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

## TL;DR

A new Pd@TiO2 catalyst improves hydrogen oxidation reaction efficiency and stability in alkaline conditions.

## Contribution

A dual-function TiO2 shell is introduced to enhance both stability and catalytic performance in alkaline hydrogen oxidation.

## Key findings

- The Pd@TiO2/C catalyst achieves a mass exchange current density of 97.5 mA mgPd–1, significantly higher than uncoated Pd/C.
- TiO2 suppresses degradation of the catalyst structure during accelerated durability testing.
- TiO2 facilitates hydrogen desorption and OH– adsorption, accelerating reaction kinetics.

## Abstract

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.