High carbon utilization in CO₂ reduction to multi-carbon products in acidic media

Renewable electricity-powered CO₂ reduction to multi-carbon (C₂₊) products offers a promising route to realization of low-carbon-footprint fuels and chemicals. However, a major fraction of input CO₂ (>85%) is consumed by the electrolyte through reactions with hydroxide to form carbonate/bicarbonate in both alkaline and neutral reactors. Acidic conditions offer a solution to overcoming this limitation, but also promote the hydrogen evolution reaction. Here we report a design strategy that suppresses hydrogen evolution reaction activity by maximizing the co-adsorption of CO and CO₂ on Cu-based catalysts to weaken H* binding. Using density functional theory studies, we found Pd–Cu promising for selective C₂₊ production over C₁, with the lowest ∆G_OCCOH* and ∆G_OCCOH* - ∆G_CHO*. We synthesized Pd–Cu catalysts and report a crossover-free system (liquid product crossover <0.05%) with a Faradaic efficiency of 89 ± 4% for CO₂ to C₂₊ at 500 mA cm⁻², simultaneous with single-pass CO₂ utilization of 60 ± 2% to C₂₊.