Determination of reactivity on electrochemical catalysts via interface engineering

Abstract

Electrocatalysis, whose reaction venue locates at the catalyst–electrolyte interface, is controlled by the electron transfer across the electric double layer (EDL), envisaging a mechanistic link between the electron transfer rate and the EDL structure. To precisely control EDL structure, there are two points for engineering: electrolyte engineering and electrode engineering. A fine example of electrolyte engineering is in the CO2 reduction reaction, of which rate shows a strong dependence on the alkali metal cation (M+) identity, but there is yet to be a unified molecular picture for that. Using quantum-mechanics-based atom-scale simulation, we herein scrutinize the M+- coupling capability to possible intermediates, and establish H+- and M+-associated ET mechanisms for CH4 and CO/C2H4 formations, respectively. These theoretical scenarios are successfully underpinned by Nernstian shifts of polarization curves with the H+ or M+ concentrations and the first-order kinetics of CO/C2H4 formation on the electrode surface charge density. Another strategy, electrode engineering, is a change in the potential of zero charge (EPZC), an intrinsic property of electrode material and able to touch EDL structure. Endowing oxygen functional groups on transition metal single-atom catalysts, i.e., CoNC, we change the EPZC of CoNC, consequently modifying surface charge density which modulates oxygen reduction reaction activity, and selectivity towards H2O2.