V‐Doped Cu2Se Hierarchical Nanotubes Enabling Flow‐Cell CO2 Electroreduction to Ethanol with High Efficiency and Selectivity

CO2 electrocatalytic reduction (CO2 ER) to multicarbon (C2+ ) products is heavily pursued because of their commercial values, and the efficiency and selectivity have both attracted tremendous attention. A flow-cell is a device configuration that can greatly enhance the conversion efficiency but requires catalysts to possess high electrical conductivity and gas permeability; meanwhile, the catalysts should enable the reaction pathway to specific products. Herein, it is reported that V-doped Cu2 Se nanotubes with a hierarchical structure can be perfectly compatible with flow-cells and fulfil such a task, achieving CO2 electroreduction to ethanol with high efficiency and selectivity. As revealed by the experimental characterization and theoretical calculation, the substitutional vanadium doping alters the local charge distribution of Cu2 Se and diversifies the active sites. The unique active sites promote the formation of bridge *COB and its further hydrogenation to *COH, and, as such, the subsequent coupling of *COH and *COL eventually generates ethanol. As a result, the optimal Cu1.22 V0.19 Se nanotubes can electrocatalyze CO2 to ethanol with a Faradaic efficiency of 68.3% and a partial current density of -207.9 mA cm-2 for the single liquid product of ethanol at -0.8 V in a flow-cell. This work provides insights into the materials design for steering the reaction pathway toward C2+ products, and opens an avenue for flow-cell CO2 ER toward a single C2+ liquid fuel.