Gas diffusion enhanced electrode with ultrathin superhydrophobic macropore structure for acidic CO2 electroreduction

Abstract Carbon dioxide (CO 2 ) electroreduction reaction (CO 2 RR) offers a promising strategy for the conversion of CO 2 into valuable chemicals and fuels. CO 2 RR in acidic electrolytes would have various advantages due to the suppression of carbonate formation. However, its reaction rate is severely limited by the slow CO 2 diffusion due to the absence of hydroxide that facilitates the CO 2 diffusion in an acidic environment. Here, we design an optimal architecture of a gas diffusion electrode (GDE) employing a copper-based ultrathin superhydrophobic macroporous layer, in which the CO 2 diffusion is highly enhanced. This GDE retains its applicability even under mechanical deformation conditions. The CO 2 RR in acidic electrolytes exhibits a Faradaic efficiency of 87% with a partial current density $$( {j}_{{{{\rm{C}}}}_{2+}})$$ ( j C 2 + ) of −1.6 A cm −2 for multicarbon products (C 2+ ), and $$ {j}_{{{{{{\rm{C}}}}}}_{2+}}$$ j C 2 + of −0.34 A cm −2 when applying dilute 25% CO 2 . In a highly acidic environment, C 2+ formation occurs via a second order reaction which is controlled by both the catalyst and its hydroxide.