Electrodeposited highly-oriented bismuth microparticles for efficient CO₂ electroreduction into formate

Bi is one of the most fascinating catalysts for the formation of HCOO⁻ towards CO₂ electroreduction. Herein, we developed electrodeposited angular-shaped Bi microparticles (Bi MP) with exposed surfaces of {003} and {101} planes as efficient catalyst for the electroreduction of CO₂ into HCOO⁻. During CO₂ electroreduction, Bi MP achieved a Faraday efficiency (FE) for HCOO⁻ of higher than 95% over a wide range of applied potential from −0.6 to −1.1 V versus reversible hydrogen electrode (vs. RHE), whereas the FE for HCOO⁻ of Bi nanoflakes (Bi NF) with exposed surfaces of {104} and {110} planes was around 70%. At −1.1 V vs. RHE, the partial current density for HCOO⁻ of Bi MP was −271.7 mA·cm⁻², 1.56 times as high as that of Bi NF. According to kinetic analysis and mechanistic study, highly-oriented surface of Bi MP not only facilitated Faradaic process and accelerated reaction kinetics via enhancing the CO₂ activation, but also restrained competing hydrogen evolution reaction, thus boosting catalytic performance of the electroreduction of CO₂ into HCOO⁻.