Selective\nCO<sub>2</sub> Reduction over γ‑Graphyne\nSupported Single-Atom Catalysts: Crucial Role of Strain Regulation

The two-electron CO<sub>2</sub> reduction\nreaction (2e-CO<sub>2</sub>RR) is the most promising process for realizing\nindustrial utilization\nof CO<sub>2</sub>, but it is hindered by the competitive hydrogen\nevolution reaction (HER) because of the comparable equilibrium potential.\nStrategies to enhance 2e-CO<sub>2</sub>RR activity and selectivity\nby suppressing HER are highly demanded. Inspired by the low in-plane\nYoung’s modulus of the recently synthesized γ-graphyne\n(GY), we propose tensile-strain regulation as an effective method\nto improve the selectivity of the CO<sub>2</sub>RR against HER. By\nmeans of constant-potential calculations and constrained ab initio\nmolecular dynamics simulations, we demonstrate the good stability\nand high CO<sub>2</sub>RR activity of GY-supported Co (Co-GY) single-atom\ncatalysts (SACs). The change in potential of zero charges of *COOH\nis revealed to be more sensitive to tensile strain than that of *H\nspecies on Co-GY SACs, resulting in a slower change of its adsorption\nenergy than that of *H species under working potentials and consequently\nenhanced CO<sub>2</sub>RR selectivity toward CO production. Besides,\nthe strain-dependent regulation mechanism also applies to other M-GY\nSACs, demonstrating strain regulation as an effective strategy for\ndesigning and manipulating SACs for the selective 2e-CO<sub>2</sub>RR.