Regulation of the Work Function Difference Promotes In Situ Phase Transition of WO3-x for Efficient Formate Electrooxidation

Interfacial Push-Pull Dynamics Enable Rapid Had 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 (Had) 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 Had from the Pd active sites. Second, the TiO2-P support diminishes the energy barrier for Had transfer from the Pd sites to the support itself, "pulling" Had 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 mgPd-1 and outperforms the Pd/TiO2 catalyst (2.39 A mgPd-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.

Modulating the d-Band Center of Palladium via Ethylene Glycol Modification: Accelerating Had Desorption for Enhanced Formate Electrooxidation

This study addresses the critical challenge in alkaline direct formate fuel cells (DFFCs) of slow formate oxidation reaction (FOR) kinetics as a result of strong hydrogen intermediate (Had) adsorption on Pd catalysts. We developed WO3-supported Pd nanoparticles (EG-Pd/WO3) via an organic reduction method using ethylene glycol (EG), aiming to modulate the d-band center of Pd and alter Had adsorption dynamics. Cyclic voltammetry demonstrated significantly improved Had desorption kinetics in EG-Pd/WO3 catalysts. Density functional theory (DFT) calculations revealed that the presence of EG reduces the d-band center of Pd, leading to weaker Pd-H bonds and enhanced Had desorption during the FOR. This research provides a new approach to optimize catalyst efficiency in DFFCs, highlighting the potential for more effective and sustainable energy solutions through advanced material engineering.