Effect mechanism of NO on electrocatalytic reduction of CO2 to CO over Pd@Cu bimetal catalysts

• The effect mechanism of NO on CO 2 RR-to-CO were investigated. • NO*, NOH*, and NH* adsorption on the Pd@Cu promote the CO 2 RR process. • NH 2 * and NH 3 * adsorption on the Pd@Cu are unfavourable for the CO 2 RR process. • ε d values of metal atoms vary significantly after intermediates adsorption. Electrocatalytic reduction of CO 2 (CO 2 RR) to chemicals with added value is a promising technology. Since the industrial CO 2 sources often contain NO x impurities, understanding the potential effects of these substances on CO 2 electrocatalysis is crucial for the practical applications. Herein, density functional theory (DFT) was used to study the effect of NO on electrocatalytic reduction of CO 2 to CO over Pd@Cu bimetal catalysts (BMCs). The results show that d-band center ( ε d ) and Mulliken charge values of metal atoms vary significantly after intermediates adsorption. The adsorption free energy of NO on the catalyst surface is lower than that of CO 2 . Thus, NO is more easily adsorbed on the catalyst surface and reduced to NH 3 . There are four intermediates (NOH*, N*, NH*, and NH 2 *) in the process of NO reduction (NORR). NO*, NOH*, and NH* adsorptions on the Pd@Cu BMCs promote the CO 2 RR process. However, NH 2 * and NH 3 * adsorptions on the Pd@Cu BMCs are unfavourable for the CO 2 RR process. N* adsorption on the Pd@Cu BMCs has no effect on CO 2 RR. The overpotential of Pd@Cu catalyst is 0.429 V, which is lower than that of many excellent catalysts reported. Pd@Cu has promising catalytic activity and NO tolerance for the CO 2 RR.