Sub-2 nm ultra-thin Bi2O2CO3 nanosheets with abundant Bi-O structures toward formic acid electrosynthesis over a wide potential window

The electrocatalytic reduction of CO2 to HCOOH (ERC-HCOOH) is one of the most feasible ways to alleviate energy crisis and solve environmental problems. Nevertheless, it remains a challenge for ERC-HCOOH to maintain excellent activity and selectivity in a wide potential window. Herein, ultra-thin flower-like Bi2O2CO3 nanosheets (NSs) with abundant Bi-O structures were in situ synthesized on carbon paper via topological transformation and post-processing. Faraday efficiency of HCOOH (FEHCOOH) reached 90% in a wide potential window (−1.5 to −1.8 V vs. Ag/AgCl). Significantly, excellent FEHCOOH (90%) and current density (47 mA·cm−2) were achieved at −1.8 V vs. Ag/AgCl. The X-ray absorption fine structure (XAFS) combined with density functional theory (DFT) calculation demonstrated that the excellent performance of Bi2O2CO3 NS was attributed to the abundant Bi-O structures, which was conducive to enhancing the adsorption of CO2* and OCHO* intermediates and can effectively inhibit hydrogen evolution. The excellent performance of Bi2O2CO3 NS over a wide potential window could provide new insights for the efficient electrocatalytic conversion of CO2.