Pd-modified Bi2O3 catalyst for efficient CO2 electrolysis to formic acid

Formic acid (HCOOH) production from direct CO 2 electrolysis is suggested to be one of the most economically viable products. However, its commercial viability remains challenging in highly active and selective electrocatalysts. Here, we report that palladium (Pd) doping has a profound positive impact on the electrocatalytic activity of bismuth oxide (Bi 2 O 3 ). The introduction of Pd increases the current density and Faradaic efficiency of HCOOH (FE HCOOH ) in flow cell system. As a result, the optimized Pd-Bi catalyst exhibits a FE HCOOH of 99.1 % at −0.7 (V vs RHE). Operating experimental studies coupled with theoretical calculations reveal that the Pd modified active sites exhibit near-optimal binding energy for the key *OCHO intermediate, which is more conducive to the generation of formic acid. Furthermore, the use of an asymmetric low-frequency pulsed strategy stabilizes the active sites, ensuring sustained catalytic performance. This study highlights the potential of Pd-doped Bi 2 O 3 as a promising candidate for efficient and selective CO 2 electroreduction to formic acid.