Electrochemical fixation of CO2 over a Mo plate to prepare a Mo2C film for electrocatalytic hydrogen evolution

Abstract

Conversion of carbon dioxide into a hydrogen-evolution electrocatalyst is an ideal protocol to promote carbon neutrality by eliminating emissions of carbon dioxide and producing carbon-free hydrogen energy. Electrochemical fixation of carbon dioxide in molten salts by using a Mo-plate cathode and a Ni–Cr anode is herein demonstrated to produce a cathodic Mo₂C film and anodic oxygen. The molten salt electrochemical method offers an efficient modulation of thickness, adhesion and more importantly, interfacial confinement between the Mo₂C film and Mo. The resulting Mo₂C–Mo binder-free electrode hence shows enhanced electrocatalytic activity towards hydrogen evolution, as rationalized by the lower hydrogen adsorption energy at the Mo₂C–Mo interface. The electrochemical reduction of carbon dioxide over a metal substrate is therefore a generic method integrating fixation of carbon dioxide and surface carbonization of a metal to functional films.