Surface plasmon assisted catalysis (SPAC) reactions of 4-aminothiophenol (4ATP) to and back from 4,4′-dimercaptoazobenzene (DMAB) have been investigated by single particle surface enhanced Raman spectroscopy, using a self-designed gas flow cell to control the reductive/oxidative environment over the reactions. Conversion of 4ATP into DMAB is induced by energy transfer (plasmonic heating) from surface plasmon resonance to 4ATP, where O2 (as an electron acceptor) is essential and H2O (as a base) can accelerate the reaction. In contrast, hot electron (from surface plasmon decay) induction drives the reverse reaction of DMAB to 4ATP, where H2O (or H2) acts as the hydrogen source. More interestingly, the cyclic redox between 4ATP and DMAB by SPAC approach has been demonstrated. This SPAC methodology presents a unique platform for studying chemical reactions that are not possible under standard synthetic conditions.

Plasmon-driven chemical reaction of p-nitrothiophenol (pNTP) dimerizing into p,p'-dimercaptoazobenzene (DMAB) has been monitored using single particle surface enhanced Raman spectroscopy, which provides laser wavelength- and power-dependent conversion rates of the reaction.

Tuning CO 2 hydrogenation selectivity to obtain targeted value-added chemicals and fuels has attracted increasing attention. However,af undamental understanding of the way to control the selectivity is still lacking, posing achallenge in catalyst design and development. Herein, we report our new discovery in ambient pressure CO 2 hydrogenation reaction where selectivity can be completely reversed by simply changing the crystal phases of TiO 2 support (anatase-or rutile-TiO 2) or changing metal loadings on anatase-TiO 2 .O perando spectroscopyand NAP-XPS studies reveal that the determining factor is adifferent electron transfer from metal to the support, most probably as ar esult of the different extents of hydrogen spillover,w hichc hanges the adsorption and activation of the intermediate of CO.Based on this new finding,wecan not only regulate CO 2 hydrogenation selectivity but also tune catalytic performance in other important reactions,t hus opening up ad oor for efficient catalyst development by rational design.

Graphene continues to attract tremendous interest, owing to its excellent optical and electronic properties. On the basis of its unique features, graphene has been employed in the ever-expanding research fields. Surface-enhanced Raman scattering (SERS) may be one of the significant applied fields where graphene can make a difference. Since its discovery, SERS technique has been capable of ultra sensitively detecting chemical and biological molecules at very low concentration, even at single molecule level, but some problems, such as irreproducible SERS signals, should be overcome before practical application on spectra analysis. Graphene can be a promising candidate to make up the deficiency of conventional metal SERS substrate. Furthermore, graphene, serving as the enhancement material, is usually deemed as a chemically inert substance to isolate the interactions between metal and probe molecules. While, irradiated by laser, structure changes of graphene under specific conditions and the contributions of its high electron mobility in plasmoninduced catalytic reactions are often ignored. In this review, we mainly focus on the state-of-the-art applications of graphene in the fields of SERS and laser-induced catalytic reactions. The advances of informative Raman spectra of graphene are firstly reviewed. Then, the graphene related SERS substrates, including graphene-enhanced Raman scattering (GERS) and graphene-mediated SERS (G-SERS), are summarized. We finally highlight the catalytic reactions occurring on graphene itself and molecules adsorbed onto graphene upon laser irradiation.In this review, we mainly focus on the state-of-the-art applications of graphene in the fields of Surfaceenhanced Raman scattering (SERS) and plasmon-induced catalytic reactions. The advances of informative Raman spectra of graphene are firstly reviewed. Then, the graphene related SERS substrates, including graphene-enhanced Raman scattering (GERS) and graphene-mediated SERS (G-SERS), are summarized. We finally highlight the catalytic reactions occurring on graphene itself and molecules adsorbed onto graphene upon laser irradiation.

Synthesis of Fe3O4/polyaniline (PANI) core/shell hybrid microspheres through an in situ polymerization route with the 300 nm Fe3O4 microspheres as the cores and nucleation sites for PANI is reported. PANI shell thickness, from 30 nm to 120 nm, can be controlled by modulating the weight ratio of aniline monomer and Fe3O4 microspheres. Fe3O4 microspheres that are actually comprised of many small nanoparticles display super paramagnetic feature, which has been maintained in Fe3O4/PANI core/shell hybrid materials. Fe3O4/PANI core/shell hybrid materials have enhanced microwave absorption than both the Fe3O4 microspheres and PANI, where a maximum reflection loss of −37.4 dB at 15.4 GHz has been reached from the sample with a PANI shell thickness of 100 nm. Introduction of dielectric loss, interfacial loss, and improved impedance from coating the Fe3O4 microspheres with PANI should account for the improved microwave absorption properties of the prepared Fe3O4/PANI core/shell hybrid materials. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1909–1916, 2013

Here, we demonstrate a facile synthesis of homogeneous Ag nanostructures fully covering the polyaniline (PANI) membrane surface simply by introducing organic acid in the AgNO(3) reaction solution, as an improved technique to fabricate well-defined Ag nanostructures on PANI substrates through a direct chemical deposition method [Langmuir2010, 26, 8882]. It is found that the chemical nature of the acid is crucial to create a homogeneous nucleation environment for Ag growth, where, in this case, homogeneous Ag nanostructures that are assembled by Ag nanosheets are produced with the assistance of succinic acid and lactic acid, but only scattered Ag particles with camphorsulfonic acid. Improved surface wettability of PANI membranes after acid doping may also account for the higher surface coverage of Ag nanostructures. The Ag nanostructures fully covering the PANI surface are extremely sensitive in the detection of a target analyte, 4-mercaptobenzoic acid (4-MBA), using surface-enhanced Raman spectroscopy (SERS), with a detection limit of 10(-12) M. We believe the facilely fabricated SERS-active substrates based on conducting polymer-mediated growth of Ag nanostructures can be promising in the trace detection of chemical and biological molecules.

We demonstrate the plasmon‐driven catalytic reactions of 4‐nitrothiophenol (4NTP) on a single Ag microsphere by an in situ surface‐enhanced Raman spectroscopy (SERS) technique. The highly SERS‐active hierarchical Ag structures served as an ideal platform to study plasmon‐driven catalytic reactions. This single‐particle surface‐enhanced Raman spectroscopy (SP‐SERS) technique coupled with inbuilt apparatus allow us to study the impact of reaction atmospheres and laser power on the rate of dimerization and reduction of 4NTP. Contrary to that found in previous studies, 4NTP could be transformed into 4‐aminothiophenol under H2O or H2 atmosphere. The broadening and splitting of the ν(CC) band during the reaction results from the frequency shift of the ν(CC) band that arises from different products. Our results suggest that the SP‐SERS technique is ideally suited to study plasmon‐driven catalytic reactions because of the possibility to monitor the reaction under controlled atmospheres in real time.

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