Exploration of surface plasmon-assisted catalysis (SPAC) as a new route for heterogeneous catalysis

Abstract

Plasmonics is the study of the interactions between the free electrons of a metal, and the electric field component of light. In the presence of the oscillating electronic field, the free electrons in the metal oscillate collectively, resulting in a localized surface plasmon resonance (LSPR). This LSPR is the reason for the enhanced spectra of surface enhanced Raman spectroscopy (SERS) compared to Raman spectroscopy. A commonly used Raman reporter is 4-aminothiophenol (4-ATP), which has been well studied. 4-ATP is known to undergo a surface catalytic coupling reaction to produce an aromatic azo species: 4,4’-dimercaptoazobenzene (4,4’-DMAB). This work explores the generality of the surface plasmon-assisted catalysis (SPAC) by studying the constitutional isomers, the 2- and 3- constituents of 4-ATP. The reusability of the catalyst (electrode set-up) is also tested to suggest a new route for heterogeneous catalysis, and further tested if the oxidative product, 4,4’-DMAB, could be obtained once removed.