Ru Nanoparticles Encapsulated by Defective TiO 2 Boost the Hydrogen Oxidation/ Evolution Reaction

The development of efficient and durable electrocatalysts for the alkaline hydrogen oxidation/evolution reaction is crucial for anion exchange membrane fuel cells/water electrolyzers. However, designing such electrocatalysts poses a challenge due to the need for optimizing various adsorbates. Herein, highly dispersed Ru nanoparticles catalysts is reported encapsulated and supported by defective anatase phase of titanium dioxide (named as Ru NPs/def-TiO₂(A)) for boosting hydrogen-cycle electrocatalysis with robust anti-CO-poisoning in alkaline conditions. The Ru NPs/def-TiO₂(A) achieves a high-quality activity of 7.65 A mg_Ru ^-1, which is 23.2 and 9.5-fold higher than commercial Ru/C and Pt/C in alkaline HOR. Moreover, this catalyst exhibits an outstanding overpotential of 21 mV at 10 mA cm^-2 in alkaline HER. Hydrogen underpotential deposition (H_upd) and CO stripping experiments demonstrate that Ru NPs/def-TiO₂(A) has the optimized H*, OH*, and CO* adsorption strength, enabling the Ru NPs/def-TiO₂(A) catalyst to display excellent and robust HOR/HER performance under alkaline conditions. Using density functional theory calculations, the enhanced HOR performance mechanism for the Ru NPs/def-TiO₂(A) catalyst originates from the TiO₂ step face in contact with the Ru nanoparticles, indicating that the kinetics of water formation are considerably more favorable at the Ru NPs/def-TiO₂(A) interface.