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

Carbon dioxide (CO2) electroreduction reaction (CO2RR) offers a promising strategy for the conversion of CO2 into valuable chemicals and fuels. CO2RR in acidic electrolytes would have various advantages due to the suppression of carbonate formation. However, its reaction rate is severely limited by the slow CO2 diffusion due to the absence of hydroxide that facilitates the CO2 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 CO2 diffusion is highly enhanced. This GDE retains its applicability even under mechanical deformation conditions. The CO2RR 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 (C2+), and $$ {j}_{{{{{{\rm{C}}}}}}_{2+}}$$ j C 2 + of −0.34 A cm−2 when applying dilute 25% CO2. In a highly acidic environment, C2+ formation occurs via a second order reaction which is controlled by both the catalyst and its hydroxide.