Direct electrochemical conversion of CO₂ to ethanol offers a promising strategy to lower CO₂ emissions while storing energy from renewable electricity. However, current electrocatalysts offer only limited selectivity toward ethanol. Here we report a carbon-supported copper (Cu) catalyst, synthesized by an amalgamated Cu–Li method, that achieves a single-product Faradaic efficiency (FE) of 91% at −0.7 V (versus the reversible hydrogen electrode) and onset potential as low as −0.4 V (reversible hydrogen electrode) for electrocatalytic CO₂-to-ethanol conversion. The catalyst operated stably over 16 h. The FE of ethanol was highly sensitive to the initial dispersion of Cu atoms and decreased significantly when CuO and large Cu clusters become predominant species. Operando X-ray absorption spectroscopy identified a reversible transformation from atomically dispersed Cu atoms to Cu_n clusters (n = 3 and 4) on application of electrochemical conditions. First-principles calculations further elucidate the possible catalytic mechanism of CO₂ reduction over Cu_n.

将CO ₂直接电化学转化为乙醇提供了一种有前途的策略，可降低CO ₂排放，同时存储可再生电力的能量。然而，当前的电催化剂对乙醇仅提供有限的选择性。在这里，我们报告了一种碳载铜（Cu）催化剂，它是通过混合Cu-Li方法合成的，在-0.7 V时（相对于可逆氢电极）和起始电势可实现91％的单产品法拉第效率（FE）。电催化CO _2的电压低至-0.4 V（可逆氢电极）-乙醇转化。催化剂在16小时内稳定运行。乙醇的FE对Cu原子的初始分散高度敏感，当CuO和大的Cu团簇成为主要物种时，乙醇的FE显着降低。Operando X射线吸收光谱法确定了 在施加电化学条件下从原子分散的Cu原子到Cu _n团簇（n = 3和4）的可逆转变。第一性原理计算进一步阐明了在Cu _n上还原CO ₂的可能催化机理。