Co-reporter:Xiang Wang;Sheng-Chao Huang;Teng-Xiang Huang;Hai-Sheng Su;Jin-Hui Zhong;Zhi-Cong Zeng;Mao-Hua Li
Chemical Society Reviews 2017 vol. 46(Issue 13) pp:4020-4041
Publication Date(Web):2017/07/03
DOI:10.1039/C7CS00206H
Surface and interfaces play key roles in heterogeneous catalysis, electrochemistry and photo(electro)chemistry. Tip-enhanced Raman spectroscopy (TERS) combines plasmon-enhanced Raman spectroscopy with scanning probe microscopy to simultaneously provide a chemical fingerprint and morphological information for the sample at the nanometer spatial resolution. It is an ideal tool for achieving an in-depth understanding of the surface and interfacial processes, so that the relationship between structure and chemical performance can be established. We begin with the background of surfaces and interfaces and TERS, followed by a detailed discussion on some issues in experimental TERS, including tip preparation and TERS instrument configuration. We then focus on the progress of TERS for studying the surfaces and interfaces under different conditions, from ambient, to UHV, solid–liquid and electrochemical environments, followed by a brief introduction to the current understanding of the unprecedented high spatial resolution and surface selection rules. We conclude by discussing the future challenges for TERS practical applications in surfaces and interfaces.
Co-reporter:Weichun Ye;Hong Huang;Weiwei Yang;Xiang Wang;Cuiling Ren;Qiushi Hu;Yumin Li
Analyst (1876-Present) 2017 vol. 142(Issue 18) pp:3459-3467
Publication Date(Web):2017/09/08
DOI:10.1039/C7AN00675F
In shell-isolated nanoparticle (NP)-enhanced Raman spectroscopy (SHINERS), traditional metal oxide-based shells have inferior chemical inertness, they require strict preparation conditions, and lack specific groups, which lead to their poor selectivity toward target molecules. In this study, ultrathin and compact gold (Au)@polydopamine (PDA) SHINERS NPs were successfully fabricated by a simple self-polymerization technique. High wrapping tendency of PDA, a multifunctional biopolymer, favored the fabrication process. Au@PDA NPs exhibited a typical shell-isolated effect, i.e., Au@PDA NPs with a thick shell (more than 2.3 nm) showed a lower SERS activity, while those with an ultrathin (1.3 nm) shell exhibited higher SERS activity compared to uncoated Au NPs. The Au@PDA SHINERS substrate shows high performance in terms of sensitivity, uniformity, and stability. The relative standard deviations (RSDs) of SERS intensities from ten positions on the same substrate were less than 4%. Their Raman intensities dropped by only 15% over two months. More importantly, the Au@PDA (1.3 nm) SHINERS substrate exhibited high SERS activity for label-free and quantitative detection of benzotriazole (BTA), an important corrosion inhibitor, through utilizing a presumed π–π stacking interaction. A broad linear range from 10−4 to 10−8 M was achieved with a low detection limit (LOD) of 1 nM (0.119 μg L−1). The LOD was not only significantly lower than the maximum allowable level (20 μg L−1) of the Australian government water guide, but also lower than that of some modern methods such as fluorescence, liquid chromatography, and gas chromatography coupled with mass spectrometry. Furthermore, the substrate showed excellent discrimination against other compounds with a single aromatic ring. It is expected that the Au@PDA SHINERS substrate will offer great potential for analysis application in a complicated environmental system.
Co-reporter:Weichun Ye;Hong Huang;Weiwei Yang;Xiang Wang;Cuiling Ren;Qiushi Hu;Yumin Li
Analyst (1876-Present) 2017 vol. 142(Issue 18) pp:3459-3467
Publication Date(Web):2017/09/08
DOI:10.1039/C7AN00675F
In shell-isolated nanoparticle (NP)-enhanced Raman spectroscopy (SHINERS), traditional metal oxide-based shells have inferior chemical inertness, they require strict preparation conditions, and lack specific groups, which lead to their poor selectivity toward target molecules. In this study, ultrathin and compact gold (Au)@polydopamine (PDA) SHINERS NPs were successfully fabricated by a simple self-polymerization technique. High wrapping tendency of PDA, a multifunctional biopolymer, favored the fabrication process. Au@PDA NPs exhibited a typical shell-isolated effect, i.e., Au@PDA NPs with a thick shell (more than 2.3 nm) showed a lower SERS activity, while those with an ultrathin (1.3 nm) shell exhibited higher SERS activity compared to uncoated Au NPs. The Au@PDA SHINERS substrate shows high performance in terms of sensitivity, uniformity, and stability. The relative standard deviations (RSDs) of SERS intensities from ten positions on the same substrate were less than 4%. Their Raman intensities dropped by only 15% over two months. More importantly, the Au@PDA (1.3 nm) SHINERS substrate exhibited high SERS activity for label-free and quantitative detection of benzotriazole (BTA), an important corrosion inhibitor, through utilizing a presumed π–π stacking interaction. A broad linear range from 10−4 to 10−8 M was achieved with a low detection limit (LOD) of 1 nM (0.119 μg L−1). The LOD was not only significantly lower than the maximum allowable level (20 μg L−1) of the Australian government water guide, but also lower than that of some modern methods such as fluorescence, liquid chromatography, and gas chromatography coupled with mass spectrometry. Furthermore, the substrate showed excellent discrimination against other compounds with a single aromatic ring. It is expected that the Au@PDA SHINERS substrate will offer great potential for analysis application in a complicated environmental system.
Co-reporter:Zhi-Cong Zeng, Shu Hu, Sheng-Chao Huang, Yue-Jiao Zhang, Wei-Xing Zhao, Jian-Feng Li, Chaoyang Jiang, and Bin Ren
Analytical Chemistry 2016 Volume 88(Issue 19) pp:9381
Publication Date(Web):September 9, 2016
DOI:10.1021/acs.analchem.6b02739
Electrochemical Raman spectroscopy is a powerful molecular level diagnostic technique for in situ investigation of adsorption and reactions on various material surfaces. However, there is still a big room to improve the optical path to meet the increasing request of higher detection sensitivity and spatial resolution. Herein, we proposed a novel electrochemical Raman setup based on a water immersion objective. It dramatically reduces mismatch of the refractive index in the light path. Consequently, significant improvement in detection sensitivity and spatial resolution has been achieved from both Zemax simulation and the experimental results. Furthermore, the thickness of electrolyte layer could be expanded to 2 mm without any influence on the signal collection. Such a thick electrolyte layer allows a much normal electrochemical response during the spectroelectrochemical investigations of the methanol oxidation.
Co-reporter:Xiang Wang, Jin-Hui Zhong, Meng Zhang, Zheng Liu, De-Yin Wu, and Bin Ren
Analytical Chemistry 2016 Volume 88(Issue 1) pp:915
Publication Date(Web):December 3, 2015
DOI:10.1021/acs.analchem.5b03588
Controlling the packing structure and revealing the intermolecular interaction of self-assembled monolayers (SAMs) on solid surfaces are crucial for manipulating its properties. We utilized tip-enhanced Raman spectroscopy (TERS) to address the challenge in probing the subtle change of the intermolecular interaction during the assembly of a pyridine-terminated aromatic thiol on the single crystal Au(111) surface that cannot produce enhanced Raman signal, together with electrochemical methods to study the charge transfer properties of SAM. We observed that the aromatic C═C bond stretching vibration can be a marker to monitor the strength of the intermolecular interaction of SAMs, because this Raman peak is very sensitive to the intermolecular π–π stacking. Our results indicate that the SAM experiences a surface restructuring after the formation of a densely packed monolayer. We propose that the intermolecular electrostatic repulsion governs the restructuring when the packing density is high. The correlated TERS and electrochemical studies also suggest that the intermolecular interaction may have some impact on the charge transfer properties of SAM. This study provides a molecular-level insight into understanding and exploiting the intermolecular interactions toward better control over the assembling process and tuning the electrical properties of aromatic thiols.
Co-reporter:Kai-Qiang Lin, Jun Yi, Shu Hu, Juan-Juan Sun, Jue-Ting Zheng, Xiang Wang, and Bin Ren
ACS Photonics 2016 Volume 3(Issue 7) pp:
Publication Date(Web):May 31, 2016
DOI:10.1021/acsphotonics.6b00238
We report the observation of the undocumented visible one-photon photoluminescence (PL) of single silver nanorods excited by 532 and 633 nm continuous wave lasers with single-nanoparticle spectroscopy. We attribute the PL of silver nanorods to the intraband transition excited hot-electron radiative decay. The PL of silver nanorods closely resembles the corresponding LSPR scattering spectrum, and both are dependent on their aspect ratio. The good correlation between the quantitative PL intensity and the absorption cross section at the excitation wavelength of each nanorod leads to an aspect ratio independent PL quantum yield. The PL quantum yield of silver nanorods is similar to that of gold nanorods (10–6), indicating an efficient intraband excitation of hot electrons. The understanding of the PL mechanism of Ag nanorods points to the high-energy nature of the hot electrons excited via intraband transition, which has important indications in utilizing hot electrons for energy harvesting and photocatalysis.
Co-reporter:Kai-Qiang Lin, Jun Yi, Shu Hu, Bi-Ju Liu, Jun-Yang Liu, Xiang Wang, and Bin Ren
The Journal of Physical Chemistry C 2016 Volume 120(Issue 37) pp:20806-20813
Publication Date(Web):April 5, 2016
DOI:10.1021/acs.jpcc.6b02098
Surface-enhanced Raman spectroscopy (SERS) has attracted tremendous interest as a label-free highly sensitive analytical method. For optimization of SERS activity, it is highly important to systematically investigate the size effect of nanoparticles on the SERS enhancement, which appears to be challenging in experiment, as the localized surface plasmon resonance (LSPR) of nanoparticles also changes with the change of the particle size. This challenge can be overcome by utilizing the unique property of gold nanorods, whose LSPR wavelength can be controlled to be the same by properly choosing the size and aspect ratio of the nanorods. We obtained the correlated SEM images, scattering spectra, and SERS spectra on a home-built single nanoparticle spectroscopy system and systematically investigate the size effect on SERS of individual gold nanorods using the adsorbed malachite green isothiocyanate (MGITC) molecule as the probe molecule. The dark field scattering intensity was found to increase with the increase of the size of nanoparticles, whereas the SERS intensity increases with the decrease of the size as a result of the stronger lightning rod effect and weaker radiation damping. We further explored the size-dependent effect for the coupled nanorod dimer system. The SERS activity was also found to increase with a decrease of the particle size when the excitation is close to the LSPR wavelength. Understanding of the size effect on the local field enhancement may help to design and fabricate SERS substrate and TERS tips with high SERS activity.
Co-reporter:Jie Huang;Miao Guo;Hengte Ke;Cheng Zong;Gang Liu;He Shen;Yufei Ma;Xiaoyong Wang;Hailu Zhang;Zongwu Deng;Huabing Chen;Zhijun Zhang
Advanced Materials 2015 Volume 27( Issue 34) pp:5049-5056
Publication Date(Web):
DOI:10.1002/adma.201501942
Co-reporter:Li-Jia Xu; Zhi-Chao Lei; Jiuxing Li; Cheng Zong; Chaoyong James Yang
Journal of the American Chemical Society 2015 Volume 137(Issue 15) pp:5149-5154
Publication Date(Web):April 2, 2015
DOI:10.1021/jacs.5b01426
Direct, label-free detection of unmodified DNA is a great challenge for DNA analyses. Surface-enhanced Raman spectroscopy (SERS) is a promising tool for DNA analyses by providing intrinsic chemical information with a high sensitivity. To address the irreproducibility in SERS analysis that hampers reliable DNA detection, we used iodide-modified Ag nanoparticles to obtain highly reproducible SERS signals of single- and double-strand DNA in aqueous solutions close to physiological conditions. The phosphate backbone signal was used as an internal standard to calibrate the absolute signal of each base for a more reliable determination of the DNA structure, which has not been achieved before. Clear identification of DNA with single-base sensitivity and the observation of a hybridization event have been demonstrated.
Co-reporter:Zhi-Cong Zeng; Sheng-Chao Huang; De-Yin Wu; Ling-Yan Meng; Mao-Hua Li; Teng-Xiang Huang; Jin-Hui Zhong; Xiang Wang; Zhi-Lin Yang
Journal of the American Chemical Society 2015 Volume 137(Issue 37) pp:11928-11931
Publication Date(Web):September 9, 2015
DOI:10.1021/jacs.5b08143
Interfacial properties are highly important to the performance of some energy-related systems. The in-depth understanding of the interface requires highly sensitive in situ techniques that can provide fingerprint molecular information at nanometer resolution. We developed an electrochemical tip-enhanced Raman spectroscopy (EC-TERS) by introduction of the light horizontally to the EC-STM cell to minimize the optical distortion and to keep the TERS measurement under a well-controlled condition. We obtained potential-dependent EC-TERS from the adsorbed aromatic molecule on a Au(111) surface and observed a substantial change in the molecule configuration with potential as a result of the protonation and deprotonation of the molecule. Such a change was not observable in EC-SERS (surface-enhanced), indicating EC-TERS can more faithfully reflect the fine interfacial structure than EC-SERS. This work will open a new era for using EC-TERS as an important nanospectroscopy tool for the molecular level and nanoscale analysis of some important electrochemical systems including solar cells, lithium ion batteries, fuel cells, and corrosion.
Co-reporter:Cheng Zong; Chan-Juan Chen; Meng Zhang; De-Yin Wu
Journal of the American Chemical Society 2015 Volume 137(Issue 36) pp:11768-11774
Publication Date(Web):September 1, 2015
DOI:10.1021/jacs.5b07197
The pursuit of techniques with a high time resolution together with molecular signature information at the electrochemical interfaces has never stopped in order to explicitly monitor and understand the dynamic electrochemical processes. Here, we developed a transient electrochemical surface-enhanced Raman spectroscopy (TEC-SERS) to monitor the structural evolution of surface species at a time resolution that equals the transient electrochemical methods (e.g., cyclic voltammetry and chronoamperometry), so that the Raman signal with the molecular signature information and the electrochemical current signal can be precisely correlated. The technique was employed to study the redox process of nile blue on Ag surfaces. We revealed an interesting two-rate constant process and a peculiar increase of the absolute intensity during the reduction of nile blue on the Ag surface, which both related to the dissociation of nile blue aggregates and the follow-up reduction. Therefore, we were able to uncover the processes that are impossible to observe by conventional steady state SERS methods. The ability to provide a time resolution shorter than the charging time of the double layer capacitance with molecular fingerprint information has unprecedented significance for investigation of both reversible and irreversible electrochemical processes.
Co-reporter:Jia-Jia Chen, Ru-Ming Yuan, Jia-Min Feng, Qian Zhang, Jing-Xin Huang, Gang Fu, Ming-Sen Zheng, Bin Ren, and Quan-Feng Dong
Chemistry of Materials 2015 Volume 27(Issue 6) pp:2048
Publication Date(Web):February 26, 2015
DOI:10.1021/cm5044667
Sulfur and polysulfides play important roles on the environment and energy storage systems, especially in the recent hot area of high energy density of lithium–sulfur (Li–S) batteries. However, the further development of Li–S battery is still retarded by the lack of complete mechanistic understanding of the sulfur redox process. Herein we introduce a conductive Lewis base matrix which has the ability to enhance the battery performance of Li–S battery, via the understanding of the complicated sulfur redox chemistry on the electrolyte/carbon interface by a combined in operando Raman spectroscopy and density functional theory (DFT) method. The higher polysulfides, Li2S8, is found to be missing during the whole redox route, whereas the charging process of Li–S battery is ended up with the Li2S6. DFT calculations reveal that Li2S8 accepts electrons more readily than S8 and Li2S6 so that it is thermodynamically and kinetically unstable. Meanwhile, the poor adsorption behavior of Li2Sn on carbon surface further prevents the oxidization of Li2Sn back to S8 upon charging. Periodic DFT calculations show that the N-doped carbon surface can serve as conductive Lewis base “catalyst” matrix to enhance the adsorption energy of Li2Sn (n = 4–8). This approach allows the higher Li2Sn to be further oxidized into S8, which is also confirmed by in operando Raman spectroscopy. By recovering the missing link of Li2S8 in the whole redox route, a significant improvement of the S utilization and cycle stability even at a high sulfur loading (70%, m/m) in the composite on a simple super P carbon.
Co-reporter:Li-Kun Yang, Teng-Xiang Huang, Zhi-Cong Zeng, Mao-Hua Li, Xiang Wang, Fang-Zu Yang and Bin Ren
Nanoscale 2015 vol. 7(Issue 43) pp:18225-18231
Publication Date(Web):08 Oct 2015
DOI:10.1039/C5NR04263A
Reproducible fabrication of sharp gold- or silver-coated tips has become the bottleneck issue in tip-enhanced Raman spectroscopy, especially for atomic force microscopy (AFM)-based TERS. Herein, we developed a novel method based on pulsed electrodeposition to coat a thin gold layer over atomic force microscopy (AFM) tips to produce plasmonic TERS tips with high reproducibility. We systematically investigated the influence of the deposition potential and step time on the surface roughness and sharpness. This method allows the rational control of the radii of gold-coated TERS tips from a few to hundreds of nanometers, which allows us to systematically study the dependence of the TERS enhancement on the radius of the gold-coated AFM tip. The maximum TERS enhancement was achieved for the tip radius in the range of 60–75 nm in the gap mode. The coated gold layer has a strong adhesion with the silicon tip surface, which is highly stable in water, showing the great potential for application in the aqueous environment.
Co-reporter:Bi-Ju Liu, Kai-Qiang Lin, Shu Hu, Xiang Wang, Zhi-Chao Lei, Hai-Xin Lin, and Bin Ren
Analytical Chemistry 2015 Volume 87(Issue 2) pp:1058
Publication Date(Web):December 15, 2014
DOI:10.1021/ac503612b
Noble metal nanoparticles have unique localized surface plasmon resonance (LSPR), leading to their strong absorption and scattering in the visible light range. Up to date, the common practice in the selection of nanoparticles for a specific application is still based on the measured extinction spectra. This practice may be erroneous, because the extinction spectra contain both absorption and scattering contribution that may play different roles in different applications. It would be highly desirable to develop an efficient way to obtain the absorption and scattering spectra simultaneously. Herein, we develop a method to use the experimentally measured extinction and scattering signals to extract the absorption and scattering spectra that is in excellent agreement with that simulated by discrete dipole approximation (DDA). The heating curve measurement on the three types of gold nanorods, with almost the same extinction spectra but different absorption and scattering contribution, convincingly reveals an excellent correlation between the heating effect and the absorption strength rather than the extinction strength. The result demonstrates the importance to obtain the scattering and absorption spectra to predict the potential application for different types of nanoparticles, which in turn will screen efficiently nanoparticles for a specific application.
Co-reporter:Jun Hu, Qi-Min Gan, Yu-Ling Zhang, Bin Ren, Yong-Jun Li
Materials Chemistry and Physics 2015 Volume 163() pp:529-536
Publication Date(Web):1 August 2015
DOI:10.1016/j.matchemphys.2015.08.009
•Au nano-coral (3DGN) was electrodeposited simply with the guidance of NH4+NH4+.•3DGN was able to be decomposed into individual (111)-orientated Au nanocrystals.•This technique provides a way to produce (111)-orientated Au nanocrystals.•Optimized 3DGN exhibits intense enhancement and reproducibility of SERS.In this work, a reliable surface-enhanced Raman scattering (SERS)-active substrate, three-dimensional gold nano-coral structure (3DGN), was prepared simply by one-step electrodeposition in HAuCl4 and NH4Br solution without the confinement of templates or the guidance of organic surfactants. The final morphology and thickness of 3DGN depend on the concentration of NH4Br and the electrodeposition time. When the concentration of NH4Br was 10.0 mmol/L, as-prepared 3DGN has a uniform structural morphology and exhibits the best SERS activity, spatial uniformity and reproducibility towards rhodamine 6G (R6G). The relative standard deviation (RSD) of the spot-to-spot SERS signals is about 10% according to the intensity of 1506 cm−1 Raman vibration modes of R6G, meeting the requirement of SERS substrate for analytic detection. Additionally, the resulting 3DGN could be decomposed into individual (111)-orientated Au nanocrystals under ultrasonication, providing a facile approach to produce Au nanocrystals.
Co-reporter:De-Yin Wu;Meng Zhang;Liu-Bin Zhao;Yi-Fan Huang
Science China Chemistry 2015 Volume 58( Issue 4) pp:574-585
Publication Date(Web):2015 April
DOI:10.1007/s11426-015-5316-y
Nanoscale noble metals can exhibit excellent photochemical and photophysical properties, due to surface plasmon resonance (SPR) from specifically collective electronic excitations on these metal surfaces. The SPR effect triggers many new surface processes, including radiation and radiationless relaxations. As for the radiation process, the SPR effect causes the significant focus of light and enormous enhancement of the local surface optical electric field, as observed in surface-enhanced Raman spectroscopy (SERS) with very high detection sensitivity (to the single-molecule level). SERS is used to identify surface species and characterize molecular structures and chemical reactions. For the radiationless process, the SPR effect can generate hot carriers, such as hot electrons and hot holes, which can induce and enhance surface chemical reactions. Here, we review our recent work and related literature on surface catalytic-coupling reactions of aromatic amines and aromatic nitro compounds on nanostructured noble metal surfaces. Such reactions are a type of novel surface plasmon-enhanced chemical reaction. They could be simultaneously characterized by SERS when the SERS signals are assigned. By combining the density functional theory (DFT) calculations and SERS experimental spectra, our results indicate the possible pathways of the surface plasmon-enhanced photochemical reactions on nanostructures of noble metals. To construct a stable and sustainable system in the conversion process of the light energy to the chemical energy on nanoscale metal surfaces, it is necessary to simultaneously consider the hot electrons and the hot holes as a whole chemical reaction system.
Co-reporter:Wei Shen;Xuan Lin; Chaoyang Jiang;Chaoyu Li;Haixin Lin;Jingtao Huang;Shuo Wang;Dr. Guokun Liu; Xiaomei Yan; Qiling Zhong; Bin Ren
Angewandte Chemie International Edition 2015 Volume 54( Issue 25) pp:7308-7312
Publication Date(Web):
DOI:10.1002/anie.201502171
Abstract
Quantitative analysis is a great challenge in surface-enhanced Raman scattering (SERS). Core-molecule-shell nanoparticles with two components in the molecular layer, a framework molecule to form the shell, and a probe molecule as a Raman internal standard, were rationally designed for quantitative SERS analysis. The signal of the embedded Raman probe provides effective feedback to correct the fluctuation of samples and measuring conditions. Meanwhile, target molecules with different affinities can be adsorbed onto the shell. The quantitative analysis of target molecules over a large concentration range has been demonstrated with a linear response of the relative SERS intensity versus the surface coverage, which has not been achieved by conventional SERS methods.
Co-reporter:Bo-Wen Liu, Xu Yao, Liang Zhang, Hai-Xin Lin, Shu Chen, Jin-Hui Zhong, Shou Liu, Lei Wang, and Bin Ren
ACS Photonics 2015 Volume 2(Issue 12) pp:
Publication Date(Web):November 23, 2015
DOI:10.1021/acsphotonics.5b00650
Delicate control of the surface plasmon resonance (SPR) line shapes is crucial for the development of nanoplasmonics with dedicated applications. In this paper, we develop a method to fabricate large-scale periodic structures with significantly different plasmonic properties by the holographic lithography method. We show that SPR line shapes can be controllably engineered from a broad superradiant line shape to an asymmetrical Fano-type resonance, as well as an ultranarrow subradiant mode, which are clearly correlated with the structural parameter (morphology) of the fabricated structures. The wavelength of the SPR band can be tuned from the visible to near-infrared region by changing the incident angle. The nanostructures fabricated by the present method show a clear correlation between the morphology of plasmonic structures and SPR line shapes, which can serve as an efficient platform for engineering SPR line shapes for specific applications. Most importantly, the capability to produce structures of large area further supports the unprecedented opportunity to push these plasmonic structures fabricated by holographic lithography toward real applications.
Co-reporter:Hao Yang;Lan-Qi He;Yu-Wen Hu;Dr. Xihong Lu; Gao-Ren Li;Dr. Biju Liu; Bin Ren; Yexiang Tong;Dr. Ping-Ping Fang
Angewandte Chemie International Edition 2015 Volume 54( Issue 39) pp:11462-11466
Publication Date(Web):
DOI:10.1002/anie.201505985
Abstract
The surface plasmon resonance (SPR) induced photothermal and photoelectrocatalysis effects are crucial for catalytic reactions in many areas. However, it is still difficult to distinguish these two effects quantitatively. Here we used surface-enhanced Raman scattering (SERS) to detect the photothermal and photoelectrocatalytic effects induced by SPR from Au core Pt shell Nanoparticles (Au@Pt NPs), and calculated the quantitative contribution of the ratio of the photothermal and photoelectrocatalysis effects towards the catalytic activity. The photothermal effect on the nanoparticle surface after illumination is detected by SERS. The photoelectrocatalytic effect generated from SPR is proved by SERS with a probe molecule of p-aminothiophenol (PATP).
Co-reporter:Wei Shen;Xuan Lin; Chaoyang Jiang;Chaoyu Li;Haixin Lin;Jingtao Huang;Shuo Wang;Dr. Guokun Liu; Xiaomei Yan; Qiling Zhong; Bin Ren
Angewandte Chemie 2015 Volume 127( Issue 25) pp:7416-7420
Publication Date(Web):
DOI:10.1002/ange.201502171
Abstract
Quantitative analysis is a great challenge in surface-enhanced Raman scattering (SERS). Core-molecule-shell nanoparticles with two components in the molecular layer, a framework molecule to form the shell, and a probe molecule as a Raman internal standard, were rationally designed for quantitative SERS analysis. The signal of the embedded Raman probe provides effective feedback to correct the fluctuation of samples and measuring conditions. Meanwhile, target molecules with different affinities can be adsorbed onto the shell. The quantitative analysis of target molecules over a large concentration range has been demonstrated with a linear response of the relative SERS intensity versus the surface coverage, which has not been achieved by conventional SERS methods.
Co-reporter:Hao Yang;Lan-Qi He;Yu-Wen Hu;Dr. Xihong Lu; Gao-Ren Li;Dr. Biju Liu; Bin Ren; Yexiang Tong;Dr. Ping-Ping Fang
Angewandte Chemie 2015 Volume 127( Issue 39) pp:11624-11628
Publication Date(Web):
DOI:10.1002/ange.201505985
Abstract
The surface plasmon resonance (SPR) induced photothermal and photoelectrocatalysis effects are crucial for catalytic reactions in many areas. However, it is still difficult to distinguish these two effects quantitatively. Here we used surface-enhanced Raman scattering (SERS) to detect the photothermal and photoelectrocatalytic effects induced by SPR from Au core Pt shell Nanoparticles (Au@Pt NPs), and calculated the quantitative contribution of the ratio of the photothermal and photoelectrocatalysis effects towards the catalytic activity. The photothermal effect on the nanoparticle surface after illumination is detected by SERS. The photoelectrocatalytic effect generated from SPR is proved by SERS with a probe molecule of p-aminothiophenol (PATP).
Co-reporter:Jin-Hui Zhong ; Jie Zhang ; Xi Jin ; Jun-Yang Liu ; Qiongyu Li ; Mao-Hua Li ; Weiwei Cai ; De-Yin Wu ; Dongping Zhan
Journal of the American Chemical Society 2014 Volume 136(Issue 47) pp:16609-16617
Publication Date(Web):October 28, 2014
DOI:10.1021/ja508965w
Improving electrochemical activity of graphene is crucial for its various applications, which requires delicate control over its geometric and electronic structures. We demonstrate that precise control of the density of vacancy defects, introduced by Ar+ irradiation, can improve and finely tune the heterogeneous electron transfer (HET) rate of graphene. For reliable comparisons, we made patterns with different defect densities on a same single layer graphene sheet, which allows us to correlate defect density (via Raman spectroscopy) with HET rate (via scanning electrochemical microscopy) of graphene quantitatively, under exactly the same experimental conditions. By balancing the defect induced increase of density of states (DOS) and decrease of conductivity, the optimal HET rate is attained at a moderate defect density, which is in a critical state; that is, the whole graphene sheet becomes electronically activated and, meanwhile, maintains structural integrity. The improved electrochemical activity can be understood by a high DOS near the Fermi level of defective graphene, as revealed by ab initio simulation, which enlarges the overlap between the electronic states of graphene and the redox couple. The results are valuable to promote the performance of graphene-based electrochemical devices. Furthermore, our findings may serve as a guide to tailor the structure and properties of graphene and other ultrathin two-dimensional materials through defect density engineering.
Co-reporter:Xiao-Shan Zheng, Pei Hu, Yan Cui, Cheng Zong, Jia-Min Feng, Xin Wang, and Bin Ren
Analytical Chemistry 2014 Volume 86(Issue 24) pp:12250
Publication Date(Web):November 24, 2014
DOI:10.1021/ac503404u
Local microenvironment pH sensing is one of the key parameters for the understanding of many biological processes. As a noninvasive and high sensitive technique, surface-enhanced Raman spectroscopy (SERS) has attracted considerable interest in the detection of the local pH of live cells. We herein develop a facile way to prepare Au-(4-MPy)-BSA (AMB) pH nanosensor. The 4-MPy (4-mercaptopyridine) was used as the pH sensing molecule. The modification of the nanoparticles with BSA not only provides a high sensitive response to pH changes ranging from pH 4.0 to 9.0 but also exhibits a high sensitivity and good biocompatibility, stability, and reliability in various solutions (including the solutions of high ionic strength or with complex composition such as the cell culture medium), both in the aggregation state or after long-term storage. The AMB pH nanosensor shows great advantages for reliable intracellular pH analysis and has been successfully used to monitor the pH distribution of live cells and can address the grand challenges in SERS-based pH sensing for practical biological applications.
Co-reporter:Li-Jia Xu, Cheng Zong, Xiao-Shan Zheng, Pei Hu, Jia-Min Feng, and Bin Ren
Analytical Chemistry 2014 Volume 86(Issue 4) pp:2238
Publication Date(Web):January 24, 2014
DOI:10.1021/ac403974n
Proteins perform vital functional and structural duties in living systems, and the in-depth investigation of protein in its native state is one of the most important challenges in the postgenomic era. Surface-enhanced Raman spectroscopy (SERS) can provide the intrinsic fingerprint information of samples with ultrahigh sensitivity but suffers from the reproducibility and reliability issues. In this paper, we proposed an iodide-modified Ag nanoparticles method (Ag IMNPs) for label-free detection of proteins. The silver nanoparticles provide the huge enhancement to boost the Raman signal of proteins, and the coated iodide layer offers a barrier to prevent the direct interaction between the proteins and the metal surface, helping to keep the native structures of proteins. With this method, highly reproducible and high-quality SERS signals of five typical proteins (lysozyme, avidin, bovine serum albumin, cytochrome c, and hemoglobin) have been obtained, and the SERS features of the proteins without chromophore were almost identical to the respective normal Raman spectra. This unique feature allows the qualitative identification of them by simply taking the intensity ratio of the Raman peaks of tryptophan to phenylalanine residues. We further demonstrated that the method can also be used for label-free multiplex analysis of protein mixture as well as to study the dynamic process of protein damage stimulated by hydrogen peroxide. This method proves to be very promising for further applications in proteomics and biomedical research.
Co-reporter:Dr. Yi-Fan Huang;Meng Zhang;Liu-Bin Zhao;Dr. Jia-Min Feng;Dr. De-Yin Wu;Dr. Bin Ren;Dr. Zhong-Qun Tian
Angewandte Chemie International Edition 2014 Volume 53( Issue 9) pp:2353-2357
Publication Date(Web):
DOI:10.1002/anie.201310097
Abstract
Surface plasmon resonances (SPRs) have been found to promote chemical reactions. In most oxidative chemical reactions oxygen molecules participate and understanding of the activation mechanism of oxygen molecules is highly important. For this purpose, we applied surface-enhanced Raman spectroscopy (SERS) to find out the mechanism of SPR-assisted activation of oxygen, by using p-aminothiophenol (PATP), which undergoes a SPR-assisted selective oxidation, as a probe molecule. In this way, SPR has the dual function of activating the chemical reaction and enhancing the Raman signal of surface species. Both experiments and DFT calculations reveal that oxygen molecules were activated by accepting an electron from a metal nanoparticle under the excitation of SPR to form a strongly adsorbed oxygen molecule anion. The anion was then transformed to Au or Ag oxides or hydroxides on the surface to oxidize the surface species, which was also supported by the heating effect of the SPR. This work points to a promising new era of SPR-assisted catalytic reactions.
Co-reporter:Xiang Wang, Maohua Li, Lingyan Meng, Kaiqiang Lin, Jiamin Feng, Tengxiang Huang, Zhilin Yang, and Bin Ren
ACS Nano 2014 Volume 8(Issue 1) pp:528
Publication Date(Web):December 16, 2013
DOI:10.1021/nn405073h
Wide applications of surface plasmon resonance rely on the in-depth understanding of the near-field distribution over a metallic nanostructure. However, precisely locating the strongest electric field in a metallic nanostructure still remains a great challenge in experiments because the field strength decays exponentially from the surface. Here, we demonstrate that the hot spot position for gold nanoparticles over a metal film can be precisely located using surface-enhanced Raman spectroscopy (SERS) by rationally choosing the probe molecules and excitation wavelengths. The finite difference time domain simulation verifies the experimental results and further reveals that the enhancement for the above system is sensitive to the distance between nanoparticles and the metal film but insensitive to the distance of nanoparticles. On the basis of this finding, we propose and demonstrate an approach of using a nanoparticles-on-metal film substrate as a uniform SERS substrate. This work provides a convenient way to probe the location of strong near-field enhancement with SERS and will have important implications in both surface analysis and surface plasmonics.Keywords: gold film; hot spot; nanoparticle; near-field distribution; surface plasmon resonance; uniform SERS substrate
Co-reporter:Xiao-Shan Zheng ; Pei Hu ; Jin-Hui Zhong ; Cheng Zong ; Xiang Wang ; Bi-Ju Liu
The Journal of Physical Chemistry C 2014 Volume 118(Issue 7) pp:3750-3757
Publication Date(Web):January 30, 2014
DOI:10.1021/jp409711r
A facile procedure was introduced to prepare uniform and highly active substrates assembled with gold nanoparticles for surface-enhanced Raman spectroscopy (SERS). The laser power and time dependent SERS study of 4-mercaptopyridine (4-MPy) adsorbed on this substrate was investigated. The relative intensity of the characteristic Raman peak pair (1575 and 1610 cm–1) was found to change with the laser power and the exposure time. The spectral changes may originate from change in the fraction of the double-end-bonded and the single-end-bonded states of 4-Mpy adsorbed on the gold nanoparticle-assembled substrate. In addition, this study offers a way to avoid the effect of laser power to achieve reliable spectral response to other factors.
Co-reporter:Hai-Xin Lin, Jie-Ming Li, Bi-Ju Liu, De-Yu Liu, Jinxuan Liu, Andreas Terfort, Zhao-Xiong Xie, Zhong-Qun Tian and Bin Ren
Physical Chemistry Chemical Physics 2013 vol. 15(Issue 12) pp:4130-4135
Publication Date(Web):16 Jan 2013
DOI:10.1039/C3CP43857K
Surface-enhanced Raman spectroscopy (SERS) benefits from the enhanced electromagnetic field of the localized surface plasmon resonance effect of metallic (especially coinage metals) nanoparticles or nanostructures. The detection sensitivity and reproducibility of SERS measurement appear to be the two critical issues in SERS. To solve the problem associated with traditional nanoparticle aggregates and SERS substrates, we propose in this work single particle SERS. We prepared uniform gold microspheres with controllable size and surface roughness using an etching-assisted seed-mediated method. Single particle dark-field spectroscopy and SERS measurements show that particles with a larger roughness give a stronger SERS signal, but still retain a good reproducibility. This study points to the promising future of the practical application of the single particle SERS technique for trace analysis.
Co-reporter:Jin-Hui Zhong, Jun-Yang Liu, Qiongyu Li, Mian-Gang Li, Zhi-Cong Zeng, Shu Hu, De-Yin Wu, Weiwei Cai, Bin Ren
Electrochimica Acta 2013 110() pp: 754-761
Publication Date(Web):
DOI:10.1016/j.electacta.2013.04.004
Co-reporter:Yi-Fan Huang, De-Yin Wu, Hong-Ping Zhu, Liu-Bin Zhao, Guo-Kun Liu, Bin Ren and Zhong-Qun Tian
Physical Chemistry Chemical Physics 2012 vol. 14(Issue 24) pp:8485-8497
Publication Date(Web):22 May 2012
DOI:10.1039/C2CP40558J
p-aminothiophenol (PATP) is an important molecule for surface-enhanced Raman spectroscopy (SERS). It can strongly interact with metallic SERS substrates and produce very strong SERS signals. It is a molecule that has often been used for mechanistic studies of the SERS mechanism as the photon-driven charge transfer (CT) mechanism is believed to be present for this molecule. Recently, a hot debate over the SERS behavior of PATP was triggered by our finding that PATP can be oxidatively transformed into 4,4′-dimercaptoazobenzene (DMAB), which gives a SERS spectra of so-called “b2 modes”. In this perspective, we will give a general overview of the SERS mechanism and the current status of SERS studies on PATP. We will then demonstrate with our experimental and theoretical evidence that it is DMAB which contributes to the characteristic SERS behavior in the SERS spectra of PATP and analyze some important experimental phenomena in the framework of the surface reaction instead of the contribution “b2 modes”. We will then point out the existing challenges of the present system. A clear understanding of the reaction mechanism for nitrobenzene or aromatic benzene will be important to not only understand the SERS mechanism but to also provide an economic way of producing azo dyes with a very high selectivity and conversion rate.
Co-reporter:Yan Cui, Xiao-Shan Zheng, Bin Ren, Rui Wang, Jun Zhang, Ning-Shao Xia and Zhong-Qun Tian
Chemical Science 2011 vol. 2(Issue 8) pp:1463-1469
Publication Date(Web):23 Jun 2011
DOI:10.1039/C1SC00242B
The increasing application of nanomaterials in biosensor and imaging sets a higher demand on the multifunctionalities of nanomaterials for obtaining multiple parameters of a same system under a same condition. In this work, multifunctional Au@organosilica nanoparticles with high stability were conveniently synthesized by direct hydrolyzing of 3-mercaptopropyltriethoxysilane in an aqueous solution in the presence of a Au core. Modification of the Au core with Raman reporters and the organosilica shell with fluorophore before and after the hydrolysis, respectively, produces multifunctional nanoparticles exhibiting Rayleigh scattering of the Au core, fluorescence signals of the fluorophores and surface-enhanced Raman scattering (SERS) of the Raman reporters. The nanoparticles can be used as multimodal tracers for living cell imaging and related biological research.
Co-reporter:Jia-Yi Huang, Cheng Zong, Li-Jia Xu, Yan Cui and Bin Ren
Chemical Communications 2011 vol. 47(Issue 20) pp:5738-5740
Publication Date(Web):18 Apr 2011
DOI:10.1039/C0CC05323F
Iodide adsorption and electrochemical negative potential desorption were proposed and compared to obtain clean SERS substrates. The two methods can effectively eliminate the interference of surface impurities in the SERS detection. SERS signals of membranes of living cells with a good reproducibility have been obtained.
Co-reporter:Yi-Fan Huang ; Hong-Ping Zhu ; Guo-Kun Liu ; De-Yin Wu ; Bin Ren ;Zhong-Qun Tian
Journal of the American Chemical Society 2010 Volume 132(Issue 27) pp:9244-9246
Publication Date(Web):June 8, 2010
DOI:10.1021/ja101107z
Surface-enhanced Raman spectroscopy (SERS) has long been considered as a noninvasive technique that can obtain the fingerprint vibrational information of surface species. We demonstrated in this paper that a laser with a power level considered to be low in the traditional SERS measurement can already lead to a significant surface reaction. para-Aminothiophenol, an important probe molecule in SERS, was found to be oxidized to form 4,4′-dimercaptoazobenzene (DMAB) on a roughened silver surface during the SERS measurement. The assumption was confirmed experimentally by surface mass spectroscopy and SERS as well as electrochemistry of the synthesized DMAB, which agrees well with theoretical calculations. A defocusing method was used to avoid the laser induced surface reaction and perform reliable SERS characterization and identification, which can effectively avoid erroneous interpretation of the distorted experimental result.
Co-reporter:Yi-Min Fang;Zhi-Bin Lin;Yong-Ming Zeng;Wen-Kai Chen ;Guo-Nan Chen ;Jian-Jun Sun ;Zhong-Qun Tian
Chemistry - A European Journal 2010 Volume 16( Issue 23) pp:6766-6770
Publication Date(Web):
DOI:10.1002/chem.201000068
Co-reporter:Yi-Fan Huang;Nai-Ning Yin;Xiang Wang;De-Yin Wu Dr., Dr. ;Zhong-Qun Tian Dr.
Chemistry - A European Journal 2010 Volume 16( Issue 5) pp:1449-1453
Publication Date(Web):
DOI:10.1002/chem.200902199
Co-reporter:Li Cui ; De-Yin Wu ; An Wang ; Bin Ren ;Zhong-Qun Tian
The Journal of Physical Chemistry C 2010 Volume 114(Issue 39) pp:16588-16595
Publication Date(Web):September 14, 2010
DOI:10.1021/jp1055717
In an attempt to understand the single-molecule SERS of some small nonresonant molecules, such as adenine, it is inevitable to include the chemical enhancement mechanism to provide additional enhancement to the electromagnetic mechanism, although it may be much smaller than the electromagnetic field enhancement. We will report here the first experimental investigation of the charge-transfer (CT) enhancement of protonated adenine molecules on Rh and Pd by performing the potential-dependent SERS using one UV laser (325 nm) and two visible lasers (514.5 and 632.8 nm). A UV laser displays a significant role in the verification of the CT process due to its much larger photon energy and thus a much larger shift of potential of the maximum SERS intensity (Emax) than visible lasers. We find a well-discernible Emax and a linear relationship between Emax and the photon energy of the laser for adenine on both Rh and Pd surfaces. The Emax was found to shift positively with the increasing photon energy, which strongly indicates an electron transfer from the Ef of Rh and Pd to the lowest unoccupied orbital of adenine molecules. In addition, different contributions of CT enhancement to adenine Raman bands are also briefly discussed. By analyzing the wavelength-dependent intensity change and UV−vis absorption spectroscopy, we propose the contribution of preresonance Raman enhancement to the UV-SERS signal for the band at around 1330 cm−1. The present study demonstrates that the use of a UV laser opens a promising way to understand the enhancement mechanism, especially the chemical enhancement mechanism.
Co-reporter:MuDe Zhuang;Zheng Liu;ZhongQun Tian
Science China Chemistry 2010 Volume 53( Issue 2) pp:426-431
Publication Date(Web):2010 February
DOI:10.1007/s11426-010-0068-1
Tip-enhanced Raman spectroscopy (TERS) has been used to obtain the Raman signal of surface species on silicon single crystal surfaces without the necessity for surface enhancement by addition of Ag nanoparticles. By illuminating the hydrogenterminated silicon surface covered with a droplet of 4-vinylpyridine with UV light, a 4-ethylpyridine modified silicon surface can be easily obtained. By bringing a scanning tunneling microscope (STM) Au tip with a nanoscale tip apex to a distance of ca. 1 nm from the modified silicon surface, enhanced Raman signals of the silicon phonon vibrations and the surface-bonded 4-ethylpyridine were obtained. The Raman enhancement factor was estimated to be close to 107. By comparing the surface-enhanced Raman scattering (SERS) signal obtained after surface enhancement with Ag nanoparticles and the TERS signal of the surface, the advantage of TERS over SERS for characterizing the surface species on substrates becomes apparent: TERS readily affords vibrational information about the system without disturbing it by surface enhancement. In this sense, TERS can be considered a truly non-invasive tool which is ideal for characterizing the actual surface species on substrates.
Co-reporter:Zhi-Bin Lin, Bu-Gao Xie, Jing-Hua Tian, Yong-An Tang, Jian-Jun Sun, Guo-Nan Chen, Bin Ren, Bing-Wei Mao, Zhong-Qun Tian
Journal of Electroanalytical Chemistry 2009 Volume 636(1–2) pp:74-79
Publication Date(Web):15 November 2009
DOI:10.1016/j.jelechem.2009.09.014
The adsorption behavior of uracil, an excellent ligand in cyanide-free silver plating on silver electrodes was studied with potential-dependent surface-enhanced Raman spectroscopy (SERS). Uracil was adsorbed at the silver surface with N3-deprotonated tautomer at pH 10.2, while with N1- and N3-deprotonated tautomers at pH 13.6. Uracil and additive polyethyleneimine (PEI) exhibit a co-adsorption behavior that holds the same tendency as their adsorption on the silver surfaces alone. The effect of PEI on silver plating process is proposed from SERS and electrochemical analysis. PEI, acted as an efficient suppressor and grain refiner in this silver plating bath, was further confirmed by the AFM micrographs.
Co-reporter:Xiu-Mei Lin;Yan Cui;Yan-Hui Xu
Analytical and Bioanalytical Chemistry 2009 Volume 394( Issue 7) pp:1729-1745
Publication Date(Web):2009 August
DOI:10.1007/s00216-009-2761-5
After over 30 years of development, surface-enhanced Raman spectroscopy (SERS) is now facing a very important stage in its history. The explosive development of nanoscience and nanotechnology has assisted the rapid development of SERS, especially during the last 5 years. Further development of surface-enhanced Raman spectroscopy is mainly limited by the reproducible preparation of clean and highly surface enhanced Raman scattering (SERS) active substrates. This review deals with some substrate-related issues. Various methods will be introduced for preparing SERS substrates of Ag and Au for analytical purposes, from SERS substrates prepared by electrochemical or vacuum methods, to well-dispersed Au or Ag nanoparticle sols, to nanoparticle thin film substrates, and finally to ordered nanostructured substrates. Emphasis is placed on the analysis of the advantages and weaknesses of different methods in preparing SERS substrates. Closely related to the application of SERS in the analysis of trace sample and unknown systems, the existing cleaning methods for SERS substrates are analyzed and a combined chemical adsorption and electrochemical oxidation method is proposed to eliminate the interference of contaminants. A defocusing method is proposed to deal with the laser-induced sample decomposition problem frequently met in SERS measurement to obtain strong signals. The existing methods to estimate the surface enhancement factor, a criterion to characterize the SERS activity of a substrate, are analyzed and some guidelines are proposed to obtain the correct enhancement factor.
Co-reporter:Zhi-Bin Lin, Jing-Hua Tian, Bu-Gao Xie, Yong-An Tang, Jian-Jun Sun, Guo-Nan Chen, Bin Ren, Bing-Wei Mao and Zhong-Qun Tian
The Journal of Physical Chemistry C 2009 Volume 113(Issue 21) pp:9224-9229
Publication Date(Web):2017-2-22
DOI:10.1021/jp809761f
In this paper, 2-hydroxypyridine (2-HP) and polyethyleneimine (PEI) were selected as ligand and additive, respectively, in a cyanide-free silver electroplating bath. Adsorption behaviors of 2-HP and PEI at silver electrodes were investigated by means of potential-dependent surface-enhanced Raman spectroscopy (SERS). The adsorption configuration variations of 2-HP and PEI at the silver surface with the negative shift of potential were discussed according to the SERS analysis. The possible effect of 2-HP and PEI on the silver electroplating process was also proposed. In the silver electroplating process, the SERS signal variations of 2-HP with the negative shift of potential were mainly due to the deposits’ morphology change. In the presence of PEI, fine grains and smoother surfaces are observed from the images of atomic force microscopy of the silver deposits.
Co-reporter:De-Yin Wu, Jian-Feng Li, Bin Ren and Zhong-Qun Tian
Chemical Society Reviews 2008 vol. 37(Issue 5) pp:1025-1041
Publication Date(Web):03 Apr 2008
DOI:10.1039/B707872M
This tutorial review first describes the early history of SERS as the first SERS spectra were obtained from an electrochemical cell, which led to the discovery of the SERS effect in mid-1970s. Up to date, over 500 papers have been published on various aspects of SERS from electrochemical systems. We then highlight important features of electrochemical SERS (EC-SERS). There are two distinctively different properties of electric fields, the electromagnetic field and static electrochemical field, co-existing in electrochemical systems with various nanostructures. Both chemical and physical enhancements can be influenced to some extent by applying an electrode potential, which makes EC-SERS one of the most complicated systems in SERS. Great efforts have been made to comprehensively understand SERS and analyze EC-SERS spectra on the basis of the chemical and physical enhancement mechanisms in order to provide meaningful information for revealing the mechanisms of electrochemical adsorption and reaction. The EC-SERS experiments and applications are then discussed from preparation of nanostructured electrodes to investigation of SERS mechanisms and from characterization of adsorption configuration to elucidation of electrochemical reaction mechanisms. Finally, prospective developments of EC-SERS in substrates, methods and theory are discussed.
Co-reporter:Ming-De Li, Yan Cui, Min-Xia Gao, Jia Luo, Bin Ren and Zhong-Qun Tian
Analytical Chemistry 2008 Volume 80(Issue 13) pp:5118
Publication Date(Web):May 20, 2008
DOI:10.1021/ac8003083
Surface-enhanced Raman spectroscopy (SERS) has received renewed interest in recent years in fields such as trace analysis, biorelated diagnosis, and living cell study. However, the interference of impurities left on the surface from the preparation process of substrates or adsorbed from the ambient environment limits to some extent the application of SERS for analysis of trace or unknown samples. In the present paper, we propose a method to prepare clean SERS substrates by a combined method of chemical adsorption of iodide on the Au surface to remove the surface impurities and electrochemical oxidation of the adsorbed iodide to obtain a clean and impurity-free surface for SERS measurement. Time-dependent control experiment of untreated and treated substrate reveals that this method is very effective in obtaining substrates free of impurities. SERS mapping demonstrates the SERS activity of the substrate is homogeneous over the whole surface. The obtained clean substrate enables us to study the structures of the cell membrane with SERS and even to perform SERS mapping to visualize the distribution of amino acids over the membrane of a living cell.
Co-reporter:Xiumei Lin, Xiang Wang, Zheng Liu, Bin Ren
Acta Physico-Chimica Sinica 2008 Volume 24(Issue 11) pp:1941-1945
Publication Date(Web):November 2008
DOI:10.1016/S1872-1508(08)60075-3
By assembling polystyrene microspheres on a sample surface, the surface Raman signal could be enhanced. The dependence of the enhancement effect on the size of microspheres was systematically investigated and it was found that microspheres with a diameter of 3.00 μm showed the highest enhancement of ca 5 folds. By utilizing the enhancement effect of the microspheres, the surface Raman intensity of malachite green isothiocyanate (MGITC) adsorbed on Au(111) surface could be enhanced by 20 folds, indicating that this method could effectively improve the detection sensitivity of surface Raman spectroscopy for the adsorbed species on single crystal surface. The later signal increment corresponds to the Raman enhancement effect of nearly 3 orders of magnitude. The enhancement effect is mainly owing to the formation of nanojets when a laser is focused on the microspheres of appropriate diameter. The formation of nanojets will lead to the highly localized electromagnetic field, which will then significantly enhance the Raman process in the nanojets. The main reason for obtaining different enhancements on two types of samples was analyzed.
Co-reporter:Zhong-Qun Tian, Bin Ren, Jian-Feng Li and Zhi-Lin Yang
Chemical Communications 2007 (Issue 34) pp:3514-3534
Publication Date(Web):04 Apr 2007
DOI:10.1039/B616986D
Surface-enhanced Raman scattering (SERS) was discovered three decades ago and has gone through a tortuous pathway to develop into a powerful diagnostic technique. Recently, the lack of substrate, surface and molecular generalities of SERS has been circumvented to a large extent by devising and utilizing various nanostructures by many groups including ours. This article aims to present our recent approaches of utilizing the borrowing SERS activity strategy mainly through constructing two types of nanostructures. The first nanostructure is chemically synthesized Au nanoparticles coated with ultra-thin shells (ca. one to ten atomic layers) of various transition metals, e.g., Pt, Pd, Ni and Co, respectively. Boosted by the long-range effect of the enhanced electromagnetic (EM) field generated by the highly SERS-active Au core, the originally low surface enhancement of the transition metal can be substantially improved giving total enhancement factors up to 104–105. It allows us to obtain the Raman spectra of surface water, having small Raman cross-section, on several transition metals for the first time. To expand the surface generality of SERS, tip-enhanced Raman spectroscopy (TERS) has been employed. With TERS, a nanogap can be formed controllably between an atomically flat metal surface and the tip with an optimized shape, within which the enhanced EM field from the tip can be coupled (borrowed) effectively. Therefore, one can obtain surface Raman signals (TERS signals) from adsorbed species at Au(110), Au(111) and, more importantly, Pt(110) surfaces. The enhancement factor achieved on these single crystal surfaces can be up to 106, especially with a very high spatial resolution down to about 14 nm. To fully accomplish the borrowing strategy from different nanostructures and to explain the experimental observations, a three-dimensional finite-difference time-domain method was used to calculate and evaluate the local EM field on the core–shell nanoparticle surfaces and the TERS tips. Finally, prospects and further developments of this valuable strategy are briefly discussed with emphasis on the emerging experimental methodologies.
Co-reporter:Bin Ren;Guo-Kun Liu;Xiao-Bing Lian
Analytical and Bioanalytical Chemistry 2007 Volume 388( Issue 1) pp:29-45
Publication Date(Web):2007 May
DOI:10.1007/s00216-007-1141-2
Surface-enhanced Raman spectroscopy (SERS) has developed into one of the most important tools in analytical and surface sciences since its discovery in the mid-1970s. Recent work on the SERS of transition metals concluded that transition metals, other than Cu, Ag, and Au, can also generate surface enhancement as high as 4 orders of magnitude. The present article gives an overview of recent progresses in the field of Raman spectroscopy on transition metals, including experimental, theory, and applications. Experimental considerations of how to optimize the experimental conditions and calculate the surface enhancement factor are discussed first, followed by a very brief introduction of preparation of SERS-active transition metal substrates, including massive transition metal surfaces, aluminum-supported transition metal electrodes, and pure transition metal nanoparticle assembled electrodes. The advantages of using SERS in investigating surface bonding and reaction are illustrated for the adsorption and reaction of benzene on Pt and Rh electrodes. The electromagnetic enhancement, mainly lightning-rod effect, plays an essential role in the SERS of transition metals, and that the charge-transfer effect is also operative in some specific metal–molecule systems. An outlook for the field of Raman spectroscopy of transition metals is given in the last section, including the preparation of well-ordered or well-defined nanostructures, and core-shell nanoparticles for investigating species with extremely weak SERS signals, as well as some new emerging techniques, including tip-enhanced Raman spectroscopy and an in situ measuring technique.
Co-reporter:Guo-kun Liu, Bin Ren, De-yin Wu, Jian-ming Lin, Ren-ao Gu, Zhong-qun Tian
Journal of Electroanalytical Chemistry 2006 Volume 594(Issue 2) pp:73-79
Publication Date(Web):1 September 2006
DOI:10.1016/j.jelechem.2006.04.013
By combining cyclic voltammetry (CV) and surface-enhanced Raman spectroscopy (SERS), the electrochemical behaviors of acetylene (C2H2) on a roughened Rh electrode in 0.1 M HClO4 solution were studied. On both roughened and smooth Rh surfaces, a clear loop in the cyclic voltammogram was observed in the negative potential region, indicating the formation of a new phase. However, only on the roughened Rh surface was the Raman signal of surface species observed. The resemblance of the detected signal to that of polyacetylene indicates the occurrence of polymerization of acetylene at potentials more negative than −0.3 V. The electropolymerization of acetylene is proceeded via an electrochemical radical addition assisted by hydrogen radical. A combined contribution of both the resonant Raman effect and especially surface-enhanced Raman effect may account for the observed signal.
Co-reporter:Bin Ren Dr.;Gennaro Picardi Dr.;Bruno Pettinger Dr.;Rolf Schuster Dr.;Gerhard Ertl Dr.
Angewandte Chemie 2005 Volume 117(Issue 1) pp:
Publication Date(Web):15 DEC 2004
DOI:10.1002/ange.200460656
Auf die Spitze getrieben: Durch spitzenverstärkte Raman-Spektroskopie (TERS) wurden Spektren von auf Pt- und Au-Einkristalloberflächen adsorbiertem Benzolthiol und Pyridin-4-thiol gemessen (siehe Bild). Die Benzolthiol-Spektren unterscheiden sich je nach Oberfläche deutlich, was das Potenzial von TERS als Diagnosewerkzeug mit hoher Auflösung für die Untersuchung von Grenzflächen anzeigt.
Co-reporter:Bin Ren Dr.;Gennaro Picardi Dr.;Bruno Pettinger Dr.;Rolf Schuster Dr.;Gerhard Ertl Dr.
Angewandte Chemie International Edition 2005 Volume 44(Issue 1) pp:
Publication Date(Web):15 DEC 2004
DOI:10.1002/anie.200460656
A tip for surface scientists: Tip-enhanced Raman spectroscopy (TERS) was used to record surface Raman spectra of benzenethiol and pyridine-4-thiol adsorbed on Au and Pt single-crystal surfaces (see picture). The benzenethiol spectra on the two surfaces are distinctly different. This result illustrates the power of TERS as a diagnostic tool with high spatial resolution for surface studies.
Co-reporter:Jia-Yi Huang, Cheng Zong, Li-Jia Xu, Yan Cui and Bin Ren
Chemical Communications 2011 - vol. 47(Issue 20) pp:NaN5740-5740
Publication Date(Web):2011/04/18
DOI:10.1039/C0CC05323F
Iodide adsorption and electrochemical negative potential desorption were proposed and compared to obtain clean SERS substrates. The two methods can effectively eliminate the interference of surface impurities in the SERS detection. SERS signals of membranes of living cells with a good reproducibility have been obtained.
Co-reporter:Zhong-Qun Tian, Bin Ren, Jian-Feng Li and Zhi-Lin Yang
Chemical Communications 2007(Issue 34) pp:NaN3534-3534
Publication Date(Web):2007/04/04
DOI:10.1039/B616986D
Surface-enhanced Raman scattering (SERS) was discovered three decades ago and has gone through a tortuous pathway to develop into a powerful diagnostic technique. Recently, the lack of substrate, surface and molecular generalities of SERS has been circumvented to a large extent by devising and utilizing various nanostructures by many groups including ours. This article aims to present our recent approaches of utilizing the borrowing SERS activity strategy mainly through constructing two types of nanostructures. The first nanostructure is chemically synthesized Au nanoparticles coated with ultra-thin shells (ca. one to ten atomic layers) of various transition metals, e.g., Pt, Pd, Ni and Co, respectively. Boosted by the long-range effect of the enhanced electromagnetic (EM) field generated by the highly SERS-active Au core, the originally low surface enhancement of the transition metal can be substantially improved giving total enhancement factors up to 104–105. It allows us to obtain the Raman spectra of surface water, having small Raman cross-section, on several transition metals for the first time. To expand the surface generality of SERS, tip-enhanced Raman spectroscopy (TERS) has been employed. With TERS, a nanogap can be formed controllably between an atomically flat metal surface and the tip with an optimized shape, within which the enhanced EM field from the tip can be coupled (borrowed) effectively. Therefore, one can obtain surface Raman signals (TERS signals) from adsorbed species at Au(110), Au(111) and, more importantly, Pt(110) surfaces. The enhancement factor achieved on these single crystal surfaces can be up to 106, especially with a very high spatial resolution down to about 14 nm. To fully accomplish the borrowing strategy from different nanostructures and to explain the experimental observations, a three-dimensional finite-difference time-domain method was used to calculate and evaluate the local EM field on the core–shell nanoparticle surfaces and the TERS tips. Finally, prospects and further developments of this valuable strategy are briefly discussed with emphasis on the emerging experimental methodologies.
Co-reporter:Yan Cui, Xiao-Shan Zheng, Bin Ren, Rui Wang, Jun Zhang, Ning-Shao Xia and Zhong-Qun Tian
Chemical Science (2010-Present) 2011 - vol. 2(Issue 8) pp:NaN1469-1469
Publication Date(Web):2011/06/23
DOI:10.1039/C1SC00242B
The increasing application of nanomaterials in biosensor and imaging sets a higher demand on the multifunctionalities of nanomaterials for obtaining multiple parameters of a same system under a same condition. In this work, multifunctional Au@organosilica nanoparticles with high stability were conveniently synthesized by direct hydrolyzing of 3-mercaptopropyltriethoxysilane in an aqueous solution in the presence of a Au core. Modification of the Au core with Raman reporters and the organosilica shell with fluorophore before and after the hydrolysis, respectively, produces multifunctional nanoparticles exhibiting Rayleigh scattering of the Au core, fluorescence signals of the fluorophores and surface-enhanced Raman scattering (SERS) of the Raman reporters. The nanoparticles can be used as multimodal tracers for living cell imaging and related biological research.
Co-reporter:De-Yin Wu, Jian-Feng Li, Bin Ren and Zhong-Qun Tian
Chemical Society Reviews 2008 - vol. 37(Issue 5) pp:NaN1041-1041
Publication Date(Web):2008/04/03
DOI:10.1039/B707872M
This tutorial review first describes the early history of SERS as the first SERS spectra were obtained from an electrochemical cell, which led to the discovery of the SERS effect in mid-1970s. Up to date, over 500 papers have been published on various aspects of SERS from electrochemical systems. We then highlight important features of electrochemical SERS (EC-SERS). There are two distinctively different properties of electric fields, the electromagnetic field and static electrochemical field, co-existing in electrochemical systems with various nanostructures. Both chemical and physical enhancements can be influenced to some extent by applying an electrode potential, which makes EC-SERS one of the most complicated systems in SERS. Great efforts have been made to comprehensively understand SERS and analyze EC-SERS spectra on the basis of the chemical and physical enhancement mechanisms in order to provide meaningful information for revealing the mechanisms of electrochemical adsorption and reaction. The EC-SERS experiments and applications are then discussed from preparation of nanostructured electrodes to investigation of SERS mechanisms and from characterization of adsorption configuration to elucidation of electrochemical reaction mechanisms. Finally, prospective developments of EC-SERS in substrates, methods and theory are discussed.
Co-reporter:Hai-Xin Lin, Jie-Ming Li, Bi-Ju Liu, De-Yu Liu, Jinxuan Liu, Andreas Terfort, Zhao-Xiong Xie, Zhong-Qun Tian and Bin Ren
Physical Chemistry Chemical Physics 2013 - vol. 15(Issue 12) pp:NaN4135-4135
Publication Date(Web):2013/01/16
DOI:10.1039/C3CP43857K
Surface-enhanced Raman spectroscopy (SERS) benefits from the enhanced electromagnetic field of the localized surface plasmon resonance effect of metallic (especially coinage metals) nanoparticles or nanostructures. The detection sensitivity and reproducibility of SERS measurement appear to be the two critical issues in SERS. To solve the problem associated with traditional nanoparticle aggregates and SERS substrates, we propose in this work single particle SERS. We prepared uniform gold microspheres with controllable size and surface roughness using an etching-assisted seed-mediated method. Single particle dark-field spectroscopy and SERS measurements show that particles with a larger roughness give a stronger SERS signal, but still retain a good reproducibility. This study points to the promising future of the practical application of the single particle SERS technique for trace analysis.
Co-reporter:Xiang Wang, Sheng-Chao Huang, Teng-Xiang Huang, Hai-Sheng Su, Jin-Hui Zhong, Zhi-Cong Zeng, Mao-Hua Li and Bin Ren
Chemical Society Reviews 2017 - vol. 46(Issue 13) pp:NaN4041-4041
Publication Date(Web):2017/06/07
DOI:10.1039/C7CS00206H
Surface and interfaces play key roles in heterogeneous catalysis, electrochemistry and photo(electro)chemistry. Tip-enhanced Raman spectroscopy (TERS) combines plasmon-enhanced Raman spectroscopy with scanning probe microscopy to simultaneously provide a chemical fingerprint and morphological information for the sample at the nanometer spatial resolution. It is an ideal tool for achieving an in-depth understanding of the surface and interfacial processes, so that the relationship between structure and chemical performance can be established. We begin with the background of surfaces and interfaces and TERS, followed by a detailed discussion on some issues in experimental TERS, including tip preparation and TERS instrument configuration. We then focus on the progress of TERS for studying the surfaces and interfaces under different conditions, from ambient, to UHV, solid–liquid and electrochemical environments, followed by a brief introduction to the current understanding of the unprecedented high spatial resolution and surface selection rules. We conclude by discussing the future challenges for TERS practical applications in surfaces and interfaces.
Co-reporter:Yi-Fan Huang, De-Yin Wu, Hong-Ping Zhu, Liu-Bin Zhao, Guo-Kun Liu, Bin Ren and Zhong-Qun Tian
Physical Chemistry Chemical Physics 2012 - vol. 14(Issue 24) pp:NaN8497-8497
Publication Date(Web):2012/05/22
DOI:10.1039/C2CP40558J
p-aminothiophenol (PATP) is an important molecule for surface-enhanced Raman spectroscopy (SERS). It can strongly interact with metallic SERS substrates and produce very strong SERS signals. It is a molecule that has often been used for mechanistic studies of the SERS mechanism as the photon-driven charge transfer (CT) mechanism is believed to be present for this molecule. Recently, a hot debate over the SERS behavior of PATP was triggered by our finding that PATP can be oxidatively transformed into 4,4′-dimercaptoazobenzene (DMAB), which gives a SERS spectra of so-called “b2 modes”. In this perspective, we will give a general overview of the SERS mechanism and the current status of SERS studies on PATP. We will then demonstrate with our experimental and theoretical evidence that it is DMAB which contributes to the characteristic SERS behavior in the SERS spectra of PATP and analyze some important experimental phenomena in the framework of the surface reaction instead of the contribution “b2 modes”. We will then point out the existing challenges of the present system. A clear understanding of the reaction mechanism for nitrobenzene or aromatic benzene will be important to not only understand the SERS mechanism but to also provide an economic way of producing azo dyes with a very high selectivity and conversion rate.
