Preparation,Modification And Application Of Single Gold And Silver Nanoelectrodes

Nanoelectrodes have attracted much attention due to their small overall size,high mass transfer rate,and fast electrochemical response.They have been applied in different fields such as fundamental electrochemical research,neurobiology and single cell sensing,scanning electrochemical microscopy(SECM)and single nanoparticle detection.In this paper,single gold and silver nanoelectrodes were prepared by laser-assisted pulling technique and the following studies were mainly carried out:1.A new signal amplification strategy has been presented to fabricate nanoprobe.This assay is approached through the electrodeposition of Prussian Blue(PB)onto single gold nanopore electrode(SAuNPE)and then overcoating of the PB modified SAuNPE with a thin membrane of polypyrrole(PPy)and carbon dots(CDs).The nanoprobe was employed to detect hydrazine with high sensitivity and good stability.This nanoprobe has the advantages of small overall dimension,fast electrochemical response and good signal amplification ability,which provides some new ideas for constructing functional electrochemical nanoprobes.2.A new strategy was developed to investigate the oxidation of Ag NPs at the single particle level and aggregation state by using single Au nanoelectrode/ultramicroelectrode.The results showed that the ASV peak potentials,either for single Ag NPs or aggregated Ag NPs,were shifted positively with the increase of Ag NPs diameters,but the peak shapes were different from single Ag NPs to the aggregation state.Moreover,the SEM,TEM,DLS and UV-vis spectra data showed excellent correlation with electrochemical results.We think these interesting results can help us deeply understand the metal NPs oxidation process and will benefit the related applications.3.Gold nanoparticles(Au NPs)were modified onto single silver nanowire electrode by metal displacement reaction to construct single Au @ Ag nanowire electrode.The bimetallic nanowires were used to monitor 4-nitrothiophenol / p-mercaptoazobenzene(4-NTP / DMAB)and 4-nitrothiophenol / 4-aminothiophenol(4-NTP / 4-ATP)reduction process by surface enhanced Raman spectroscopy(SERS).The results show that single Au @ Ag nanowire exhibits both good SERS activity and excellent catalytic performance.This work enabling the research of SERS performance at the single nanowire level,which is conducive to expanding the application of SERS in the field of hybrid metal-metal nanostructure catalysis.