Mo⁴⁺-Doped CuS Nanosheet-Assembled Hollow Spheres for CO₂ Electroreduction to Ethanol in a Flow Cell

Electrocatalytic CO₂ reduction reaction (CO₂RR) to ethanol has been widely researched for potential commercial application. However, it still faces limited selectivity at a large current density. Herein, Mo⁴⁺-doped CuS nanosheet-assembled hollow spheres are constructed to address this issue. Mo⁴⁺ 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 CO₂ 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 CO₂RR in a flow cell.