RuxMoS2 interfacial heterojunctions achieve efficient overall water splitting and stability in both alkaline and acidic media under large current density exceeding 100 mA cm-2

•Special nanostructures with ultrathin Ru@MoS2 shells and crystalline Ru nuclei have been formed by modifying MoS2 nanoparticles with Ru.•Ru doping and O vacancy have positive effects on each other formation energies.•Cooperation of Ru doping and O vacancy have strong effects on both thermodynamics and kinetic of the H2 activation. RuO2 has attracted considerable attention as a potential acid-alkali OER electrocatalyst. Exploring highly active Rux/MoS2@NF (x = 1, 2, 3 mmol) electrocatalysts for acidic oxygen evolution reaction (OER) is critical for advancing H2 production via water electrolysis using proton exchange membrane electrolyzer. For an alkaline current density of 10 mA cm−2, Ru2/MoS2@NF has severely low HER and OER overpotentials of -38.44 and 39.42 mV. Tafel has a smaller slope of 43.32 and 24.58 mV dec−1 and exceptional stability exceeding 600 h At 0.5 M H2SO4, Ru2/MoS2@NF at 100 mA cm−2 current density, OER is only 336.2 mV, considerably better than commercial Pt/C. In addition, doping Ru into MoO6 induces structural defects to generate oxygen vacancies, increasing the Mo6+/Mo4+ ratio. In situ Raman analyses showed that Ru doping has numerous structural defects, there was an increase in Mo−O active species at octahedral sites in Rux/MoS2, indicating accelerated generation of the key *O intermediates for enhanced OER kinetics. This work provides insight into the design of Ru based electrocatalysts that can considerably improve the performance of acidic OER, provides a roadmap for achieving efficient, economical and sustainable electrolysis of water for hydrogen production, and provides a roadmap for the design and commercialization of materials. [Display omitted]