Self-supported cube-like Cu nanoparticles with in-situ growth for efficient CO2 electroreduction to hydrocarbons

The electrochemical conversion of CO₂ into gaseous hydrocarbon fuels (CH₄ and C₂H₄) has become a prominent research focus, relying heavily on high-performance catalysts. In this study, commercial pure Cu foil was etched with FeCl₃, utilizing a simple etching approach to alter the etching time (30 s, 60 s, 90 s, and 120 s) to reconstruct the Cu foil surface and form active centers such as grooves and cube-like Cu nanoparticles. The hydrogenation of the *CO intermediate and C–C coupling were facilitated by these features, thereby promoting the formation of gaseous hydrocarbon products during CO₂ electroreduction. By varying the etching time, the groove morphology and the size, surface area, and roughness of the cube-like Cu nanoparticles were systematically tuned. The Cu foil electrode etched for 60 s exhibited the highest surface area and roughness, together with cube-like Cu nanoparticles of approximately ∼43.89 nm, thereby providing optimal active sites for *CO adsorption and selective hydrocarbon formation. At −1.2 V versus RHE, a total hydrocarbon Faradaic efficiency (FE) of 64.94% was achieved, including 33.34% for CH₄ and 31.60% for C₂H₄. These results demonstrate an effective strategy for promoting selective hydrocarbon production during CO₂ electroreduction.