High-Power CO 2 -to-C 2 Electroreduction on Ga-Spaced, Square-like Cu Sites.

The electrochemical conversion of CO 2 into multicarbon (C 2 ) products on Cu-based catalysts is strongly affected by the surface coverage of adsorbed CO (*CO) intermediates and the subsequent C-C coupling. However, the increased *CO coverage inevitably leads to strong *CO repulsion and a reduced C-C coupling efficiency, thus resulting in suboptimal CO 2 -to-C 2 activity and selectivity, especially at ampere-level electrolysis current densities. Herein, we developed an atomically ordered Cu 9 Ga 4 intermetallic compound consisting of Cu square-like binding sites interspaced by catalytically inert Ga atoms. Compared to Cu(100) previously known with a high C 2 selectivity, the Ga-spaced, square-like Cu sites presented an elongated Cu-Cu distance that allowed to reduce *CO repulsion and increased *CO coverage simultaneously, thus endowing more efficient C-C coupling to C 2 products than Cu(100) and Cu(111). The Cu 9 Ga 4 catalyst exhibited an outstanding CO 2 -to-C 2 electroreduction, with a peak C 2 partial current density of 1207 mA cm -2 and a corresponding Faradaic efficiency of 71%. Moreover, the Cu 9 Ga 4 catalyst demonstrated a high-power (∼200 W) electrolysis capability with excellent electrochemical stability.