Dual regulation of geometry and water activation over coherent interface-rich inverse CeO2/CuO catalysts enabling highly selective CO2 electroreduction from C2H4 to CH4

Developing efficient electrocatalysts capable of achieving effective electrochemical CO 2 -to-CH 4 conversion over a broad potential window remains a significant challenge in the field. Herein, we present a facile strategy for the synthesis of inverse CeO 2 /CuO catalysts through a hydrothermal approach, wherein CeO 2 nanodomains are supported on the surface of CuO. This catalyst exhibits exceptionally high CH 4 selectivity across the investigated voltage range, with a peak Faradaic efficiency of 63.6% and a corresponding partial current density of −472.9 mA cm −2 at −1.6 V vs. RHE, while the pure CuO catalyst without CeO 2 component was found to be active for electroreducing CO 2 to C 2+ products (C 2 H 4 ), as the adjacent Cu sites were beneficial for adsorbing multiple *CO intermediates and subsequent C C coupling. The incorporation of CeO 2 into Cu 1 Ce 9 -O x exerts a dual regulatory effect, synergistically suppressing C C coupling by reducing *CO coverage and optimizing *CO protonation kinetics for enhanced CH 4 selectivity. The presence of CeO 2 not only blocks the active sites of CuO for CO 2 -to-*CO intermediate conversion (thus lowering *CO coverage) but also facilitates water dissociation to generate abundant *H species, which subsequently migrate to Cu sites in Cu 1 Ce 9 -O x catalyst through the coherent interface between CuO and CeO 2 . These *H species subsequently facilitate the hydrogenation of *CO intermediates, ultimately resulting in CH 4 formation. Density functional theory (DFT) calculations demonstrate that CuCe-O x catalyst with strong H 2 O dissociation capability decreases the energy barrier for *CHO formation and favors *CO → *CHO conversion, thereby promoting CO 2 RR-to-CH 4 conversion. This work provides an effective strategy to enhance *H generation and the hydrogenation of *CO intermediates, thereby offering a feasible approach to improve CH 4 production efficiency in electrochemical CO 2 conversion. Compared with pristine CuO, CeO 2 nanodomains anchored on CuO surfaces redirect CO 2 electroreduction selectivity from C 2 H 4 to CH 4 . The presence of CeO 2 not only modulate *CO intermediate coverage but also accelerate H 2 O dissociation to produce abundant *H species, thereby promoting *CO protonation and boosting CH 4 formation with enhanced Faradaic efficiency. Download: Download high-res image (170KB) Download: Download full-size image