Phase engineering Governing reaction pathways in Phosphorus-Doped copper oxide for selective CO2 electroreduction to CH4 and Multicarbon products

Copper-based catalysts exhibit moderate adsorption energy for *CO intermediates and have attracted significant attention for CO 2 electroreduction to fuels and high-value chemicals, but their low activity and poor selectivity remain challenges. Herein, we synthesized phosphorus-doped copper oxide (CuO x P y ) and demonstrated that phosphorus governs the phase transition, creating distinct interfaces that regulate proton donors or local OH – concentrations, thereby modulating the reaction pathway and directing CO 2 electroreduction selectively towards CH 4 or multi-carbon (C 2+ ) products. Notably, the P-Cu 2 O/Cu interface derived from amorphous CuO x P y exhibits a Faradaic efficiency (FE) for CH 4 of 53 % ± 4.99 % at a current density of 0.4 A cm −2 . In contrast, the Cu 2 P 2 O 7 /Cu 2 O interface obtained from crystalline CuO x P y achieves a FE C2+ of 74.3 % ± 1.75 % at 0.8 A cm −2 . Experiments and theoretical calculations reveal that the accumulation of proton donors at the P-Cu 2 O/Cu interface facilitates the protonation of the *CO intermediate, thereby enhancing CH 4 production. The Lewis acid sites of Cu 2+ at the Cu 2 P 2 O 7 /Cu 2 O interface enhance the local OH – concentration and lower the energy barrier for C-C coupling, resulting in high selectivity towards C 2+ products. This study presents a novel paradigm for the rational regulation of selectivity in CO 2 electroreduction products through modulation of the interfacial microenvironment.