environmental monitoring. The design of the SERS substrates is crucial for obtaining high-quality SERS signals. Recently, two-dimensional transition metal dichalcogenides (2D TMDs) have emerged as high-performance SERS substrates due to their superior stability, ease of fabrication, biocompatibility, controllable doping, and tunable bandgaps and excitons. In this review, we provide a systematic overview of the latest advancements in 2D TMDs SERS substrates. This review comprehensively summarizes the candidate 2D TMDs SERS materials, elucidates their working principles for SERS, explores the strategies to optimize their SERS performance, and highlights their practical applications. We particularly delve into the material engineering strategies, including defect engineering, alloy engineering, thickness engineering, and heterojunction engineering. Additionally, we discuss the challenges and future prospects associated with the development of 2D TMDs SERS substrates, outlining potential directions that may lead to significant breakthroughs in practical applications.

  9. Y. J. Wei, X. C. Fan, D. X. Chen, X. N. Zhu, L. Yao, X. Zhao, X. Tang, J. W. Wang, Y. J. Zhang, T. Qiu*, and Q. Hao*, “Probing Oxidation Mechanisms in Plasmonic Catalysis: Unraveling the Role of Reactive Oxygen Species”, Nano Letters, vol. 24, iss. 6, pp. 2110-2117 (2024).  [Highlighted by ACS材料X]  [Highlighted by 东大科研]



    Plasmon-induced oxidation has conventionally been attributed to the transfer of plasmonic hot holes. However, this theoretical framework encounters challenges in elucidating the latest experimental findings, such as enhanced catalytic efficiency under uncoupled irradiation conditions and superior oxidizability of silver nanoparticles. Herein, we employ liquid surface-enhanced Raman spectroscopy (SERS) as a real-time and in situ tool to explore the oxidation mechanisms in plasmonic catalysis, taking the decarboxylation of p-mercaptobenzoic acid (PMBA) as a case study. Our findings suggest that the plasmon-induced oxidation is driven by reactive oxygen species (ROS) rather than hot holes, holding true for both the Au and Ag nanoparticles. Subsequent investigations suggest that plasmon-induced ROS may arise from hot carriers or energy transfer mechanisms, exhibiting selectivity under different experimental conditions. The observations were substantiated by investigating the cleavage of the carbon–boron bonds. Furthermore, the underlying mechanisms were clarified by energy level theories, advancing our understanding of plasmonic catalysis.

  10. H. Huang†, S. Y. Wang†, X. C. Fan, D. Philo, L. P. Fang, W. G. Tu*, T. Qiu*, Z. G. Zou, and J. H. Ye*, “Near-Infrared Plasmon-Driven Nitrogen Photofixation Achieved by Assembling Size-Controllable Gold Nanoparticles on TiO2 Nanocavity Arrays”, ACS Sustainable Chemistry & Engineering, vol. 11, iss. 30, pp. 10993–11001 (2023).  († Contributed Equally)



    Solar-driven reduction of nitrogen (N2) to ammonia (NH3) offers an alternative carbon-free strategy toward cleaner and more sustainable NH3 production compared with the traditional Haber–Bosch process. However, the photofixation of N2 by low photonic-energy near-infrared (NIR) light still represents a huge challenge. Here, we design an Au/TiO2 hybrid plasmonic system via a solid-state dewetting process to arrange Au nanoparticles uniformly on ordered ultrathin TiO2 nanocavity arrays based on the anodic TiO2 templates, in which the tailored gold nanoparticle arrays serve as the mediator to guarantee NIR light harvesting and energy transfer. The oxidized layer of Ti is rich in oxygen vacancies produced simultaneously in solid-state-dewetting process which facilitates the adsorption and activation of N2 molecules. The charge transfer and N2 reduction reaction are driven in a tandem pathway, leading to an ammonia evaluation rate of 10.1 nmol cm-2 h-1 under NIR irradiation, while the photocatalytic performance shows no obvious decay after a cycle test. Briefly, the NIR-responsive Au/TiO2 plasmonic photocatalyst system opens a new insight to achieve a better utilization of solar energy for photocatalytic nitrogen fixation.

  11. X. Tang†, X. C. Fan†, J. Zhou†, S. Wang, M. Z. Li, X. Y. Hou, K. W. Jiang, Z. H. Ni, B. Zhao*, Q. Hao*, and T. Qiu*, “Alloy Engineering Allows On-Demand Design of Ultrasensitive Monolayer Semiconductor SERS Substrates”, Nano Letters, vol. 23, iss. 15, pp. 7037-7045 (2023).  († Contributed Equally)  [Highlighted by ACS材料X]  [Highlighted by ACS美国化学会]



    The chemical mechanism (CM) of surface-enhanced Raman scattering (SERS) has been recognized as a decent approach to mildly amplify Raman scattering. However, the insufficient charge transfer (CT) between the SERS substrate and molecules always results in unsatisfying Raman enhancement, exerting a substantial restriction for CM-based SERS. In principle, CT is dominated by the coupling between the energy levels of a semiconductor-molecule system and the laser wavelength, whereas precise tuning of the energy levels is intrinsically difficult. Herein, two-dimensional transition-metal dichalcogenide alloys, whose energy levels can be precisely and continuously tuned over a wide range by simply adjusting their compositions, are investigated. The alloys enable on-demand construction of the CT resonance channels to cater to the requirements of a specific target molecule in SERS. The SERS signals are highly reproducible, and a clear view of the SERS dependences on the energy levels is revealed for different CT resonance terms.

  12. L. Yao†, Q. Hao*†, M. Z. Li, X. C. Fan, G. Q. Li, X. Tang, Y. J. Wei, J. W. Wang, and T. Qiu, “Flexible plasmonic nanocavities: a universal platform for the identification of molecular orientations”, Nanoscale , vol. 15, iss. 14, pp. 6588-6595 (2023).  († Contributed Equally)



    The molecular orientation provides fundamental images to understand molecular behaviors in chemistry. Herein, we propose and demonstrate sandwich plasmonic nanocavities as a surface-selection ruler to illustrate the molecular orientations by surface-enhanced Raman spectroscopy (SERS). The field vector in the plasmonic nanocavity presents a transverse spinning feature under specific excitations, allowing the facile modulation of the field polarizations to selectively amplify the Raman modes of the target molecules. It does not require the knowledge of the Raman spectrum of a bare molecule as a standard and thus can be extended as a universal ruler for the identification of molecular orientations. We investigated the most widely used Raman probe, Rhodamine 6G (R6G) on the Au surface and tried to clarify the arguments about its orientations from our perspectives. The experimental results suggest concentration-dependent adsorption configurations of R6G: it adsorbs on Au primarily via an ethylamine group with the xanthene ring lying flatly on the metal surface at low concentrations, and the molecular orientation gradually changes from “flat” to “upright” with the increase of molecular concentrations.

  13. M. Z. Li†, Y. Zhou†, X. Tang, H. Zhang, S. L. Wang, A. M. Nie, X. C. Fan, Y. C. Cheng*, and T. Qiu*, “Monolayer Iron Oxychloride with a Resonant Band Structure for Ultrasensitive Molecular Sensing”, ACS Applied Materials & Interfaces , vol. 15, iss. 7, pp. 10166-10174 (2023).  († Contributed Equally)



    Two-dimensional layered materials (2DLMs) are expected to be next-generation commercial sensors for surface-enhanced Raman scattering (SERS) sensing owing to their unique structural features and physicochemical properties. The low sensitivity and poor universality of 2DLMs are the dominant barriers toward their practical applications. Herein, we report that monolayer iron oxychloride (FeOCl) with a naturally suitable band structure is a promising candidate for ultrasensitive SERS sensing. The generally boosted Raman scattering cross section of different analyte–FeOCl systems benefits from the resonant photoinduced charge transfer processes and strong ground-state interactions. In addition, the strong adsorption ability of monolayer FeOCl is crucial for rapid detection in practical applications, which is proven to be much better than those of conventional SERS sensors. Consequently, monolayer FeOCl enables diverse SERS applications, including multicomponent analysis, chemical reaction monitoring, and indirect ion sensing.

  14. X. C. Fan†, X. H. Zhang†, Y. Li, H. J. He, Q. X. Wang, L. L. Lan, W. Z. Song, T. Qiu*, and W. B. Lu*, “Flexible two-dimensional MXene-based antennas”, Nanoscale Horizons , vol. 8, pp. 309-319 (2023).  († Contributed Equally)



    With the growing development of the Internet of things, wearable electronic devices have been extensively applied in civilian and military fields. As an essential component of data transmission in wearable electronics, a flexible antenna is one of the key aspects of research. Conventional metal antennas suffer from a large skin depth, and cannot satisfy the requirements of wearable electronics such as light weight, flexibility, and thinness. Recently, a group of two-dimensional metallic metal carbides (named MXenes) have been explored as building blocks for high-performance flexible antennas with excellent flexibility and superior mechanical strength. The appearance of hydrophilic functional groups at the surface of a MXene allows simple, scalable, and environmentally friendly manufacturing of MXene-based antennas. In this minireview, some pioneering works of MXene-based flexible radio frequency components are summarized, and the existing bottlenecks and the future trends of this promising field are discussed.

  15. M. Z. Li†, Y. J. Wei†, X. C. Fan, G. Q. Li, X. Tang, W. Q. Xia, Q. Hao*, and T. Qiu*, “VSe2–xOx@Pd Sensor for Operando Self-Monitoring of Palladium-Catalyzed Reactions”, JACS Au , vol. 3, iss. 2, pp. 468-475 (2023).  († Contributed Equally)  [Highlighted by ACS美国化学会]



    Operando monitoring of catalytic reaction kinetics plays a key role in investigating the reaction pathways and revealing the reaction mechanisms. Surface-enhanced Raman scattering (SERS) has been demonstrated as an innovative tool in tracking molecular dynamics in heterogeneous reactions. However, the SERS performance of most catalytic metals is inadequate. In this work, we propose hybridized VSe2–xOx@Pd sensors to track the molecular dynamics in Pd-catalyzed reactions. Benefiting from metal–support interactions (MSI), the VSe2–xOx@Pd realizes strong charge transfer and enriched density of states near the Fermi level, thereby strongly intensifying the photoinduced charge transfer (PICT) to the adsorbed molecules and consequently enhancing the SERS signals. The excellent SERS performance of the VSe2–xOx@Pd offers the possibility for self-monitoring the Pd-catalyzed reaction. Taking the Suzuki–Miyaura coupling reaction as an example, operando investigations of Pd-catalyzed reactions were demonstrated on the VSe2–xOx@Pd, and the contributions from PICT resonance were illustrated by wavelength-dependent studies. Our work demonstrates the feasibility of improved SERS performance of catalytic metals by modulating the MSI and offers a valid means to investigate the mechanisms of Pd-catalyzed reactions based on VSe2–xOx@Pd sensors.

  16. L. L. Lan, X. C. Fan, C. Y. Zhao, J. Gao, Z. W. Qu, W. Z. Song, H. R. Yao, M. Z. Li, and T. Qiu*, “Two-dimensional MBenes with ordered metal vacancies for surface-enhanced Raman scattering”, Nanoscale , vol. 15, pp. 2779-2787 (2023).



    As an emerging class of two-dimensional (2D) materials, MBenes show enormous potential for optoelectronic applications. However, their use in molecular sensing as surface-enhanced Raman scattering (SERS)-active material is unknown. Herein, for the first time, we develop a brand-new high-performance MBene SERS platform. Ordered vacancy-triggered highly sensitive SERS platform with outstanding signal uniformity based on a 2D Mo4/3B2 MBene material was designed. The 2D Mo4/3B2 MBene presented superior SERS activity to most of the semiconductor SERS substrates, showing a remarkable Raman enhancement factor of 3.88 × 106 and an ultralow detection limit of 1 × 10−9 M. The underlying SERS mechanism is revealed from systematic experiments and density functional theory calculations that the ultrahigh SERS sensitivity of 2D Mo4/3B2 MBene is derived from the efficient photoinduced charge transfer process between MBene substrates and adsorbed molecules. The abundant electronic density of states near the Fermi level of 2D Mo4/3B2 MBene enables its Raman enhancement by a factor of 100 000 times higher than that of the bulk MoB. Consequently, the 2D Mo4/3B2 MBene could accurately detect various trace chemical analytes. Moreover, with ordered metal vacancies in the 2D Mo4/3B2 MBene, uniform charge transfer sites are formed, resulting in an outstanding signal uniformity with a relative standard deviation down to 6.0%. This work opens up a new horizon for the high-performance SERS platform based on MBene materials, which holds great promise in the field of chemical sensing.

  17. G. Q. Li†, Q. Hao*†, M. Z. Li, X. Zhao, W. Z. Song, X. C. Fan, and T. Qiu, “Quantitative SERS Analysis by Employing Janus Nanoparticles with Internal Standards”, Advanced Materials Interfaces , vol. 10, iss. 7, Article Number. 2202127 (2023).  († Contributed Equally)



    Surface-enhanced Raman scattering (SERS), a powerful analysis technique featuring ultrahigh sensitivity and the ability in chemically specific detection, has encountered intrinsic challenges in quantitative analysis due to the signal heterogeneity arising from sample preparation, molecular distribution, and experimental conditions. Herein, the plasmonic Janus nanoparticle, which is curved on one side and flat on the other, as a universal platform for quantitative analysis is proposed. The probe molecules are adsorbed on the curved side as internal standards to correct the signal fluctuation while the target molecules are adsorbed on the flat side for SERS measurement, and thus competitive adsorption between different molecules is prevented. Moreover, the Janus nanoparticles are partially embedded in a flexible and transparent membrane, enabling liquid-state SERS measurement which is favorable to form a uniform self-assembly molecular monolayer for quantitative SERS analysis. The quantitation of different biochemical molecules including Rhodamine 6G, crystal violet, and adenine are demonstrated, and an extension in linear response region for quantitative analysis is observed. The findings suggest a robust approach toward quantitative analysis.

  18. X. C. Fan, R. Wang, M. Z. Li, X. Tang, C. X. Xu*, Q. Hao, and T. Qiu*, “High-specificity molecular sensing on an individual whispering-gallery-mode cavity: coupling-enhanced Raman scattering by photoinduced charge transfer and cavity effects”, Nanoscale Horizons , vol. 8, pp. 195-201 (2023).  [Highlighted by Mat+]



    Optical whispering-gallery-mode (WGM) cavities have gained considerable interest because of their unique properties of enhanced light–matter interactions. Conventional WGM sensing is based on the mechanisms of mode shift, mode broadening, or mode splitting, which requires a small mode volume and an ultrahigh Q-factor. Besides, WGM sensing suffers from a lack of specificity in identifying substances, and additional chemical functionalization or incorporation of plasmonic materials is required for achieving good specificity. Herein, we propose a new sensing method based on an individual WGM cavity to achieve ultrasensitive and high-specificity molecular sensing, which combines the features of enhanced light–matter interactions on the WGM cavity and the “fingerprint spectrum” of surface-enhanced Raman scattering (SERS). This method identifies the substance by monitoring the Raman signal enhanced by the WGM cavity rather than monitoring the variation of the WGM itself. Therefore, ultrasensitive and high-specificity molecular sensing can be accomplished even on a low-Q cavity. The working principles of the proposed sensing method were also systematically investigated in terms of photoinduced charge transfer, Purcell effect, and optical resonance coupling. This work provides a new WGM sensing approach as well as a strategy for the design of a high-performance SERS substrate by creating an optical resonance mode.

  19. J. W. Wang*, Q. Hao*, H. Y. Dong, M. S. Zhu, L. Wu, L. X. Liu, W. X. Wang, O. G. Schmidt, and L. B. Ma, “Ultra-dense plasmonic nanogap arrays for reorientable molecular fluorescence enhancement and spectrum reshaping†”, Nanoscale, vol. 15, iss. 3, pp. 1128-1135 (2023).



    Understanding interactions between molecular transition and intense electromagnetic fields confined by plasmon nanostructures is of great significance due to their huge potential in fundamental cavity quantum electrodynamics and practical applications. Here, we report reorientable plasmon-enhanced fluorescence leveraging the flexibilities in densely-packed gold nanogap arrays by template-assisted depositions. By finely adjusting the symmetry of the unit structure, arrays of nanogaps along two nearly-orthogonal axes can be tailored collectively with spacing down to sub-10 nm on a single chip, facilitating distinct “inter-cell” and “intra-cell” plasmon couplings. Through engineering two sets of nanogaps, the varying hybridization-induced plasmonic bonding modes lead to adjustable splitting of the fluorescence emission peak with a width up to 81 nm and narrowing of linewidths up to a factor of 3. Besides, polarization anisotropy with a ratio up to 63% is obtained on the basis of spectrally separated local hotspots with discrepant oscillation directions. The developed plasmonic nanogap array is envisaged to provide a promising chip-scale, cost-effective platform for advancing fluorescence-based detection and emission technologies in both classical and quantum regimes.

  20. Y. J. Wei†, Q. Hao*†, X. C. Fan, M. Z. Li, L. Yao, G. Q. Li, X. Zhao, H. Huang, and T. Qiu, “Investigation of the Plasmon-Activated C–C Coupling Reactions by Liquid-State SERS Measurement”, ACS Applied Materials & Interfaces , vol. 14, iss. 48, pp. 54320–54327 (2022).  († Contributed Equally)  [Highlighted by ACS材料X]



    The implementation of plasmonic materials in heterogeneous catalysis was limited due to the lack of experimental access in managing the plasmonic hot carriers. Herein, we propose a liquid-state surface-enhanced Raman scattering (SERS) technique to manipulate and visualize heterogeneous photocatalysis with transparent plasmonic chips. The liquid-state measurement conquers the difficulties that arise from the plasmon-induced thermal effects, and thus the plasmon based strategies can be extended to investigate a wider range of catalytic reactions. We demonstrated the selection of reaction products by modulating the plasmonic hot carriers and explored the mechanisms in several typical C–C coupling reactions with 4-bromothiophenol (4-BTP) as reactants. The real-time experimental results suggest brand new mechanisms of the formation of C–C bonds on plasmonic metal nanoparticles (NPs): the residue of 4-BTP, but not thiophenol (TP), is responsible for the C–C coupling. Furthermore, this technique was extended to study the evolution of the Suzuki–Miyaura reaction on nonplasmonic palladium metals by establishing the charge transfer channels between palladium and Au NPs. The cleavage and formation of chemical bonds in each individual reaction step were discerned, and the corresponding working mechanisms were clarified.

  21. L. L. Lan†, X. C. Fan†, S. B. Yu, J. Gao, C. Y. Zhao, Q. Hao*, and T. Qiu*, “Flexible Two-Dimensional Vanadium Carbide MXene-Based Membranes with Ultra-Rapid Molecular Enrichment for Surface-Enhanced Raman Scattering”, ACS Applied Materials & Interfaces , vol. 14, iss. 35, pp. 40427-40436 (2022).  († Contributed Equally)   [Highlighted by 中国科学报]



    Two-dimensional (2D) MXene materials have attracted broad interest in surface-enhanced Raman scattering (SERS) applications by virtue of their abundant surface terminations and excellent photoelectric properties. Herein, we propose to design highly sensitive MXene-based SERS membranes by integrating a 2D downsizing strategy with molecular enrichment approaches. Two types of 2D vanadium carbide (V4C3 and V2C) MXenes are demonstrated for ultrasensitive SERS sensing, and corresponding SERS mechanisms including the effect of 2D vanadium carbide thickness on their electron density states and interfacial photoinduced charge transfer resonance were discussed. A 2D downsizing strategy authorizes nonplasmonic SERS detection with a sensitivity of 1 × 10-7 M. Moreover, the performance can be further upgraded by vacuum-assisted filtration, which enables an ultrarapid molecular enrichment (within 2 min), ultrahigh molecular removal rate (over 95%), and improved sensitivity (5 × 10-9 M). This work may shed light on the MXene-based materials as an innovative platform for nonplasmonic SERS detection.

  22. X. Tang†, X. C. Fan†, L. Yao, G. Q. Li, M. Z. Li, X. Zhao, Q. Hao*, and T. Qiu, “Electromagnetic Mechanisms or Chemical Mechanisms? Role of Interfacial Charge Transfer in the Plasmonic Metal/Semiconductor Heterojunction”, The Journal of Physical Chemistry Letters , vol. 13, iss. 33, pp. 7816-7823 (2022).  († Contributed Equally)  [Highlighted by ACS材料X]



    The plasmonic metal/semiconductor heterojunction provides a unique paradigm for manipulating light to improve the efficiency of plasmonic materials. Previous studies suggest that the improvement originates from the enhanced carrier exchanges between the plasmonic component of the heterojunction and molecules. This viewpoint, known as the chemical mechanism, is reasonable but insufficient, because the construction of the heterojunction will lead to a charge redistribution in the plasmonic component and cause changes in its physical characteristics. Herein, we will try to clarify that these changes are decisive factors in specific applications by investigating the surface-enhanced Raman scattering (SERS) behavior of a typical Ag/TiO2 heterojunction. We observed significant changes in SERS spectra by modulating the band alignment of the heterojunction in a loop. Identical trends in SERS spectra were observed despite the fact that the charge transfer from the heterojunction to molecules was blocked, suggesting that the major SERS enhancement originates from electromagnetic mechanisms rather than chemical ones.

  23. M. Z. Li†, T. B. Zhang†, L. Gao, Y. J. Wei, X. C. Fan, Y. H. He, X. H. Niu, J. L. Wang*, and T. Qiu*, “Monitoring substrate-induced electron–phonon coupling at interfaces of 2D organic/inorganic van der Waals heterostructures with in situ Raman spectroscopy”, Applied Physics Letters, vol. 120, iss. 18, Article Number: 181602 (2022). [Editor' s pick]   († Contributed Equally)  [Highlighted by AIP美国物理联合会]



    Multifunctional devices based on 2D organic/inorganic van der Waals heterostructures (2D OIHs) exhibit excellent properties due to extensive and flexible structural tunability. However, how to precisely regulate devices via in situ monitoring technique remains a great challenge, and corresponding development is still in its infancy. In this Letter, we show that Raman spectroscopy can serve as an effective in situ detection strategy to systematically observe the interfacial electron–phonon coupling (IEPC) between substrate and 2D OIHs. Combining non-adiabatic molecular dynamics simulations with ultrafast spectroscopy, we reveal that the different strengths of IEPC between substrates and 2D OIHs can directly modulate the photocarrier lifetimes of inorganic 2D materials, and therefore, indirectly modify the Raman-sensitive photo-induced charge transfer processes at the interface of 2D OIHs. Further in situ Raman evidence demonstrates the unique advantage of Raman spectroscopy with high sensitivity to monitor different substrate-induced IEPC under variable temperature.

  24. L. L. Lan, H. R. Yao, G. Q. Li, X. C. Fan, M. Z. Li, and T. Qiu*, “Structural engineering of transition-metal nitrides for surface-enhanced Raman scattering chips”, Nano Research, vol. 15, iss. 4, pp. 3794-3803 (2022).



    Noble-metal-free surface-enhanced Raman scattering (SERS) substrates have attracted great attention for their abundant sources, good signal uniformity, superior biocompatibility, and high chemical stability. However, the lack of controllable synthesis and fabrication of noble-metal-free substrates with high SERS activity impedes their practical applications. Herein, we propose a general strategy to fabricate a series of planar transition-metal nitride (TMN) SERS chips via an ambient temperature sputtering deposition route. For the first time, tungsten nitride (WN) and tantalum nitride (TaN) are used as SERS materials. These planar TMN chips show remarkable Raman enhancement factors (EFs) with ∼ 105 owing to efficient photoinduced charge transfer process between TMN chips and probe molecules. Further, structural engineering of these TMN chips is used to improve their SERS activity. Benefiting from the synergistic effect of charge transfer process and electric field enhancement by constructing a nanocavity structure, the Raman EF of WN nanocavity chips could be greatly improved to ∼ 1.29 × 107, which is an order of magnitude higher than that of planar chips. Moreover, we also design the WN/monolayer MoS2 heterostructure chips. With the increase of surface electron density on the upper WN and more exciton resonance transitions in the heterostructure, a ∼ 1.94 × 107 level EF and a 5 × 10-10 M level detection limit could be achieved. Our results provide important guidance for the structural design of ultrasensitive noble-metal-free SERS chips.

  25. Q. Hao, Z. H. Peng, J. W. Wang, X. C. Fan, G. Q. Li, X. Zhao, L. B. Ma, T. Qiu*, and O. G. Schmidt, “Verification and Analysis of Single-Molecule SERS Events via Polarization-Selective Raman Measurement”, Analytical Chemistry, vol. 94, iss. 2, pp. 1046-1051 (2022).



    We propose polarization-selective Raman measurement as a decent method for single-molecule surface-enhanced Raman scattering (SMSERS) verification. This approach features rapid acquisition of SMSERS events and appeals liberal requirements for analyte concentration. It is demonstrated as an efficient tool in sorting out dozens of SMSERS events from a large-scale plasmonic dimer array. In addition, it allows identification of a mixed SMSERS event containing two different individual molecules. In this article, the RPM method is employed to explore the underlying mechanisms of signal blinking, spectral wandering, and other unique characteristics in SMSERS. We observed synchronized blinking of different modes from one Rhodamine 6G (R6G) molecule, but a disagreement is found in a mixed SMSERS event containing one R6G molecule and one crystal violet molecule. Our approach offers a reliable means to interpret SMSERS events in statistical terms and facilitate the fundamental understanding of SMSERS.

  26. M. Z. Li†, Y. J. Wei†, X. C. Fan, G. Q. Li, Q. Hao, and T. Qiu*, “Mixed-dimensional van der Waals heterojunction-enhanced Raman scattering”, Nano Research, vol. 15, iss. 1, pp. 637-643 (2022).   († Contributed Equally)



    Van der Waals heterojunctions (vdWHs) provide an excellent material system for the research of heterojunction-enhanced Raman scattering (HERS) due to their complexity and diversity. However, the traditional two-dimensional vdWHs are not conducive to the full utilization of near-field light due to the limitation of single dimension. Herein, we fabricate T-shaped mixed-dimensional SnSe2/ReS2 vdWHs via chemical vapor deposition and wetting transfer method, and demonstrate that the mixed-dimensional vdWHs can be used as ultrasensitive HERS chips based on the effective photo-induced charge transfer. Besides, the radiative energy transfer effect enhanced by near-field light further magnifies the HERS signals, improving the detection limit of rhodamine 6G (R6G) to femtomolar level. Furthermore, we demonstrate that the ultrasensitive screening of crystal violet in multicomponent solutions adsorbed on SnSe2/ReS2 vdWHs can be achieved by adjusting the laser wavelength, which has not been achieved by noble metal materials. This work provides new insights into the mixed-dimensional vdWHs and demonstrates the great application potential of T-shaped heterojunctions.

  27. X. C. Fan†, P. H. Wei†, G. Q. Li, M. Z. Li, L. L. Lan, Q. Hao*, and T. Qiu*, “Manipulating Hot-Electron Injection in Metal Oxide Heterojunction Array for Ultrasensitive Surface-Enhanced Raman Scattering”, ACS Applied Materials & Interfaces, vol. 13, iss. 43, pp. 51618-51627 (2021).   († Contributed Equally)



    Efficient photoinduced charge transfer (PICT) resonance is crucial to the surface-enhanced Raman scattering (SERS) performance of metal oxide substrates. Herein, we venture into the hot-electron injection strategy to achieve unprecedented enhanced PICT efficiency between substrates and molecules. A heterojunction array composed of plasmonic MoO2 and semiconducting WO3–x is designed to prove the concept. The plasmonic MoO2 generates intense localized surface plasmon resonance under illumination, which can generate near-field Raman enhancement as well as accompanied plasmon-induced hot-electrons. The hot-electron injection in direct interfacial charge transfer and plasmon-induced charge transfer process can effectively promote the PICT efficiency between substrates and molecules, achieving a record Raman enhancement factor among metal oxide substrates (2.12 × 108) and the ultrasensitive detection of target molecule down to 10-11 M. This work demonstrates the possibility of hot-electron manipulation to realize unprecedented Raman enhancement in metal oxides, offering a cutting-edge strategy to design high-performance SERS substrates.

  28. X. Gao†, X. C. Fan†, and J. Y. Zhang*, “Tunable Plasmonic Gallium Nano Liquid Metal from Facile and Controllable Synthesis”, Materials Horizons, vol. 8, pp. 3315-3323 (2021).   [Inside Back Cover]  [Highlighted by RSC Publishing]  († Contributed Equally)



    Liquid metal (LM), gallium (Ga), is famous for its metallic properties with unique fluidity and has been extensively utilized in modern technologies. However, chemical strategies towards nanostructured Ga are extremely challenging, which severely limits further advanced applications of Ga. This work reports a facile method, the classical galvanic replacement reaction (GRR), to readily realize the synthesis of uniform Ga nano LM through sacrificial seeds (zinc) and gallium ions (Ga3+). Different from previously tedious Ga nanoparticles synthesis, the GRR can be achieved under mild conditions without involving any highly active reagents and special equipment. Surprisingly, the temperature heavily influences the results of GRR due to the unique solid-liquid phase transition of Ga LM. This work figures out the critical issues of temperature, oxygen and solvent in the GRR to successfully prepare Ga nanodroplets. Interestingly, the GRR provides a convenient strategy to control the size of Ga nano LM to mediate the localized surface plasmon resonance (LSPR) in the ultraviolet region, which is hardly observed in noble metals. Besides, the nano Ga from GRR exhibits remarkable SERS detection capability with extremely low limit of detection (10-6 M), which ranks the highest enhancement factor with average value exceeding 105 among Ga material. Moreover, the SERS activity of the nano Ga shows no obvious decrease within 60 days, verifying its excellent storage stability. This work demonstrates a facile chemistry for Ga LM, which could greatly benefit its potential applications in the future.

  29. 司丽芳, 范兴策*, 侯翔宇, 李国群, 龙开琳, 罗小光, 倪振华, 邱腾, “氧化铟锡纳米阵列中的协同增强拉曼散射现象研究”, 光散射学报, vol. 33, no. 1, pp. 32 - 39 (2021).


    一些具有表面增强拉曼散射（Surface-enhanced Raman Scattering, SERS）性能的金属氧化物材料近年来被广泛研究，它们具有相较于传统贵金属材料更为优异的信号均匀度、材料稳定性和生物兼容性等。目前金属氧化物SERS的研究瓶颈在于拉曼增强效果一般，需要对其检测灵敏度进行有效提升方可实现日后的广泛应用。因为金属氧化物具有若干种区别于贵金属的材料特征，例如带隙、化学计量比、激子等多个维度的材料特性，所以金属氧化物可以通过调控若干种材料性能以达到协同增强拉曼散射的目的。本文选取氧化铟锡（Indium Tin Oxide, ITO）作为示例来研究重掺杂金属氧化物纳米阵列中的协同增强拉曼散射现象。该体系同时集成了重掺杂半导体材料的SERS性能以及光学干涉腔的特征，协同性地实现了ITO纳米阵列的SERS性能提升。该研究为金属氧化物SERS基底的研究提供了一个很好的案例，在对金属氧化物SERS材料性能进行提升时，需要对金属氧化物中可能产生的干涉现象进行有效利用。

  30. L. Tao*, Z. Y. Li, K. Chen*, Y. Q. Zhou, H. Li, X. M. Wang, R. Z. Zhan, X. Y. Hou, Y. Zhao, J. L. Xu, T. Qiu, X. Wan, and J. -B. Xu*, “A spontaneously formed plasmonic-MoTe2 hybrid platform for ultrasensitive Raman enhancement”, Cell Reports Physical Science, vol. 2, iss. 8, Article Number: 100526 (2021).


  31. X. Y. Hou, X. Tang, Y. J. Wei, S. S. Wang, Q. Hao, J. -M. Hou, and T. Qiu*, “Role of dispersion relation effect in topological surface-enhanced Raman scattering”, Cell Reports Physical Science, vol. 2, iss. 7, Article Number: 100488 (2021).



    Topological surface-enhanced Raman scattering (T-SERS) is a phenomenon in which topological materials change the density of states (DOS) of the substrate through linear dispersion relation to boost photoinduced charge transfer and enhance Raman scattering. Through theoretical and experimental research, we show that the dispersion relation effect in topological materials is the main reason for T-SERS. In theory, the dispersion relation and dimension of the band structure will affect the distribution of DOS near the Fermi surface of substrates, and the change of DOS will lead to the different contribution of charge transfer for SERS. In experiments, the enhancement effect of topological insulators (Bi2Se3, Sb2Te3) and topological semimetal (PtSe2) on the Raman scattering of various molecules are compared. Among these materials, PtSe2 can achieve Raman enhancement of R6G molecules with the concentration of 10-9 M.

  32. R. Wang, C. X. Xu*, D. T. You, X. X. Wang, J. P. Chen, Z. L. Shi, Q. N. Cui, and T. Qiu*, “Ultra-Strong Mode Confinement at Semishell Metal/insulator/semiconductor Interface for Nanolaser”, Journal of Luminescence, vol. 238, Article Number: 118242 (2021).



    Metal/insulator/semiconductor structure, as a typical interface in conventional electrical and optoelectronic devices, can also act as a plasmon-exciton coupling configuration for designing new concept nanophotonic devices, such as plasmon nanolaser, which is promising to play a coherent light source for nanophotonic integration owing to the spatial localization of surface plasmon (SP). Therefore, it is very important to construct a proper configuration and optimize the nanophotonic performance. In this paper, we designed the Al-semishell structure on ZnO nanorod with SiO2 insulator layer, and further realized plasmonic lasing with high performance. The simulation demonstrated a small effective mode area and high effective index of the semishell ZnO nanocavity with a thickness-optimized dielectric layer, while the experiment revealed plasmon lasing with low threshold (27 MW/cm2) and high quality factor (Q = 485), due to the ultra-strong optical confinement. What's more, the plasmon-exciton coupling mechanism of the plasmonic lasing was further investigated through systematically analyzing about lasing mode shift, as well as temperature-dependent and time-resolved photoluminescence (PL). Quite different from electron-hole plasma (EHP) effect in photonic nanolaser from bare ZnO, the weak dependence of temperature on the PL decay life in semishell ZnO plasmonic nanolaser also reveals the coupling of SP-exciton which accelerates the temporal response under direct laser modulation. The presented results create the possibility of highly integrated coherent light sources operating at extremely high speeds.

  33. X. Z. Lang*, X. D. Wang, J. Ma, and T. Qiu, “Flexible fabrication of new-type porous anodic alumina membranes with tunable geometric features by low-cost nanoimprint lithography”, Nanoscale Advances, vol. 3, iss. 10, pp. 2918-2923 (2021).



    A novel process for the flexible fabrication of new-type porous anodic alumina (PAA) membranes with tunable geometric features is described. In this process, the conventional PAA template as a cost-effective nanoimprint stamp is employed to transfer the anti-structure nanopits onto aluminum sheet substrates, and the subsequent guided anodization of the pre-patterned substrates leads to new-type PAAs. By further adjusting the anode voltages of PAA stamps, imprinting pressures and guided anode voltages, a series of new-type PAAs with controlled para-pore spacing, surface topography and nanopore arrangement are achieved. The new-type PAAs provide a low-cost flexible option for the preparation of arrays with utility in photonic, electronic and magnetic devices.

  34. R. Wang, C. X. Xu*, D. T. You, X. X. Wang, J. P. Chen, Z. L. Shi, Q. N. Cui, and T. Qiu*, “Plasmon–exciton coupling dynamics and plasmonic lasing in a core–shell nanocavity”, Nanoscale, vol. 13, iss. 14, pp. 6780-6785 (2021). [Front Cover]



    Plasmonic nanolasers based on the spatial localization of surface plasmons (SPs) have attracted considerable interest in nanophotonics, particularly in the desired application of optoelectronic and photonic integration, even breaking the diffraction limit. Effectively confining the mode field is still a basic, critical and challenging approach to improve optical gain and reduce loss for achieving high performance of a nanolaser. Here, we designed and fabricated a semiconductor/metal (ZnO/Al) core–shell nanocavity without an insulator spacer by simple magnetron sputtering. Both theoretical and experimental investigations presented plasmonic lasing behavior and SP-exciton coupling dynamics. The simulation demonstrated the three-dimensional optical confinement of the light field in the core–shell nanocavity, while the experiments revealed a lower threshold of the optimized ZnO/Al core–shell nanolaser than the same-sized ZnO photonic nanolaser. More importantly, the blue shift of the lasing mode demonstrated the SP-exciton coupling in the ZnO/Al core–shell nanolaser, which was also confirmed by low-temperature photoluminescence (PL) spectra. The analysis of the Purcell factor and PL decay time revealed that SP-exciton coupling accelerated the exciton recombination rate and enhanced the conversion of spontaneous radiation into stimulated radiation. The results indicate an approach to design a real nanolaser for promising applications.

  35. L. L. Lan, Y. M. Gao, X. C. Fan, M. Z. Li, Q. Hao, and T. Qiu*, “The origin of ultrasensitive SERS sensing beyond plasmonics”, Frontiers of Physics, vol. 16, iss. 4, Article Number: 43300 (2021). [Invited Review] [Cover illustration]



    Plasmon-free surface-enhanced Raman scattering (SERS) substrates have attracted tremendous attention for their abundant sources, excellent chemical stability, superior biocompatibility, good signal uniformity, and unique selectivity to target molecules. Recently, researchers have made great progress in fabricating novel plasmon-free SERS substrates and exploring new enhancement strategies to improve their sensitivity. This review summarizes the recent developments of plasmon-free SERS substrates and specially focuses on the enhancement mechanisms and strategies. Furthermore, the promising applications of plasmon-free SERS substrates in biomedical diagnosis, metal ions and organic pollutants sensing, chemical and biochemical reactions monitoring, and photoelectric characterization are introduced. Finally, current challenges and future research opportunities in plasmon-free SERS substrates are briefly discussed.

  36. 赵星, 郝祺*, 倪振华, 邱腾, “单分子表面增强拉曼散射的光谱特性及分析方法”, 物理学报, vol. 70, no. 13, Article Number: 137401 (2021).   [编辑推荐]


    单分子检测代表分子检测灵敏度的极限，能够提供传统检测方式无法提供的物理信息，在化学分析、 分子动力学机理、蛋白质解析等领域具有广阔的应用前景，具有重要的科学研究价值。具体而言，单分子 检测能对复杂体系中的分子进行识别和计数，给出分子的分布信息；也可以对单个分子在吸附、反应等过 程中的实时衍变进行追踪，研究分子动力学的内在机制。单分子表面增强拉曼散射是单分子检测领域最近 兴起的一门新方法，其特色在于具有特异性分子识别能力，可以提供分子成键变化等动态信息。这种方法 适用于研究分子的演化过程、分子与环境的电荷相互作用，从而揭示分子的反应途径、分布状态、吸附方 式、电荷交换等重要信息。单分子表面增强拉曼散射的概念提出较早，但是缺乏高效的采集方法和精确的 判定依据，本文将对采集方法的优化进行梳理分析，从非统计学和统计学两个角度对其进行讨论，并重点 对双分子分析检测法做详细介绍。另一方面，由于单分子表面增强拉曼散射研究涉及各种交叉学科、内涵 广泛，相关研究需要对光谱背后的相关机制有着深刻的理解和认识。为此，本文基于当前的相关研究工作， 从分子漂移、光谱闪烁以及展宽等特有现象入手，分析了单分子表面增强拉曼散射的波动特征及其对应的 物理机制，并对其应用前景做了简要探讨。

  37. Y. M. Yang*, F. Kong, J. Y. Fan, X. C. Fan, M. Z. Li, and T. Qiu*, “Stability of the structure and redox state of ferricytochrome c in the desolvation process”, Vibrational Spectroscopy, vol. 113, Article Number: 103220 (2021).



    Stability of the structure and redox state of ferricytochrome c during continuous changing of the hydration environment from dilute solution to condensed phase was studied based on real-time resonance Raman measurement. Our experimental results indicated that the structure and redox state of ferricytochrome c were sufficiently maintained during the entire desolvation process, which reflected that the stabilizing excluded-volume effect was stronger than the destabilizing crowder-protein interaction, at the case of globular mini-protein itself acting as the crowder. Rapid reduction of ferricytochrome c was observed at measurement sites at the time of solution to condensed phase transition. Similar phenomenon was observed on cytochrome c adsorbed on indium tin oxide surface. At present conditions, the rapid reduction was found to be derived mainly from thermal reduction under laser illumination and secondarily from photoreduction induced by the residual adsorbed ferrocyanide anions. After re-dissolved, the protein which had undergone sufficient desolvation recovered the structure and redox state in the initial solution phase, suggesting that the crowding effect in solution prevented large protein deformations observed in gas phase condition.

  38. 侯翔宇, 邱腾*, “低维光电材料缺陷与界面增强拉曼散射”, 中国光学, vol. 14, no. 1, pp. 170-181 (2021). [Invited Review]


    近年来，一系列新型低维光电材料相继涌现，展现出优异的性能。这些光电材料与表面增强拉曼散射(SERS)技术相结合，显示出巨大的应用潜力，有望成为高灵敏SERS活性基底。缺陷与界面调控是低维光电材料SERS应用的重要策略，本文将重点介绍新型低维光电材料缺陷与界面增强拉曼散射的种类和增强机理。通过对缺陷与界面增强拉曼散射的应用和研究前景的展望，启发人们对SERS研究的再思考和再认识。

  39. M. Z. Li, Y. M. Gao, X. C. Fan, Y. J. Wei, Q. Hao, and T. Qiu*, “Origin of layer-dependent SERS tunability in 2D transition metal dichalcogenides”, Nanoscale Horizons, vol. 6, iss. 2, pp. 186-191 (2021).   [Highlighted by HORIBA]  [Featured in Themed Collection: Nanoscale Horizons Most Popular 2021 Articles]



    Two-dimensional (2D) semiconductors are expected to replace noble metals to become the matrix materials of the next generation of commercial surface-enhanced Raman scattering (SERS) chips. Herein, we systematically studied the influence of the interlayer interaction on the SERS activity of 2D semiconductors from a brand-new perspective and comprehensively analyzed the physicochemical process of 2D semiconductor interlayer modulated SERS. Taking transition metal dichalcogenides as examples, we chose PtSe2 with strong interlayer interactions and ReS2 with weak interlayer interactions to analyze the physicochemical process of 2D semiconductor interlayer modulated SERS by first-principles calculations. PtSe2 and ReS2 samples with various thicknesses were prepared respectively, and the results of comparative experiments proved that the layer-dependent SERS tunability of 2D semiconductors is directly related to the interlayer interaction. This work provided a novel method for further improving the SERS detection limit of 2D semiconductors and a possible strategy for the industrial upgrading of commercial SERS chips.

  40. Q. Hao†, M. Z. Li†, J. W. Wang, X. C. Fan, J. Jiang, X. X. Wang, M. S. Zhu, T. Qiu*, L. B. Ma, P. K. Chu, and O. G. Schmidt, “Flexible Surface-Enhanced Raman Scattering Chip: A Universal Platform for Real-Time Interfacial Molecular Analysis with Femtomolar Sensitivity”, ACS Applied Materials & Interfaces , vol. 14, iss. 48, pp. 54174-54180 (2020).   († Contributed Equally)



    We propose and demonstrate a flexible surface-enhanced Raman scattering (SERS) chip as a versatile platform for femtomolar detection and real-time interfacial molecule analysis. The flexible SERS chip is composed of a flexible and transparent membrane and embedded plasmonic dimers with ultrahigh particle density and ultrasmall dimer gap. The chip enables rapid identification for residuals on solid substrates with irregular surfaces or dissolved analytes in aqueous solution. The sensitivity for liquid-state measurement is down to 0.06 molecule per dimers for 10–14 mol·L–1 Rhodamine 6G molecule without molecule enrichment. Strong signal fluctuation and blinking are observed at this concentration, indicating that the detection limit is close to the single-molecule level. Meanwhile, the homogeneous liquid environment facilities accurate SERS quantification of analytes with a wide dynamic range. The synergy of flexibility and liquid-state measurement opens up avenues for the real-time study of chemical reactions. The reduction from p-nitrothiophenol (PNTP) to p-aminothiophenol (PATP) in the absence of the chemical reducing agents is observed at liquid interfaces by in situ SERS measurements, and the plasmon-induced hot electron is demonstrated to drive the catalytic reaction. We believe this robust and feasible approach is promising in extending the SERS technique as a general method for identifying interfacial molecular traces, tracking the evolution of heterogeneous reactions, elucidating the reaction mechanisms, and evaluating the environmental effects such as pH value and salty ions in SERS.

  41. L. L. Lan, X. C. Fan, Y. M. Gao, G. Q Li, Q. Hao, and T. Qiu*, “Plasmonic metal carbide SERS chips”, Journal of Materials Chemistry C , vol. 8, iss. 41, pp. 14523-14530 (2020).



    With the intrinsic drawbacks of high processing costs, expensive raw materials and poor product-stability, the practical applications of commercial noble metal surface-enhanced Raman scattering (SERS) chips have been severely impeded. Thus, it comes as a significant challenge to develop an uncomplicated preparation method and search for low-cost candidates for highly-sensitive commercial SERS chips. Herein, we come up with a facile and universal approach to fabricate a series of plasmonic metal carbide SERS chips. This is the first time that tungsten carbide, molybdenum carbide, and niobium carbide are reported as SERS materials with cheap prices. Furthermore, we prove that the high SERS activity of these materials comes from strong localized surface plasmon resonance effects. These metal carbide chips could realize the detection of diverse organic molecules, and the detection limit concentration of rhodamine 6G was found to be below 10-8 M, which is even lower than some of the noble metal SERS substrates. Our work provides an efficient strategy to upgrade the industries of commercial SERS chips.

  42. X. Y. Hou, Q. Lin, Y. J. Wei, Q. Hao, Z. H. Ni*, and T. Qiu*, “Surface-Enhanced Raman Scattering Monitoring of Oxidation States in Defect-Engineered Two-Dimensional Transition Metal Dichalcogenides”, The Journal of Physical Chemistry Letters , vol. 11, iss. 19, pp. 7981-7987 (2020).



    Recent studies have found that some transition metal dichalcogenides (TMDs)with their own defects are difficult to store in the air for a long time. Worse stability of TMDsunder extreme conditions has also been reported. Therefore, monitoring the oxidation anddegradation processes of TMDs can directly guide the stability prediction of TMD-baseddevices and monitor TMDs quality. Herein, with the case of molybdenum disulfide, UV−ozone defect engineering is used to simulate the oxidation and degradation of TMDs undersevere conditions. Surface-enhanced Raman scattering based on a chemical mechanism wasfirst introduced to the dynamic monitoring of defect evolution in the oxidation anddegradation of TMDs, and succeeds in tracking the TMDs oxidation state by the quantitativemethod. It is expected that this technology can be extended to the quantification and trackingof oxidation and degradation of other 2D materials.

  43. X. C. Fan, Q. Hao, M. Z. Li, X. Y. Zhang, X. Z. Yang, Y. F. Mei, and T. Qiu*, “Hotspots on the Move: Active Molecular Enrichment by Hierarchically Structured Micromotors for Ultrasensitive SERS Sensing”, ACS Applied Materials & Interfaces , vol. 12, pp. 28783–28791 (2020).   [Highlighted by Chemical & Engineering News: "Chemistry in Pictures: The swimmers who do SERS"] 



    Surface-enhanced Raman scattering (SERS) is recognized as one of the most sensitive spectroscopic tools for chemical and biological detections. Hotspots engineering has expedited promotion of SERS performance over the past few decades. Recently, molecular enrichment has proven to be another effective approach to improve the SERS performance. In this work, we propose a concept of “motile hotspots” to realize ultrasensitive SERS sensing by combining hotspots engineering and active molecular enrichment. High-density plasmonic nanostructure-supporting hotspots are assembled on the tubular outer wall of micromotors via nanoimprint and rolling origami techniques. The dense hotspots carried on these hierarchically structured micromotors (HSMs) can be magnet-powered to actively enrich molecules in fluid. The active enrichment manner of HSMs is revealed to be effective in accelerating the process of molecular adsorption. Consequently, SERS intensity increases significantly because of more molecules being adjacent to the hotspots after active molecular enrichment. This “motile hotspots” concept provides a synergistical approach in constructing a SERS platform with high performance. Moreover, the newly developed construction method of HSMs manifests the possibility of tailoring tubular length and diameter as well as surface patterns on the outer wall of HSMs, demonstrating good flexibility in constructing customized micromotors for various applications.

  44. H. Huang, X. S. Wang, D. Philo, F. Ichihara, H. Song, Y. X. Li, D. Li, T. Qiu*, S. Y. Wang*, and J. H. Ye*, “Toward visible-light-assisted photocatalytic nitrogen fixation: A titanium metal organic framework with functionalized ligands”, Applied Catalysis B: Environmental , vol. 267, Article Number: 118686 (2020).  [Highly Cited Paper]



    The fixation of atmospheric dinitrogen to ammonia is one of the most essential processes for sustaining life. Since the N≡N bond in dinitrogen is one of the strongest bonds in chemistry, it remains a grand challenge to develop efficient catalysts for fixation of N2 under ambient conditions. Herein we report for the first time on visible-light-assisted photocatalytic nitrogen fixation by metal organic framework material at room temperature and pressure. The Ti3+ species induced by electron transfer from ligand-to-metal charge transfer process provide active sites for N2 reduction. Furthermore, visible-light-assisted photocatalytic N2 fixation is achieved by ligands functionalization which extend the light harvesting of the MOF to visible region. The integration of Ti sites and amine-functionalized linkers in NH2-MIL-125 (Ti) shows the highest visible light photocatalysis efficiency at a rate of 12.3 μmol g−1 h−1. This Ti MOF system therefore shows a potential as a new design of combining light-harvesting and catalytic components in a single solid platform for green NH3 production.

  45. X. Y. Hou, X. Y. Zhang, Q. W. Ma, X. Tang, Q. Hao, Y. C. Cheng*, and T. Qiu*, “Alloy Engineering in Few‐Layer Manganese Phosphorus Trichalcogenides for Surface‐Enhanced Raman Scattering”, Advanced Functional Materials , vol. 30, iss. 12, Article Number: 1910171 (2020).



    Manganese phosphorus trichalcogenides are widely used in the field of photocatalysis and magnetic studies due to their broadband gaps. Herein, an alloy engineering method for the few‐layer manganese phosphorus trichalcogenides (MnPS3–xSex, 0 ≤ x ≤ 3) in surface‐enhanced Raman scattering (SERS) is reported. A new strategy, with the coupling of exciton resonance (µex) and photoinduced charge transfer (PICT), is applied to screen out materials for SERS enhancement. According to the calculation of density functional theory, the bandgap of manganese phosphorus trichalcogenides (MnPS3) can be adjusted to match the band energy of Rhodamine 6G molecules by alloy engineering. Furthermore, a series of few‐layer MnPS3–xSex (0 ≤ x ≤ 3) are fabricated to study the PICT‐induced SERS behavior under resonance excitation. The good performance with a detection limit down to 10−9 m indicates that the synergistic resonances between µex and PICT are crucial to the enhancement.

  46. X. C. Fan, Q. Hao*, T. Qiu, and Paul K. Chu*, “Improving the performance of light-emitting diodes via plasmonic-based strategies”, Journal of Applied Physics , vol. 127, iss. 4, Article Number: 040901 (2020). [Invited Review] [Editor' s Pick]



    Light-emitting diodes (LEDs), featuring long lifetime, small size, and low energy consumption, are increasingly popular for displays and general light sources. In the past decades, new light-emitting materials and novel device configurations are being continuously investigated to obtain highly efficient LEDs. Nevertheless, the unsatisfying external quantum efficiency severely limits their commercial implementation. Among all the approaches to boost the efficiency of LEDs, the incorporation of plasmonic structures exhibits great potential in increasing the spontaneous emission rates of emitters and improving the light extraction efficiency. In this Perspective, the methods to deal with challenges in quantum-well-based LEDs and organic LEDs by employing plasmonic materials are described, the mechanisms of plasmonic-based strategies to improve the light generation and extraction efficiency are discussed, and the plasmonic control over directional emission of phosphors is introduced as well. Moreover, important issues pertaining to the design, fabrication, and manipulation of plasmonic structures in LEDs to optimize the device performance, as well as the selection roles in finding appropriate plasmonic materials and structures for desired LED devices, are explained. This perspective lists the challenges and opportunities of plasmonic LEDs, with the aim of providing some insights into the future trends of plasmonic LEDs.

  47. L. L. Lan, X. Y. Hou, Y. M. Gao, X. C. Fan, and T. Qiu*, “Inkjet-printed paper-based semiconducting substrates for surface-enhanced Raman spectroscopy”, Nanotechnology , vol. 31, iss. 5, Article Number: 055502 (2020).



    As a powerful analytical tool of molecular detection, surface-enhanced Raman spectroscopy (SERS) has attracted great attention in varied fields. However, it has seriously impeded the development of SERS that the preparation process is generally complicated and traditional substrates lack eco-friendliness, economy and flexibility. Herein, we fabricated the inkjet-printed paper-based semiconducting SERS substrates for the first time via an inexpensive office inkjet printer with representative two-dimensional MoO3−x nanosheets ink. Compared with conventional substrates, these paper-based semiconducting substrates not only could meet the requirements of simple and large-scale preparation, but also realize efficient sample collection by merely swabbing the surface. We obtained the detection limit concentration of rhodamine 6G as low as 10–7 M. Furthermore, these flexible paper-based substrates were successfully applied to detect crystal violet and malachite green on the fish surface by swabbing. With immense potentiality in practical applications, the inkjet-printed paper-based semiconducting SERS substrates are expected to open a new prospect for SERS.

  48. X. Y. Hou, X. C. Fan, P. H. Wei, and T. Qiu*, “Planar transition metal oxides SERS chips: a general strategy”, Journal of Materials Chemistry C , vol. 7, iss. 36, pp. 11134-11141 (2019).



    Noble metal surface-enhanced Raman scattering (SERS) chips based on plasmonic nanostructures have been commercialized. However, replacing the complex and high-cost preparation method remains a challenge. In this case, the expansion of noble metal-comparable SERS materials for commercial chip applications is a fundamental issue. Non-metals fabricated using the chemical method have achieved SERS activity comparable to that of noble metals, but it is hard to obtain planar materials using this technique and therefore non-metal chips have not yet been developed. Herein, we systematically studied the possibility that transition metal oxides (TMOs) could rival noble metals for SERS activity. Nonstoichiometric group-IVB, VB and VIB TMOs materials were fabricated using a general strategy based on magnetron sputtering with a H2 annealing treatment. The limit of detection was below 10−9 M owing to the process of photoinduced charge transfer (PICT). For the first time, we obtained commercially viable non-metal SERS chips using a convenient and cheap physical method. A theoretical explanation of PICT proves that this technique can be used to achieve more SERS chips.

  49. X. C. Fan, M. Z. Li, Q. Hao, M. S. Zhu, X. Y. Hou, H. Huang, L. B. Ma, O. G. Schmidt, and T. Qiu*, “High SERS Sensitivity Enabled by Synergistically Enhanced Photoinduced Charge Transfer in Amorphous Nonstoichiometric Semiconducting Films”, Advanced Materials Interfaces , vol. 6, iss. 19, Article Number: 1901133 (2019).



    Semiconducting surface‐enhanced Raman scattering (SERS) materials have attracted tremendous attention for their good signal uniformity, chemical stability, and biocompatibility. Here, a new concept to design high sensitivity semiconducting SERS substrates through integration of both amorphous and nonstoichiometric features of WO3−x thin films is presented. The integration of these two features provides narrower bandgap, additional defect levels within the bandgap, stronger exciton resonance, and higher electronic density of states near the Fermi level. These characteristics lead to a synergy to promote the photoinduced charge transfer resonance between analytes and substrate by offering efficient routes of charge escaping and transferring as well as strong vibronic coupling, thus realizing high SERS activity on amorphous nonstoichiometric WO3−x films.

  50. M. Z. Li, X. C. Fan, Y. M. Gao, and T. Qiu*, “W18O49/Monolayer MoS2 Heterojunction-Enhanced Raman Scattering”, The Journal of Physical Chemistry Letters , vol. 10, iss. 14, pp. 4038 - 4044 (2019).



    Surface-enhanced Raman spectroscopy (SERS), a sensitive analytical technique that has single molecular sensitivity, has attracted continuous attention for both application and academic research. Semiconductor-based substrates with SERS activity present more practical applications, ranging from surface science to biological detection because of their lower cost and better biocompatibility compared with noble metals. However, the SERS performance of most semiconductor-based substrates is not significant. Herein, we propose the concept of semiconductor heterojunction-enhanced Raman scattering and design a vertical nanothickness heterojunction of W18O49/monolayer MoS2. As a result, the Raman signals of analyte Rhodamine 6G are detectable even with an ultralow concentration of 10–9 M on W18O49/monolayer MoS2 substrates. The enhancement factor is around 3.45 × 107. We confirmed from experiments and theory that the coupling of these two semiconductor materials could lead to dramatic enhancement of photoinduced charge-transfer processes, which enables giant heterojunction-enhanced Raman scattering.

  51. Y. M. Yang*, F. Kong, M. Z. Li, J. Y. Fan, and T. Qiu*, “Interaction between indium tin oxide nanoparticles and ferricytochrome c: Conformation, redox state, and adsorption scheme”, Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, vol. 213, pp. 64 – 72 (2019).



    The conformations and redox states of ferricytochromec, before and after adsorption onto the surface of the in-dium tin oxide (ITO) nanoparticles, are studied to reveal the interaction nature between the cytochromecandthe conducting metal oxide surface. The characterizations with resonance Raman scattering and UV–Vis absorp-tion reveal that the change of pH at moderate ionic strength induces transitions of conformations and redox-states, which suggests that there is intramolecular electron transfer. The conformations of the cytochromecspe-cies are maintained after adsorption onto or collision with the ITO surface, but the redox states change signifi-cantly, and the change depends on the surface structure of the ITO nanoparticle. The adsorption or collisionprocesses aregoverned by the pH-dependentelectrostaticinteractionbetween the proteins and the buffer anionsbound to the ITO surface. This adsorption scenario differs from the convention.

  52. X. Y. Hou, X. G. Luo, X. C. Fan, Z. H. Peng, and T. Qiu*, “Plasmon-coupled charge transfer in WO3−x semiconductor nanoarrays: toward highly uniform silver-comparable SERS platforms”, Physical Chemistry Chemical Physics, vol. 21, iss. 5, pp. 2611 – 2618 (2019).



    Transition metal oxide semiconductors have been explored in surface-enhanced Raman scattering (SERS) active substrates, yet their detection sensitivity and enhancement effects are inferior. What's more, the reported fabrication technique ignored the effects of the electromagnetic mechanisms and was far from satisfactory for practical applications. Herein, we report on a convenient nanotechnique to fabricate large-area hexagon plum-blossom-like WO3−x nanoarrays based on aluminum nanobowl array substrates. Localized surface plasmon resonance can be increased via adjusting the time of tungsten magnetron sputtering with H2 annealing treatment. The introduction of a double-switch experiment demonstrates that localized surface plasmon-coupled photoinduced charge transfer can not only increase SERS enhancement comparable to similar silver nanostructures but also implement a low limit of detection below 10−9 M. A triple-switch experiment offers specific rules in the molecular detection of WO3−x semiconductors and important guidance for the fabrication of SERS-active semiconducting platforms.

  53. Q. H. Jing, H. Zhang, H. Huang, X. C. Fan, Y. M. Zhang, X. Y. Hou, Q. Y. Xu, Z. H. Ni*,and T. Qiu*, “Ultrasonic exfoliated ReS2 nanosheets: fabrication and use as co-catalyst for enhancing photocatalytic efficiency of TiO2 nanoparticles under sunlight”, Nanotechnology, vol. 30, no. 18, Article Number: 184001 (2019).



    Rhenium disulfide (ReS2) is an interesting kind of transition metal dichalcogenide (TMD) because of its thickness-independent and suitable direct-bandgap structure, which could enable highly efficient solar-energy conversion efficiency. Here, we demonstrate an ultrasonic liquid exfoliation technique in combination with grinding to produce high quality ReS2 nanosheets (NSs) on a large scale. After combination with TiO2 nanoparticles, the co-catalytic performance of TiO2@ReS2 nanocomposites is investigated, which presents dramatically enhanced degradation activity of organic pigments under sunlight illumination in comparison with pure TiO2 nanoparticles. The underlying mechanism of enhanced photocatalytic activity can be attributed to improved separation efficiency of photogenerated electron–hole pairs in TiO2@ReS2 nanocomposites, which is confirmed by photoluminescence analysis and photoelectrochemical measurements. Our results demonstrate that the layered ReS2 NS is a promising two-dimensional supporting platform for photocatalysis and moreover it could also provide a new perspective on TMDs co-catalyst.

  54. B. R. Xu, X. Y. Zhang, Z. Tian, D. Han, X. C. Fan, Y. M. Chen, Z. F. Di, T. Qiu, and Y. F. Mei*, “Microdroplet-guided intercalation anddeterministic delamination towards intelligentrolling origami”, Nature Communications , vol. 10, Article Number: 5019 (2019).




Chinese Patents


  1. [发明授权]：罗正位，范兴策，邱腾，“具有表面增强拉曼散射功能的氧化钨基底及其制备方法”，授权公告号：CN106756853B，授权公告日：2019.03.12


  2. [发明授权]： 孔凡，程瑜，邱腾，“种基于三峰类配体二维金属有机框架材料及其制备方法和应用”，授权公告号：CN112029107B，授权公告日：2020.12.04


  3. [发明授权]：徐春祥，王茹，石增良，邱腾，“基于ZnO/AI荷壳纳米线的等离激元激光器及其制备方法”，授权公告号：CN112563881B，授权公告日：2021.03.26


  4. [发明授权]：孔凡，贾雪莉，付国东，丁收年，邱腾，“一种含8-轻基峰咻基团的咔哗多孔聚合物及其制备方法和应用”，授权公告号：CN113072687B，授权公告日：2021.07.06


  5. [发明授权]：孔凡，张淑婷，丁收年，邱腾，“一种含毗噬基共价有机框架材料及其制备方法和应用”，授权公告号：CN114957685B，授权公告日：2022.08.30