Spatiotemporal active phase evolution for CO2 electrocatalysis

Abstract

Revealing and redirecting the dynamic evolution of active species in efficient electrochemical CO2 reduction (ECR) catalysts is challenging. By observing the chemical and morphological evolution in highly efficient ECR catalysts at the nanoscale via operando soft X-ray microscopy, we identified the dynamic transformation of cationic Cu species during operation. The surface Cu2+ phases, observed during a dynamic phase transformation of Cu(OH)2, additionally boost C？C coupling activity beyond the capability of metallic Cu phases. We suggest that copper(II)-carbonate-hydroxide species could dynamically persist under a cathodic environment. By observing the Cu+ phase during the phase transformation and the formation of surface Cu2+ species, we were able to electrochemically redirect low-active catalysts into high-active catalysts for C？C coupling. Density functional theory calculations also support that Cu2+ species could contribute to C？C coupling activity enhancement via ？CO adsorption energy modulation.