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-star binding. Using density functional theory studies, we found Pd-Cu promising for selective C2+ production over C-1, with the lowest Delta G(OCCOH)star and Delta(GOCCOH)star - Delta(GCHO)star. 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+.

Automated summary

Renewable electricity-powered CO2 reduction to multi-carbon (C2+) products is a promising route for low-carbon-footprint fuels and chemicals. Acidic conditions offer a solution to the consumption of input CO2 by the electrolyte, but also promote the hydrogen evolution reaction. This study presents a design strategy that suppresses the activity of hydrogen evolution reaction by maximizing the co-adsorption of CO and CO2 on Cu-based catalysts.