Native frustrated Lewis pairs on core–shell In@InOxHy enhances CO2-to-formate conversion

Abstract

Strategies to efficiently activate CO₂ by strongly inhibiting the competitive hydrogen evolution reaction process are highly desired for practical applications of the electrochemical CO₂ reduction technique. Here, we assembled a core–shell In@InO_xH_y architecture on carbon black by one-step reduction of NaBH₄ as a CO₂-to-formate catalyst with high selectivity. The stable CO₂-to-formate reaction originates from the creation of steritic frustrated Lewis pairs (FLPs) on the InO_xH_y shell with In–O_Vs (O_Vs, oxygen vacancies) Lewis acid, and In–OH Lewis base. During CO₂ reduction, the electrochemically stable FLPs are capable of first capturing and stabilizing protons to protonate FLPs to In–H Lewis acid and In–OH₂ Lewis base due to its strong steric electrostatic field; then, CO₂ is captured and activated by the protonated FLPs to selectively produce formate. Our results demonstrated that FLPs can be created on the surface of oxyphilic single-metal catalysts efficient in accelerating CO₂ reduction with high selectivity.