Decoupling H‑Release and OH Management at Pd@TiO Interfaces for Efficient Alkaline Hydrogen Oxidation Reaction.

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@TiO/C catalyst synthesized by thermal reduction followed by atomic layer deposition. The obtained catalyst exhibits high stability and delivers a mass exchange current density ( ) of 97.5 mA mg , more than three times that of uncoated Pd/C (27.5 mA mg ). Identical location transmission electron microscopy reveals a growth-detachment degradation pathway for Pd/C during accelerated durability testing, whereas the TiO shell in Pd@TiO/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 on the Pd core, lowering its Fermi level and driving electron transfer from TiO to Pd, while the TiO shell facilitates hydrogen desorption and provides OH adsorption sites, thereby accelerating the reaction kinetics. These findings elucidate the dual stabilizing and catalytic roles of TiO and suggest a promising strategy for the design of durable and efficient alkaline HOR catalysts.