Monitoring Surface Plasmon-driven Catalytic Reaction With SERS

Surface enhanced Raman scattering(SERS)is very popular in the field of detection and analysis due to its fast and simple sample requirements.Indeed,as a highly sensitive,non-marking technology,it has an irreplaceable role in monitoring interface properties and intermolecular interactions.Among them,the surface plasmon plays a key role,which can collect a large amount of electromagnetic energy through local surface plasmon resonance(LSPR)to overcome the energy barrier of the reaction molecule and promote the catalytic reaction.Specifically,the plasmon decay will generate a large number of hot electrons,providing a large amount of kinetic energy to perform the reduction reaction,and the holes appearing in pairs with the electrons are used to complete a large number of oxidation reactions.Based on this,we explored new types of surface plasmon catalytic reaction under the monitoring of SERS technology,which made the reaction system expand.(1)Large amount researched aromatic compounds with mercapto groups such as p-aminothiophenol(PATP)and p-nitrothiophenol(PNTP)are mainly based on the stable chemical bond formed between sulfur and precious metals.So these compounds have been extensively studied for surface plasmon catalytic reactions.Based on this,we consider whether there are other groups that can be connected to the noble metal and still be able to carry out the catalytic reaction.Under the monitoring of SERS,we explored whether the molecule of p-iodoaniline(PIAN)can be strengthened.As a result,it was found that this probe molecule had the surface plasmon catalytic reaction under the irradiation of laser.What's more,we regulated the isomerization of p,p'-diiodoazobenzene(DIAB)by concentration and expanded its application.(2)In SERS studies,Raman enhancement is usually judged by the formation of azo compounds with nitrogen-nitrogen double bonds.Based on this,we exploreda new type of reaction molecule and found that it can undergo efficient catalytic reaction.The structure of 4,4'-dithiodibenzoic acid(DTBA)is equivalent to that of two p-mercaptobenzoic acid(4-MBA)molecules that lose hydrogen ions and are connected together.It is this bimolecular mechanism of DTBA that promotes efficient ionization reactions.Under the irradiation of laser light,DTBA molecules are broken to form bimolecules similar to 4-MBA,which are adsorbed to the surface of Ag NPs.This kind of bimolecular coupling greatly improves the probability of binding with Ag NPs,making the ionization reaction stable and efficient.By comparing DTBA and 4-MBA molecules in parallel experiments,it is clear that DTBA molecules have better Raman activity,higher reaction efficiency and more stable reactions.And we have also explored that this molecule has the carboxylic acid group,which has a certain sensitivity to pH.Through the systematic study of this subject,we extended the surface plasmon-driven catalytic reaction system with the help of SERS.Moreover,it provides a certain reference value for the application of azobenzene isomerization,pH sensor and intracellular pH monitoring.