Decoupling H-Release and OH- Management at Pd@TiO2 Interfaces for Efficient Alkaline Hydrogen Oxidation Reaction

Journal article, 2026

Operando-level insight into catalyst degradation and reaction mechanisms is essential for progress in the alkaline hydrogen oxidation reaction (HOR). Herein, these aspects are investigated using a core-shell Pd@TiO2/C catalyst synthesized by thermal reduction followed by atomic layer deposition. The obtained catalyst exhibits high stability and delivers a mass exchange current density (j 0,m) of 97.5 mA mgPd -1, more than three times that of uncoated Pd/C (27.5 mA mgPd -1). Identical location transmission electron microscopy reveals a growth-detachment degradation pathway for Pd/C during accelerated durability testing, whereas the TiO2 shell in Pd@TiO2/C effectively suppresses this degradation, resulting in enhanced structural stability. Operando X-ray absorption spectroscopy under device-relevant conditions demonstrates the complementary functions of the two components: hydrogen dissociates and forms PdH x on the Pd core, lowering its Fermi level and driving electron transfer from TiO2 to Pd, while the TiO2 shell facilitates hydrogen desorption and provides OH- adsorption sites, thereby accelerating the reaction kinetics. These findings elucidate the dual stabilizing and catalytic roles of TiO2 and suggest a promising strategy for the design of durable and efficient alkaline HOR catalysts.