Electroreduction of CO2 to CO over wide potential window by in situ electrodeposited CdCO3/Cd-CP electrocatalysts

Abstract

The design of robust electrocatalysts for CO₂ electroreduction with large current density and high selectivity for the desired production is a crucial step in realizing a carbon-neutral energy cycle and producing more valuable chemicals and fuels. Herein, the CdCO₃/Cd nanostructure was in situ electrodeposited on a carbon paper (CP) substrate to fabricate CdCO₃/Cd-CP-x (where x represents the concentration of Cd(NO₃)₂·4H₂O) electrocatalysts that can boost the electrocatalytic performance of CO₂ electroreduction. When CdCO₃/Cd-CP-2 was applied as an electrocatalyst, the faradaic efficiency (FE) of CO production remained above 90% over a wide potential window, and the current density reached up to 203 mA cm⁻² at −2.4 V vs. Ag/Ag⁺. The enhanced CO₂ electroreduction was mainly attributed to the intrinsic properties of the CdCO₃/Cd nanostructure with abundant active sites, the introduction of CdCO₃, and tight contact with the CP substrate. Density functional theory calculations illustrated that the CdCO₃ in the electrocatalyst promoted the formation of the *COOH intermediate, and the synergistic effect between the CdCO₃ and the Cd support decreased the adsorption ability for the *CO intermediate, which improved the CO production rate. Furthermore, the CdCO₃/Cd-CP-8 electrocatalyst also exhibited highly selective CO production ability at low CO₂ concentration with outstanding CO₂ conversion rate (34%), which offers a chance to achieve the requirements of practical applications.