Controlling Plasmon-Aided Reduction of p-Nitrothiophenol by Tuning the Illumination Wavelength

Plasmon-mediated chemical reactions (PMCRs) possess desirable opportunities for manipulating the reaction outcomes due to the unique impact from surface plasmons. However, achieving PMCR product selectivity by tuning the light wavelength has rarely been demonstrated and the underlying mechanism of product selectivity remains elusive. This work studies the reaction mechanism of one classical type of PMCR, plasmon-aided reduction of p-nitrothiophenol (PNTP), and discovers that the reduction product of PNTP can be easily manipulated by adjusting the excitation light wavelength due to the different thermal and hot-electron effects induced by the different wavelengths. Specifically, the sole product of p,p′-dimercaptoazobenzene is obtained under 514 nm light due to the dominant thermal effect thus created, whereas p-aminothiophenol is more favorably produced under 785 nm light, which enables more efficient generation of hot electrons.