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

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

CO2 electrocatalytic reduction (CO2ER) to multicarbon (C2+) products are heavily pursued because of their commercial values, whose efficiency and selectivity have both attracted tremendous attention. 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, we report that V-doped Cu2Se nanotubes with a hierarchical structure can be perfectly compatible with flow-cell and fulfil such a task, achieving CO2 electroreduction to ethanol with high efficiency and selectivity. As revealed by our experimental characterization and theoretical calculation, the substitutional vanadium doping alters the local charge distribution of Cu2Se 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 Cu1.22V0.19Se 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 the avenue for flow-cell CO2ER toward a single C2+ liquid fuel.