The Role of Discrepant Reactive Intermediates on Ru‐Ru2P Heterostructure for pH‐Universal Hydrogen Oxidation Reaction

Developing highly efficient electrocatalysts for hydrogen oxidation reaction (HOR) under alkaline media is essential for the commercialization of alkaline exchange membrane fuel cell (AEMFC). However, the kinetics of HOR in alkaline media is complicated, resulting in orders of magnitude slower than that in acid, even for the state‐of‐the‐art Pt/C. Here, we find that Ru‐Ru2P/C heterostructure shows HOR performance with a non‐monotonous variation in a whole pH region. Unexpectedly, an inflection point located at pH≈7 is observed, showing an anomalous behavior that HOR activity under alkaline media surpasses acidic media. Combining experimental results and theoretical calculations, we propose the roles of discrepant reactive intermediates for pH‐universal HOR, while H* and H2O* adsorption strengths are responsible for acidic HOR, and OH* adsorption strength is essential for alkaline HOR. This work not only sheds light on fundamentally understanding the mechanism of HOR but also provides new designing principles for pH‐targeted electrocatalysts. The hydrogen oxidation reaction (HOR) performance of Ru‐Ru2P/C heterostructure is explored in the whole pH range. Unexpectedly, a non‐monotonous relationship between the HOR activities and the pH of electrolytes is observed. Moreover, its HOR performance in alkaline media is much higher than that in acidic media, highlighting the role of discrepant intermediates for pH‐universal HOR.