Identification of pH-dependent synergy on Ru/MoS(2) interface: a comparison of alkaline and acidic hydrogen evolution

Engineering bifunctional interfaces for enhanced alkaline hydrogen evolution reaction (HER) kinetics is achieved by rational coupling of Ru nanoparticles and defect-rich MoS₂ nanosheets via a simple wet-chemical method. Comprehensive material characterizations, especially high-resolution transmission electron microscopy, reveal well-defined interfaces between both components, leading to interfacial synergy whereby Ru expedites water dissociation and nearby defect-rich MoS₂ enables favorable hydrogen adsorption for recombination into H₂. The designed Ru/MoS₂ material demonstrates remarkable catalytic activity towards alkaline HER (-13 mV at -10 mA cm⁻²) with stable operation after 12 h or 1000 cycles, which is superior to almost all Ru-based and MoS₂-based electrocatalysts and even outperforms commercial 20 wt% Pt/C at overpotentials larger than -78 mV in alkaline media. No improved HER activity is observed for Ru/MoS₂ in acidic electrolyte (-96 mV at -10 mA cm⁻²), which is even inferior to Ru/CP (-78 mV at -10 mA cm⁻²). The correlation between alkaline and acidic HER results confirms that the intrinsic HER activity of this material originates from the desired synergistic effect under alkaline conditions.Jinlong Liu, Yao Zheng, Dongdong Zhu, Anthony Vasileff, Tao Ling and Shi-Zhang Qia