Overcoming Interfacial Hydrogen Site-Blocking during Alkaline Formate Oxidation: Insights from Lattice-Compressed PdZr/C Catalysts

Improving the electrocatalytic conversion of formate in alkaline solutions is crucial for the commercial application of formate fuel cells. However, palladium-based catalysts used for formate oxidation reactions (FOR) face challenges due to the strong adsorption of hydrogen intermediates, resulting in lower catalytic efficiency in alkaline environments. Herein, we prepared a PdZr/C catalyst aimed at employing a doping-induced strain strategy to reduce the hydrogen binding energy of palladium and release more active sites for the oxidation of formate. Through density functional theory calculations and experimental investigations, we find that the lattice compression induced by Zr doping regulates the electronic structure of Pd. Specifically, the incorporation of Zr dopant shifts the d-band center of Pd downward, weakening the binding energy of hydrogen at the Pd sites. This adjustment promotes the desorption of hydrogen intermediates, thus accelerating the FOR kinetics by alleviating the site-blocking effect. As a result, the PdZr/C catalyst exhibited a 2.4-fold increase in activity compared to the conventional Pd/C catalyst. It also achieved a lower peak potential and delivered a significantly higher peak current of 1917 mA mg^-1. These findings highlight the critical role of lattice strain in tuning the catalytic properties of Pd and offer valuable insights into the design of high-performance electrocatalysts for energy conversion technologies.