Application Of Nanoparticles Modified Fiber Probes For Plasmonic Catalysis Reactions

The localized surface plasmon resonance(LSPR)effect of metal nanostructures can enhance the photochemical reactivity and achieve conversion of materials and energy effectively,which has attracted more and more attention in recent years.However,the photochemical conversion efficiency of light in plasmonic catalysis reaction is still far lower than that of semiconductor catalysts in photocatalytic reaction.The problem of how to increase the utilization of light remains to be solved and the further study of mechanisms of the plasmonic catalysis reaction is needed.Therefore,it is essential to provide more detection means of plasmonic catalysis reaction in situ for studying reactions and mechanisms.In this article,nanoparticles modified fiber probes were used for the plasmon catalysis of nanoscale selective reaction of plasmonic catalysis.The main contents of this article included four parts.First,we developed the nanoparticles modified fiber probes.Second,the fiber probes were used for plasmonic catalysis reactions and SERS detection.Third,it was used in near-field scanning microscopy.At last,it was the application of nanoparticle composites modified fiber probes in plasmonic catalysis reaction.The details are as follows:1.A localized surface plasmon resonance(LSPR)fiber probe modified by Ag nanoparticles(Ag NPs)has been developed.The LSPR fiber probe could not only serve as a.substrate of plasmonic catalysis reaction but also detect signals ofsurface-enhanced Raman spectroscopy(SERS)of the reaction product in situ,which achieves the integration of the reaction and detection.Choosing p-Aminothiophenol(PATP)as a model molecule,by regulating the self-assembly time of Ag NPs,a uniform distributed monolayer structure can be formed with the excellent effect of the plasmonic catalysis and SERS signals collection;It was found that the SERS signal of the reaction product obtained from the internal excitation was 12.8 times of that from the external excitation under the same laser intensity conditions,demonstrating that the internal excitation method has advantages in the plasmonic catalysis and signal detection.The fiber probe can be used to quantify the concentrations of PATP solution during the range of 10-4 M-10-8 M.Using the LSPR fiber probe,we realized the in situ kinetics study of PATP coupling reaction.The LSPR fiber probe with the advantages of high sensitivity,low cost and facile preparation can be applied to in situ detection in a flexible manner with less damage to the sample.2.Combined with the shear force feedback mode of the scanning near-field optical microscope(SNOM),the LSPR fiber probe was applied to the morphologic imaging of the sample surface.The factors affecting the spatial resolution and signal detection of the LSPR fiber probe as surface microprobe are discussed.It is also feasible to combine the fiber probe with near-field scanning optical microscopy to carry out simultaneously the plasmonic catalysis reactions and detection on micro domains of the surface,and acquire a two-dimensional distribution of the assessment of surface reaction.3.The TiO2-Ag composites were selected as a system for fiber probes for the preliminary exploration of plasmonic catalysis reaction.The shuttle anatase TiO2 nanoparticles were synthesized by hydrothermal method,and Ag nanoparticles were loaded on them to prepare TiO2/Ag composites and TiO2@Ag nanoparticles.Scanning Electron Microscope(SEM),Transmission Electron Microscope(TEM),X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD),Photoluminescence(PL),Time-Resolved Photoluminescence(TRPL),Raman spectroscopy were used to characterize the performance of the TiO2-Ag composites.The characterization and mechanism analysis of the two kinds of composites showed that the loading of Ag increased the photoelectron-hole pair separation and photocatalytic efficiency of TiO2 nanoparticles.Moreover,the TiO2@Ag nanoparticles are superior to TiO2/Ag composites in inhibiting the recombination of photoelectron-hole pairs and plasmonic catalysis reaction.