Atomic Layer Deposition of Cu Electrocatalysts on Gas Diffusion Electrodes for CO2 Reduction.

Electrochemical reduction of CO2 using Cu catalysts enables the synthesis of C2+ products including C2H4 and C2H5OH. In this study, Cu catalysts were fabricated using plasma-enhanced atomic layer deposition (PEALD), achieving conformal deposition of catalysts throughout 3-D gas diffusion electrode (GDE) substrates while maintaining tunable control of Cu nanoparticle size and areal loading. The electrochemical CO2 reduction at the Cu surface yielded a total Faradaic efficiency (FE) > 75% for C2+ products. Parasitic hydrogen evolution was minimized to a FE of ∼10%, and a selectivity of 42.2% FE for C2H4 was demonstrated. Compared to a line-of-sight physical vapor deposition method, PEALD Cu catalysts show significant suppression of C1 products compared to C2+, which is associated with improved control of catalyst morphology and conformality within the porous GDE substrate. Finally, PEALD Cu catalysts demonstrated a stable performance for 15 h with minimal reduction in the C2H4 production rate.