Preanodized Cu Surface for Selective CO Electroreduction to C or C Products.

The electrochemical CO reduction over Cu catalysts has shown great potential in producing a wide range of valuable chemicals, but it is still plagued by a poor controllability on product distribution. Herein, we demonstrate an effective regulation of CO reduction paths through a preanodization treatment of Cu foil electrodes in different electrolytes. The Cu electrode exhibits a superior C and C product selectivity after being preanodized in NaClO (Cu-) and NaHPO electrolyte (Cu-), respectively. Combined with electrochemical Raman, ATR-SEIRAS, and SEM characterizations, the preferential C path is due to the deposition of many Cu nanocrystals with dominant Cu(111) facets on the Cu- electrode. In contrast, the preferential C path over the Cu- is attributed to formation of a unique Cu nanodendritic morphology, which strengthens the *CO intermediate adsorption and induces an environment of low local HO/CO stoichiometric ratio, thus facilitating C-C coupling for C production. Our findings may shed light on the rational control of the CO reduction path through engineering of the Cu surface structure.