Engineering intense Ru–TiO2 interaction for robust hydrogen oxidation reaction†

Developing high-performance ruthenium (Ru)-based electrocatalysts for alkaline hydrogen oxidation reaction (HOR) is crucial for the practical application of anion exchange membrane fuel cells. However, the inherent high oxophilicity of Ru leads to severe performance degradation at elevated anodic potentials. Herein, we construct a Ru/TiO₂ heterostructure electrocatalyst via a reverse two-step approach that enhances the interaction between Ru and TiO₂. The optimal Ru/TiO₂-400 electrocatalyst exhibits remarkable HOR performance with a mass activity of 0.559 A mg_Ru⁻¹ at 50 mV (vs. RHE) and a specific exchange current density of 0.484 mA cm⁻², which are 2.0 and 4.8 times higher than those of Pt/C, respectively. Notably, the Ru/TiO₂-400 electrocatalyst exhibits remarkable HOR performance with minimal current degradation even at anodic potentials up to 0.6 V (vs. RHE). Experimental results demonstrate that the robust Ru–Ti and Ru–O bonds derived from the intense Ru–TiO₂ interaction effectively prevent Ru from combining with O from the adsorbed OH, thereby enhancing Ru inoxidizability at high potentials. Moreover, the metallic Ru becomes electron rich due to the electron transfer from TiO₂ to Ru, which weakens the adsorption of H reaction intermediates. The Ru and TiO₂ domains at Ru–TiO₂ interfaces are the optimal H and OH adsorption sites, respectively. Therefore, the enhanced electrocatalytic performance of the Ru/TiO₂ electrocatalyst is attributed to the robust and multifunctional Ru–TiO₂ interfaces with intense Ru–TiO₂ interaction.