Pressure-Dependent CO 2 Electroreduction to Methane over Asymmetric Cu-N 2 Single-Atom Sites.

Single-atom catalysts (SACs) with unitary active sites hold great promise for realizing high selectivity toward a single product in the CO 2 electroreduction reaction (CO 2 RR). However, achieving high Faradaic efficiency (FE) of multielectron products like methane on SACs is still challenging. Herein, we report a pressure-regulating strategy that achieves 83.5 ± 4% FE for the CO 2 -to-CH 4 conversion on the asymmetric Cu-N 2 sites, representing one of the best CO 2 -to-CH 4 performances. Elevated CO 2 pressure was demonstrated as an efficient way to inhibit the hydrogen evolution reaction via promoting the competing adsorption of reactant CO 2 , regardless of the nature of the active sites. Meanwhile, the asymmetric Cu-N 2 structure could endow the Cu sites with stronger electronic coupling with *CO, thus suppressing the desorption of *CO and facilitating the following hydrogenation of *CO to *CHO. This work provides a synergetic strategy of the pressure-induced reaction environment regulating and the electronic structure modulating for selective CO 2 RR toward targeted products.