Accurate SERS Monitoring Of The Plasmon Mediated Photocatalytic Process Involving Carbon Dots/Metal Composite

Surface plasmons（SPs）catalyst（coinage metals such as gold,silver and copper,etc.）is a new kind of photocatalyst.Based on its unique nanostructure,when SPs are resonantly excited（SPR）,the collective oscillation of conduction electrons in nanostructured metals can redistribute not only the electromagnetic fields but also the hot excited carriers.On the other hand,the interaction between hot electron and phonon will lead to the increase of lattice temperature based on photothermal effect,which will eventually afford photon,electron and heat energy redistribution over time and space.When the plasmon-mediated chemical reaction（PMCR）takes place,the enhanced electromagnetic field from the metal plasmonic structures will amplify the relevant spectral information of the molecules,such as plasmon-enhanced Raman,infrared and fluorescence spectroscopies.Among those spectroscopic techniques,surface enhanced Raman spectroscopy（SERS）is the most influential tool used to reveal the spectral information of species on the surface or interface of a substrate with super sensitivity at a molecular level.Recent years,carbon dots（CDs）have attracted more and more attention due to its unique photoinduced electron transfer properties,excellent photoelectric conversion ability,good biocompatibility and easy surface modification.Many synergies can be achieved by combining CDs with other types of materials.In this paper,CDs with the excellent electron donor/receptor nature and abundant surface functional groups was combined with SPs nanostructures,constructing the CDs/metal composite nanomaterials,which expended the surface plasmon resonance（SPR）absorption,and acquired synergistic properties of two parts of materials:the excellent SERS property and enhance the catalytic properties under full spectrum of sunlight.And SERS method was applied to explore related photocatalytic process and mechanism,the main research contents are as follows:（1）Accurate SERS monitoring of the plasmon mediated UV/visible/NIR photocatalytic and photothermal catalytic process involving Ag@carbon dots.The excited carriers（electrons and holes）and heat energy that originate from plasmonic metal nanomaterials are crucial to the enhancement of the photocatalytic performance.In this study,an Ag@carbon dots（Ag@CDs）hybrid has been prepared with excellent Fenton-like photocatalytic and photothermal conversion properties for catalyzing H₂O₂to generate hydroxyl radicals（˙OH）for the degradation of crystal violet（CV）dye under full solar spectrum irradiation based on a unique plasmon effect.We have obtained some intrinsic kinetics information,including the reaction rate and apparent activation energy on the surface of the Ag@CDs,through a surface-enhanced Raman scattering strategy to investigate the contributions made by photocatalytic and photothermal effects in the plasmon mediated reaction under irradiation from ultraviolet（UV）/visible/near-infrared（NIR）light.This work provides deep insights into understanding the plasmon-mediated photocatalytic mechanism of the Ag@CDs hybrid.（2）SERS monitoring of enzyme-like reaction by Au@carbon dots and their photoinduced enhanced catalytic oxidation effect.Based on the explanation of PMCR mechanism under near-infrared light irradiation in the previous part of work,the reason why SPs enhances photochemical reaction is mainly photothermal effect based on electron-phonon interaction.In this work,we successfully synthesis Au@carbon dots（Au@CDs）hybrid material,expanding the SPR absorption of Au to the near infrared region.We emphatically studied the excellent photo-thermal conversion ability and the photoinduced enhanced peroxidase-like/glutathione oxidases-like activity of Au@CDs under near infrared laser irradiation.This paper provides theoretical support for the potential application of this material in the synergistic photodynamic/photothermal treatment of tumors and SERS monitoring of tumor microenvironment.