Interfacial Push-Pull Dynamics Enable Rapid H_ad Desorption for Enhanced Formate Electrooxidation

The electrocatalytic conversion of formate in alkaline solutions is of paramount significance in the realm of fuel cell applications. Nonetheless, the adsorptive affinity of adsorbed hydrogen (H_ad) on the catalyst surface has traditionally impeded the catalytic efficiency of formate in such alkaline environments. To circumvent this challenge, our approach introduces an interfacial push-pull effect on the catalyst surface. This mechanism involves two primary actions: First, the anchoring of palladium (Pd) nanoparticles on a phosphorus-doped TiO₂ substrate (Pd/TiO₂-P) promotes the formation of electron-rich Pd with a downshifted d band center, thereby "pushing" the desorption of H_ad from the Pd active sites. Second, the TiO₂-P support diminishes the energy barrier for H_ad transfer from the Pd sites to the support itself, "pulling" H_ad to effectively relocate from the Pd active sites to the support. The resultant Pd/TiO₂-P catalyst showcases a remarkable mass activity of 4.38 A mg_Pd^-1 and outperforms the Pd/TiO₂ catalyst (2.39 A mg_Pd^-1) by a factor of 1.83. This advancement not only surmounts a critical barrier in catalysis but also delineates a scalable pathway to bolster the efficacy of Pd-based catalysts in alkaline media.