Tailoring CO<sub>2</sub> Adsorption Configuration with Spatial Confinement Switches Electroreduction Product from Formate to Acetate
Hua‐Qin Wang, Heyu Sui, Ya-Long Ding, Ying Yang, Yaqiong Su, Hu Li
Abstract
Multi-proton-coupled electron transfer, multitudinous intermediates, and unavoidable competing hydrogen evolution reaction during CO 2 electroreduction make it tricky to control high selectivity for specific products. Here, we present spatial confinement of Fe single atoms (FeN 2 S 2 ) by adjacent FeS clusters (Fe 4 S 4 ) to orientate the transition of CO 2 adsorption configuration from C,O-side to O-end, which triggers a shift of activated CO 2 from first-step protonation to C–C coupling, thus switching the target product from HCOOH in high Faraday efficiency (FE: 90.6%) on FeN 2 S 2 to CH 3 COOH (FE: 82.3%) on Fe 4 S 4 /FeN 2 S 2 . The adsorption strength of *OCHO upon the solitary FeN 2 S 2 site is linearly related to the coordination number of Fe–S, with HCOOH predominantly produced over single-atom FeN 2 S 2 (ortho-substituted S atoms). Fe 4 S 4 cluster functions as a switch for a specific reduction product, which can not only optimize the spatial and electronic structure of the neighboring FeN 2 S 2 but also impel complete reduction of CO 2 to the hydrocarbon intermediate *CH 3, followed by coupling of CO 2 * and *CH 3 via the single-atom cluster synergistic catalysis of Fe 4 S 4 /FeN 2 S 2 . This spatial confinement strategy provides a new avenue to modulate the reactant adsorption model for desirable reaction pathways, with potential applications in diverse multistep electrochemical processes of controlled selectivity.