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 ^*CO_B and its further hydrogenation to ^*COH, and as such, the subsequent coupling of ^*COH and ^*CO_L eventually generates ethanol. As a result, the optimal Cu_1.22V_0.19Se 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.