Active-site stabilized Bi metal-organic framework-based catalyst for highly active and selective electroreduction of CO2 to formate over a wide potential window

Bismuth-based materials have been validated to be a kind of effective electrocatalyst for electrocatalytic CO2 reduction (ECR) to formate (HCOO-). However, the established studies still encounter the problems of low current density, low selectivity, narrow potential window, and poor catalyst stability. Herein, a bismuth-terephthalate framework (Bi-BDC MOF) material was successfully synthesized. The optimized Bi-BDC-120 degrees C exhibited excellent activity, selectivity, and durability for formate production. At an operating potential of -1.1 V vs. RHE in 0.1 mol L-1 KHCO3 electrolyte, the ECR catalyzed by Bi-BDC-120 degrees C achieved a Faraday efficiency (FE) of 97.2% towards formate generation, and the total current density reached about 30 mA cm(-2). The operating potential window with FEformate values > 95% ranged in -0.9 to -1.5 V vs. RHE. The density-functional theory (DFT) calculation demonstrated that the (001) crystalline planes of Bi-BDC are preferable for the adsorption of CO2 and the conversion of *OCHO intermediates, thus ultimately promoting the electrocatalytic production of formate. Although the MOF structure of Bi-BDC-120 degrees C was insufficiently stabilized, the FEformate could be maintained at around 90% after 36 h of ECR operation. The long-term durability for formate production was attributed to the fact that the in situ reconstructed Bi2O2CO3 could retain the Bi-O active sites in the structure. These results offer an opportunity to design CO2 reduction electrocatalysts with high activity and selectivity for potential applications.

Automated summary

In this study, a bismuth-terephthalate framework material was synthesized and found to exhibit excellent formate production activity, selectivity, and durability. Density functional theory calculations also revealed the mechanism of its optimized structure in the electrocatalytic production of formate from CO2.