Cr2O3 promotes the catalytic performance of Bi-based catalysts for electrochemical CO2 reduction to HCOOH

Abstract

Electrochemical CO2 reduction reaction (CO2RR) to formic acid is a much-anticipated way of converting excess CO2 to high-value-added products. Bismuth (Bi)-based materials are promising catalysts, but remain challenging in terms of activity and selectivity. Herein, we reported a composition manipulation strategy to achieve simultaneous high activity and selectivity for CO2RR towards formate by incorporating Lewis acid Cr2O3 into Bi. Specifically, a novel Bi-Cr2O3 crystalline-amorphous catalyst was prepared by electroreduction of bismuth chromate (Bi2(CrO4)3). The as-prepared catalyst shows nano-dendrites structure, promising the maximum exposure of active sites. The obtained Bi-Cr2O3 catalyst exhibits a high Faradic efficiency (FEformate, 93.3%) at −1.1 V vs reversible hydrogen electrode (RHE), and can achieve a remarkable current density of −40.7 mA cm−2 at the same potential. Meanwhile, the FEformate remains above 90% over a wide potential window (−0.8 ∼ −1.2 V vs RHE) and the stability can maintain for 13 hours at −0.9 V vs RHE with high selectivity (>90%) and stable physical phase. Furthermore, the Zn-CO2 battery assembled with a Bi-Cr2O3 catalyst achieves the greatest power density of 4.63 mW cm−2 and could maintain cyclic charge/discharge stability for 40 hours.