Chlorine-Promoted Nitrogen and Sulfur Co-Doped Biocarbon Catalyst for Electrochemical Carbon Dioxide Reduction

The conversion of carbon dioxide (CO2) to high value-added products is a forward-looking work, and has a good application prospect in mitigating energy crisis and climate problems. Recently, the electrochemical CO2 reduction reaction (ECRR) has attracted wide attention because of its controllable target products and high conversion efficiency. Here, a sulfur-nitrogen co-doped porous biocarbon catalyst derived from biomass lignin is reported, which has a high Faradaic efficiency (FE) of 95.9 % for ECRR to CO at a low overpotential of 490 mV and the corresponding average current density and yield of CO are -1.98 mA cm(-2) and 8.8 L m(-2) h(-1), respectively. During up to 18 hours of stability test, there was no significant change in catalyst activity and selectivity of CO and H-2. Besides, we systematically demonstrated that nitrogen doping is beneficial to the selectivity for ECRR to CO, and the adsorbed chlorine on the surface of biocarbon derived from hydrochloric acid washing greatly enhances the activity of ECRR, and thereby increases the yield of CO.