(707g) Janus Heterostructured Bi-Cu2s Nanocrystals for Efficient CO2 Electroreduction to Formate

Electrochemical reduction of CO₂ (ECO₂RR) in alkaline media by using non-precious metal nanoparticles has been attracting tremendous research efforts. Previous work has shown that the electrochemical reduction of CO₂ to formate can be realized over low-cost bismuth (Bi)-based catalysts, and the Faradic efficiency (FE) of formate could reach 90%.[1] Nevertheless, the multimetallic heterostructured Bi catalysts have never been developed. In this work, we synthesized a novel heterostructured bismuth/cuprasulfide (Bi-Cu₂S) with a microphone-like morphology with a precisely controlled aspect ratio that has never been achieved before. These Bi-Cu₂S heterostructures are then used as electrocatalysts for CO₂ reduction in KHCO₃ electrolyte. By controlling the reaction conditions, e.g., the reaction temperature, the amount of reducing agent and degassing temperature, the optimal heterostructured Bi-Cu₂S catalysts enable highly efficient ECO₂RR with largely reduced overpotential (~240 mV lower than Bi), near-unity FE (>98%) for formate production, and high partial current density (2.4- and 5.2-fold higher J_HCOO- than Cu₂S and Bi at -1.0 V vs. reversible hydrogen electrode, RHE), outperforming most of the previous reports.