Isolating and stabilizing active copper species in layered double hydroxide to enhance electrocatalytic CO2 reduction to CH4

Abstract

Electrocatalytic CO₂ reduction reaction (CO₂RR) to CH₄ presents an effective solution to environmental and energy challenges. Catalysts featuring monodispersed Cu sites can suppress the dimerization of *CO intermediate, which makes them promising candidates for achieving high selectivity in the deep reduction of CO₂ to CH₄. However, most Cu-based catalysts inevitably undergo restructuring during the reaction, which can alter the CO₂ reduction pathway and result in decreased performance. In this study, a series of Cu-based layered double hydroxides (LDHs) with stable monodispersed Cu sites were developed via atom isolation strategy. Among them, the CuMgAl-LDH catalyst with the monodispersed Cu sites achieved a Faradaic efficiency (FE) of 58.9 % for CO₂ reduction to CH₄ at a current density of 300 mA cm⁻² in a flow cell. In contrast, the CuAl-LDH catalyst without Mg doping showed a FE of 40.5 % for CO₂ reduction to C₂H₄. The results indicate that Mg atoms can inhibit the reconstruction process of CuMgAl-LDH during working conditions, preventing the aggregation of Cu atoms, thereby maintaining a high dispersion of Cu atoms. Additionally, a pulse electrolysis regulation strategy was employed to further enhance the selectivity and stability of CuMgAl-LDH, achieving a FE of 71.6 % for CO₂ reduction to CH₄, with stability maintained for over 13 h. The results present a useful case for studying catalyst reconstruction and improving CO₂ reduction performance.