PNNL

Abstract

Bimetallic nanostructures support a large spectrum of chemical reactions. When comprised of a mixture of nobel and catalytic metals, bimetallic structures can drive light-driven chemical transformations. The yields and selectivities of reactions performed using these catalysts directly depend on their makeup, which often varies on the nanometer scale. Herein, we use tip-enhanced Raman spectroscopy (TERS) to investigate the plasmonic and photocatalytic properties of walled gold-palladium microplates (WAu@PdMPs) and their monometallic counterparts with nanometer spatial resolution, chemical selectivity, and high sensitivity. We find that 4-nitrobenzenethiol (4-NBT) can be transformed into both to p,p'-dimercaptoazobisbenzene (DMAB) and 4-aminothiophenol (4-ATP) on WAu@PdMPs. In contrast, monometallic AuMPs and WAuMPs exclusively yield DMAB, formed as a result of photocatalytic reduction of 4-NBT. Using 4-NBT as a molecular reporter, we find that the efficiencies of these catalytic reactions strongly depend on the nano-structural makeup of the microplates.