Carbon dioxide electroreduction (CO₂R) is being actively studied as a promising route to convert carbon emissions to valuable chemicals and fuels. However, the fraction of input CO₂ that is productively reduced has typically been very low, <2% for multicarbon products; the balance reacts with hydroxide to form carbonate in both alkaline and neutral reactors. Acidic electrolytes would overcome this limitation, but hydrogen evolution has hitherto dominated under those conditions. We report that concentrating potassium cations in the vicinity of electrochemically active sites accelerates CO₂ activation to enable efficient CO₂R in acid. We achieve CO₂R on copper at pH <1 with a single-pass CO₂ utilization of 77%, including a conversion efficiency of 50% toward multicarbon products (ethylene, ethanol, and 1-propanol) at a current density of 1.2 amperes per square centimeter and a full-cell voltage of 4.2 volts.

二氧化碳电还原 (CO ₂ R) 作为一种将碳排放转化为有价值的化学品和燃料的有前景的途径正在被积极研究。然而，生产性减少的输入 CO ₂的比例通常非常低，对于多碳产品<2%；余量在碱性和中性反应器中与氢氧化物反应形成碳酸盐。酸性电解质将克服这一限制，但迄今为止，在这些条件下析氢占主导地位。我们报告说，在电化学活性位点附近浓缩钾阳离子可加速 CO ₂活化，从而在酸中实现高效的 CO ₂ R。我们使用单程 CO ₂在 pH <1 的情况下实现了铜上的CO ₂ R 77% 的利用率，包括在每平方厘米 1.2 安培的电流密度和 4.2 伏的全电池电压下，向多碳产品（乙烯、乙醇和 1-丙醇）的转化效率为 50%。