Electrocatalytic activity of gold and gold-based bimetallic nanoparticles derived from their surface topography

Abstract

The electrochemical activity of Au nanoparticles (NPs) with varied sizes and shapes was decomposed into the components of defective {111}, {110} and {100} facets on their surfaces based on the deconvolution of cyclic voltammetry data and with the aid of density functional theory calculation. It revealed an overwhelmingly large negative shift in the electrode potential induced by defective {111} facets with respect to the electrode potential of bulk gold, a relatively large positive shift induced by defective {100} facets, and a fairly small negative shift induced by defective {110} facets. This counter-intuitive surface facet-differentiated impact on the electrode potential of Au NPs evolved into high reducing activity with the surface fractions of defective {111} facets increasing, which was dominantly hinged on the NP surface topographic features; these accounted for the fact that 70 nm trisoctahedral and 3 nm quasi-spherical Au NPs exhibited nearly identical anti-galvanic reaction and oxygen reduction reaction activities. Moreover, the surface topography-induced electrocatalytic activity of Au NPs with varied sizes and shapes is demonstrated by utilizing them as electrocatalysts for the oxygen reduction reaction (ORR). Furthermore, the as-prepared Au@Pd NPs by the simple anti-galvanic reaction (AGR) exhibit a better ORR performance in alkaline media (46 mV higher than commercial Pt/C catalysts). Our primary results provide humble steps toward the full understanding of the impact of surface topography on the electrode potentials of nanoscale materials.