Effects of S‐Vacancy on the <scp> CO ₂ RR </scp> in Co‐Doped <scp> SnS ₂ </scp> Monolayer

ABSTRACT Electrochemical CO 2 reduction reaction (CO 2 RR) to value‐added chemicals offers a promising route for carbon neutrality. It has been reported that the Co‐anchored SnS 2 monolayer (Co@SnS 2 ) exhibits exceptional catalytic performance in the CO 2 RR toward HCOOH production. As the most prevalent intrinsic point defect in SnS 2 , S‐vacancy may alter the catalytic performance. Herein, first‐principles calculations were employed to systematically study the effects of S‐vacancy on the CO 2 RR in Co@SnS 2 . The S‐vacancy near the doped‐Co atom affects the adsorption of CO 2 molecules and impairs the activation of CO 2 . Besides, it increases the free energy of the *COOH intermediate and disfavors the generation of the *HCOOH intermediate. Consequently, the presence of S‐vacancy diminishes the catalytic performance of the Co@SnS 2 monolayer for the CO 2 RR toward HCOOH. These findings enrich the fundamental understanding of the S‐vacancy‐mediated regulation of CO 2 RR performance in the 2D SnS 2 ‐based catalysts and provide valuable experimental guidance for the rational design of high‐performance HCOOH‐selective CO 2 RR catalysts.