Efficient Electrocatalytic Reduction of CO2 to Ethanol Enhanced by Spacing Effect of Cu?Cu in Cu2-xSe Nanosheets

It is highly desired yet challenging to strategically steer carbon dioxide (CO₂) electroreduction reaction (CO₂ER) toward ethanol (EtOH) with high activity, which provides a promising way for intermittent renewable energy reservation. Controlling spatial distance between the adjoining active centers and promoting the C C coupling progress are crucial to realize this purpose. Herein, ultrathin 2D Cu_2-xSe is prepared with abundant Se vacancies, where the spatial distance between the Cu Cu around the Se vacancies is effectively shortened because of the lattice stress. Besides, the moderate spatial distance induced by Se vacancies can significantly decrease the Gibbs free energy of asymmetric *CO *CHO coupling progress, effectively change the local charge distribution, decrease the valence state of Cu atoms and increase the electron-donating capacity of the dual active sites. Combining experimental observations and density functional theory   simulations, the Cu Cu dual sites with spatial distance of 2.51 Å in V_Se-Cu_2-xSe sample can catalyze CO₂ER to EtOH with high selectivity in a potential range from −0.4 to −1.6 V, and reach the highest faradaic efficiency of 68.1% at −0.8 V. This work reveals the influence of spacing effect on ethanol selectivity, and provides a new idea for future design of catalysts with chain elongation reaction, which can bring extensive attention.     

Regulating the Metallic Cu–Ga Bond by S Vacancy for Improved Photocatalytic CO2 Reduction to C2H4

Artificial photosynthesis, which converts carbon dioxide into hydrocarbon fuels, is a promising strategy to overcome both global warming and energy crisis. Herein, the geometric position of Cu and Ga on ultra-thin CuGaS₂/Ga₂S₃ is oriented via a sulfur defect engineering, and the unprecedented C₂H₄ yield selectivity is ≈93.87% and yield is ≈335.67 µmol g⁻¹ h⁻¹. A highly delocalized electron distribution intensity induced by S vacancy indicates that Cu and Ga adjacent to S vacancy form Cu–Ga metallic bond, which accelerates the photocatalytic reduction of CO₂ to C₂H₄. The stability of the crucial intermediates (*CHOHCO) is attributed to the upshift of the d-band center of ultra-thin CGS/GS. The C–C coupling barrier is intrinsically reduced by the dominant exposed Cu atoms on the 2D ultra-thin CuGaS₂/Ga₂S₃ in the process of photocatalytic CO₂ reduction, which captures *CO molecules effectively. This study proposes a new strategy to design photocatalyst through defect engineering to adjust the selectivity of photocatalytic CO₂ reduction.