A Zn regulated Bi nanosheet catalyst for improving electrochemical CO2 reduction to formate over a wide potential window

Abstract

Bi-based materials are promising catalysts for electrochemical reduction of carbon dioxide (CO₂) to formate, but remain challenging in terms of activity and stability. Herein, we report the facile synthesis of Zn-doped Bi nanosheets (Zn–Bi NSs) as a highly active and robust catalyst for electrochemical reduction of CO₂ to formate. Specifically, the Zn–Bi NS catalyst can be obtained using a hydrothermal method to prepare a Zn-decorated Bi₂O₂CO₃ nanosheet followed by electrochemical reduction treatment. The as-prepared catalyst exhibits a remarkable formate faradaic efficiency of 94.6% and a high formate current density of 40.5 mA cm⁻² at −1.2 V vs. reversible hydrogen electrode (RHE). In particular, the faradaic efficiency of formate remained at above 90% over a wide potential window from −0.8 to −1.2 V vs. RHE. In the H-type electrolytic cell, the Zn–Bi NS catalyst can be operated stably for 10 h at a cathode potential of −1.0 V vs. RHE with good retention of the physical phase.