Preserving Cu⁺ Active Sites through Intensified Electron Density for Sustained CO₂ Electroreduction

In the realm of CO 2 electroreduction to C 2 fuels and feedstocks, copper-based oxides (CuO x ) stand out for their exceptional ability to adsorb *CO intermediates. A significant challenge in the use of Cu-based oxide catalysts is the electroreduction-driven transformation of Cu + species to metallic Cu, predominantly attributed to the direct electron-mediated disruption of Cu–O bonds. Addressing this, our study introduces an approach that enhances the electron density in Cu 2 O through the integration of MoS 2, thereby stabilizing the Cu + species. This method mitigates the Cu–O bond attack by dispersing the excess electrons, which originate from the external electrode, within the Cu 2 O. Our composite material, Cu 2 O-MoS 2, demonstrates a 1.9-fold increase in Faraday efficiency for C 2 H 4 production (FE C2H4 ), achieving 23.3% at −1.3 V vs RHE, and exhibits predominant Cu + stability compared to pure Cu 2 O. Both experimental and computational analyses reveal that the lower work function (WF) of MoS 2, relative to Cu 2 O, facilitates electron transfer from MoS 2 to Cu 2 O, consequently augmenting the electron density in Cu 2 O. This increased electron density provides a protective barrier against electron attacks from the external electrode on the Cu–O bond. Our findings present a strategy for enhancing Cu + stability, thereby promoting C 2 H 4 production. Furthermore, this research contributes a different insight into the design of selective and stable catalysts for CO 2 reduction.