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

The electrocatalytic CO₂ reduction reaction (CO₂RR) to carbon-based fuels represents a promising strategy for carbon neutrality. Bi-based materials have emerged as leading candidates for CO₂RR towards formate. However, dynamic reconstruction under actual CO₂RR 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 NO₃⁻ modulated Bi₂O₂CO₃ during CO₂RR. The in-situ and ex-situ characterizations demonstrate that a directional reconstruction has been achieved under NO₃⁻ 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 versus 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 CO₂RR towards formate and the in-situ generated Bi renders the favorable interaction with *OCHO intermediate, thus promoting CO₂RR performance.