Bismuth Silicate Catalyst for Efficient Electrocatalytic CO 2 Reduction and Electrolyte‐Free Formic Acid Production

Abstract The rising atmospheric CO 2 levels pose significant environmental challenges. Electrocatalytic CO 2 reduction offers a promising approach for converting CO 2 into valuable chemicals such as formate or formic acid. However, the development of efficient electrocatalysts, a deeper mechanistic understanding, and the minimization of energy consumption during product purification remain critical challenges to practical carbon utilization. Here, layered Bi 2 SiO 5 is designed as a pre‐catalyst, which undergoes electrochemical reconstruction into a Bi@Bi 2 O 2 CO 3 composite. The catalyst achieves a Faradaic efficiency for formate of 95.8% at −1.06 V and maintains over 90% across a wide potential range, outperforming Bi 2 O 2 CO 3 and Bi. In situ characterizations reveal that Bi 2 SiO 5 converts to Bi 2 O 2 CO 3 through anion exchange, followed by partial reduction to form Bi@Bi 2 O 2 CO 3 . Charge redistribution at the interface facilitates the proton‐coupled electron transfer of * CO 2 and desorption of * HCOOH, thereby enhancing formate production, as supported by theoretical calculations. Furthermore, integrating the catalyst into an electrolytic cell containing solid‐state electrolytes enables the continuous production of electrolyte‐free formic acid, simplifying product separation and purification. This work provides insights for the development of practical carbon utilization.