In-situ reconstruction of active bismuth for enhanced CO2 electroreduction to formate

• NO 3 − -modulated Bi 2 O 2 CO 3 improves reconstruction for CO 2 -to-formate reduction. • Formate selectivity surpassed 90 % from −0.7 to −1.1 V with 85 % iR compensation. • The formate partial current density reached up to 329 mA cm −2 in a flow cell. • 45 h stability at 100 mA cm −2 with >90 % formate selectivity was achieved. The electrocatalytic CO 2 reduction reaction (CO 2 RR) to carbon-based fuels represents a promising strategy for carbon neutrality. Bi-based materials have emerged as leading candidates for CO 2 RR towards formate. However, dynamic reconstruction under actual CO 2 RR conduction imposes a challenge for the well-designed pristine Bi-based catalyst to deliver electrocatalytic activity. Herein, we report a high-efficient Bi catalyst which is in-situ formed via electrochemical activation of NO 3 − modulated Bi 2 O 2 CO 3 during CO 2 RR. The in-situ and ex-situ characterizations demonstrate that a directional reconstruction has been achieved under NO 3 − adjustment, in which the reinforced configuration focuses on the ordered Bi planar surface. The peak Faradaic efficiency for formate (FE HCOO − ) of 97 % is achieved at −0.9 V vs . RHE and a potential region with FE HCOO − over 90 % ranges from −0.7 to −1.1 V. Additionally, the formate partial current density reaches up to 329 mA cm −2 in a gas diffusion electrode configuration. The outstanding durability is evidenced through its stable and efficient formate production over 45 h. Moreover, the in-situ attenuated total reflection infrared and Raman analysis reveals that the *OCHO is the key intermediate for CO 2 RR towards formate and the in-situ generated Bi renders the favorable interaction with *OCHO intermediate, thus promoting CO 2 RR performance.