Selective Electrochemical Conversion of Carbon Dioxide to Formic Acid on Oxide-Derived Sn_xZn Bimetallic Catalysts

The use of bimetallic catalysts for electrochemical CO2 reduction is considered a promising strategy to enhance the catalytic activity as well as the selectivity. Here, oxide-derived (OD) Sn–Zn bimetallic electrocatalysts are developed for the exclusive conversion of CO2 to HCOOH in an aqueous media. A pure Zn catalyst promotes conversion of CO2 to CO with a high Faradaic efficiency (FE) of 80%, whereas a Sn1Zn nanoporous catalyst drives an efficient CO2-to-HCOOH pathway with a high FEHCOOH of 80% at a moderate overpotential of −1.0 VRHE. The interaction between Sn and Zn plays an essential role in tuning the selectivity and catalytic activity. Sn–Zn bimetallic catalysts effectively localize electrons to metallic Sn, facilitating the selective and stable conversion of CO2 to HCOOH. Additionally, the catalyst maintains its initial efficiency even after a long-term (18 h) CO2 reduction reaction. This study experimentally demonstrates that OD Sn–Zn bimetallic catalysts are efficient and stable for reducing the CO2 gas to HCOOH.