Engineering intense Ru-TiO2 interaction for robust hydrogen oxidation reaction

Abstract

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 mgRu-1 at 50 mV (vs. RHE) and a specific exchange current density of 0.484 mA cm-2, which is 2.0 and 4.8 times higher than that 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 intermediate. The Ru and TiO2 domains at Ru-TiO2 interfaces are the optimal H and OH adsorption sites, respectively. Therefore, the enhanced electrocatalytic performance of Ru/TiO2 electrocatalyst is attributed to the robust and multifunctional Ru-TiO2 interfaces with intense Ru-TiO2 interaction.