Mo 4+ -Doped CuS Nanosheet-Assembled Hollow Spheres for CO 2 Electroreduction to Ethanol in a Flow Cell.

Electrocatalytic CO 2 reduction reaction (CO 2 RR) to ethanol has been widely researched for potential commercial application. However, it still faces limited selectivity at a large current density. Herein, Mo 4+ -doped CuS nanosheet-assembled hollow spheres are constructed to address this issue. Mo 4+ ion doping modifies the local electronic environments and diversifies the binding sites of CuS, which increases the coverage of linear *CO L and produces bridge *CO B for subsequent *CO L -*COH coupling toward ethanol production. The optimal Mo 9.0% -CuS can electrocatalyze CO 2 to ethanol with a faradaic efficiency of 67.5% and a partial current density of 186.5 mA cm -2 at -0.6 V in a flow cell. This work clarifies that doping high valence transition metal ions into Cu-based sulfides can regulate the coverage and configuration of related intermediates for ethanol production during the CO 2 RR in a flow cell.