In-situ constructing Bi@Bi2O2CO3 nanosheet catalyst for ampere-level CO2 electroreduction to formate

Bi-based electrocatalysts are prominent candidates to achieve CO2 reduction to formate with high selectivity but suffer from unsatisfied activity, stability, and ambiguous nature of active sites. Herein, the Bi@Bi2O2CO3 nanosheet catalyst is designed via an electrochemical in-situ reconstruction approach from BiPO4. The conversion processes were revealed by electrochemical in-situ Raman and FTIR spectroscopy. The obtained Bi@Bi2O2CO3 catalyst demonstrates high CO2 reduction performance (FEHCOOH ≈ 100%, jHCOOH ≈ −60 mA cm−2) and excellent stability of 110 h in H-type cell. Moreover, the Bi@Bi2O2CO3 delivers a remarkable formate partial current density up to −1.2 A cm−2 (production rate as 22.4 mmol cm−2 h−1) in the flow cell. DFT theoretical studies reveal the synergistic effect of Bi and Bi2O2CO3 at the interface played an important role in changing the adsorption behavior of reaction intermediates and further greatly reducing the activation barrier of the conversion of *OCHO to *HCOOH during CO2 reduction.