Effect of the built-in electric field in Pd/PdO-SnO2 hollow nanosphere electrocatalyst for formic acid electrooxidation

Pd is regarded as an efficient electrocatalyst for the formic acid electrooxidation reaction (FAEOR), yet it faces gradual deactivation due to CO poisoning over extended operation periods. This study introduces a novel strategy for enhancing electrocatalyst performance by constructing p-n heterojunctions to generate a built-in electric field (BIEF) in the Pd-based electrocatalyst, which optimizes the adsorption of intermediates and modulates their electronic structure. The experimental results revealed that the Pd/PdO-SnO2 hollow spheres catalysts (Pd/PdO-SnO2 HS) featured higher concentrations of surface adsorbed oxygenated (O-and O2-) and less CO intermediates, thereby endowing the catalyst with an efficient anti-CO poisoning ability. The Pd/PdO-SnO2 HS catalysts demonstrated superior FAEOR catalytic activity and stability, achieving a mass-specific activity of 1900.50 +/- 53.08 mA mg-1 Pd , 7.64 times greater than that of commercial Pd/C catalysts. Furthermore, the incorporation of bimetallic oxides significantly retarded the formic acid decomposition reaction (FADR) and enhanced the selectivity of the Pd/PdO-SnO2 HS catalysts towards FAEOR.