Carbon dioxide (CO₂) electroreduction reaction (CO₂RR) offers a promising strategy for the conversion of CO₂ into valuable chemicals and fuels. CO2₊R 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 of −1.6 A cm⁻² for multicarbon products (jc₂₊), and jc₂₊ 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.
Mingxu Sun, Jiamin Cheng and Miho Yamauchi, Gas diffusion enhanced electrode with ultrathin superhydrophobic macropore structure for acidic CO₂ electroreduction, Nature Communications, 2024