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Abstract The development of efficient and robust catalysts for hydrogen evolution reaction is crucial for advancing the hydrogen economy. In this study, we demonstrate that ultra-low coordinated hollow PtRuNi-Ox nanocages exhibit superior catalytic activity and stability across varied conditions, notably surpassing commercial Pt/C catalysts. Notably, the PtRuNi-Ox catalysts achieve current densities of 10 mA cm−2 at only 19.6 ± 0.1, 20.9 ± 0.1, and 21.0 ± 0.1 mV in alkaline freshwater, chemical wastewater, and seawater, respectively, while maintaining satisfied stability with minimal activity loss after 40,000 cycles. In situ experiments and theoretical calculations reveal that the ultra-low coordination of Pt, Ru, and Ni atoms creates numerous dangling bonds, which lower the water dissociation barrier and optimizing hydrogen adsorption. This research marks a notable advancement in the precise engineering of atomically dispersed multi-metallic centers in catalysts for energy-related applications.

Abstract Simultaneously activating metal and lattice oxygen sites to construct a compatible multi-mechanism catalysis is expected for the oxygen evolution reaction (OER) by providing highly available active sites and mediate catalytic activity/stability, but significant challenges remain. Herein, Fe and S dually modulated NiFe oxyhydroxide (R-NiFeOOH@SO4) is conceived by complete reconstruction of NiMoO4·xH2O@Fe,S during OER, and achieves compatible adsorbate evolution mechanism and lattice oxygen oxidation mechanism with simultaneously optimized metal/oxygen sites, as substantiated by in situ spectroscopy/mass spectrometry and chemical probe. Further theoretical analyses reveal that Fe promotes the OER kinetics under adsorbate evolution mechanism, while S excites the lattice oxygen activity under lattice oxygen oxidation mechanism, featuring upshifted O 2p band centers, enlarged d-d Coulomb interaction, weakened metal-oxygen bond and optimized intermediate adsorption free energy. Benefiting from the compatible multi-mechanism, R-NiFeOOH@SO4 only requires overpotentials of 251 ± 5/291 ± 1 mV to drive current densities of 100/500 mA cm−2 in alkaline media, with robust stability for over 300 h. This work provides insights in understanding the OER mechanism to better design high-performance OER catalysts.

Hydrogen energy is an important energy carrier, which is an ideal choice to meet energy demand and reduce harmful gas emissions. The green recycling of hydrogen energy depends on water electrolysis and hydrogen fuel cells, which involves hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER). The activity of HER/HOR in alkaline electrolyte, however, exhibits a significantly lower magnitude (2–3 orders) compared to that observed in an acidic medium, which hinders the development of alkaline water electrolysis and alkaline membrane fuel cells. Therefore, comprehending the characteristics of HOR/HER activity in alkaline electrolytes and elucidating its underlying mechanism is a prerequisite for the design of advanced electrocatalysts. Based on this background, this review will briefly summarize the explanations and controversies about the basic HOR mechanism, including bifunctional mechanism and hydrogen binding energy theory. Moreover, the crucial affecting factors of the HOR kinetics, such as d-band center theory, interfacial water recombination, alkali metal cations and electronic effects, are discussed. Thus, based on the above theories, the design principle, catalytic performance, and latest progress of HOR electrocatalysts are summarized. An outlook and future research perspectives of advanced catalysts for hydrogen energy recycling are addressed. This review is helpful to understand the latest development of HOR mechanism and design cost-effective and high-performance HOR electrocatalysts towards the production of clean renewable energies.

Hydrogen oxidation reaction (HOR) is an important semi‐cell reaction in the renewable energy conversion technology such as fuel cells. However, due to the slow reaction rate, the development of highly active catalysts remains a major challenge in alkaline fuel cells. Based on fundamental understanding of the sluggish kinetics toward the reaction mechanism in alkaline electrolytes, noble and non‐noble metal catalysts and their regulation strategies including geometry, composition, atom‐doping, oxyphilic site and substrate engineerings are analyzed and summarized in this review to seek for the possible breakthrough toward HOR catalytic performance enhancement. Eventually, challenges and opportunities faced by alkaline HOR, and potential future research trends are proposed. This review not only deepens the understanding of the hydrogen electrocatalysis mechanism, but also provides guidelines for the rational design of advanced HOR catalysts.