Developing highly efficient and stable non-precious metal-based electrocatalysts for alkaline hydrogen oxidation reaction (HOR) is essential for the commercialization of alkaline exchange membrane fuel cells but remains a big challenge. Here, a simple strategy for constructing the Ni/Ni 3 N heterostructure electrocatalyst with remarkable catalytic performance toward HOR under alkaline electrolyte is reported. Density functional theory calculations and experimental results reveal that the inter-regulated d-band center of interfacial Ni and Ni 3 N derived from electron transfer from Ni to Ni 3 N across the interface can lead to the weakened hydrogen binding energy of Ni and strengthened hydroxyl binding energy of Ni 3 N, which, together with the decreased formation energy of water species, contributes to the outstanding HOR performance.

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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.

Exploring efficient and economical electrocatalysts and understanding the mechanism for alkaline hydrogen oxidation reaction (HOR) are crucial to facilitate the development of alkaline polymer electrolyte fuel cells (APEFCs). Herein, Ru 2 P was synthesized and used as an anodic HOR electrocatalyst for APEFC, achieving a peak power density of 1.3 W cm −2 , the highest value among Pt-free anode electrocatalysts reported under the same conditions. From the density functional theory (DFT) calculations and experimental results, it was found that besides the optimized hydrogen binding energy, the enhanced adsorption strength of oxygenated species (OH*) and the reduced work function of Ru 2 P contributed to the enhanced HOR performance. The normalized exchange current densities of Ru 2 P/C were 0.37 mA cm ECSA −2 and 0.27 mA μg Ru −1, respectively, both approximately three times higher than those of Ru when conducted in the rotating disk electrode (RDE) system. Our work provides a new pathway for exploring highly active Pt-free HOR electrocatalysts and expanding the family of anodic electrocatalysts for APEFCs.

The kinetics of hydrogen oxidation reaction (HOR) under alkaline electrolyte, even for Pt, is orders of magnitude slower than that in acid; however, the origin that dominates the pH dependent HOR kinetics has not been unequivocally identified. Herein, Pd-Pd 4 S/C heterostructure is synthesized, and its HOR performance in the whole pH region is investigated. Unexpectedly, a non-monotonous variation between the current densities and pH is observed, whereas an inflection point occurring at a pH of around 7 is obtained. Moreover, the Pd-Pd 4 S/C heterostructure and its counterparts with almost identical hydrogen binding energies show HOR activity trends in accordance with their hydroxyl binding energies (OHBEs), highlighting the critical role of OHBE in enhancing HOR performance. The combination of experimental results and density functional theory calculations reveal that the electron transfer at the interface of Pd-Pd 4 S/C heterostructure promotes the OHBE and thereby accelerates the kinetics of alkaline HOR.