The massive depletion of fossil fuels has led to severe energy and environmental crisis, which urgently needs an in-depth research on the exploration of sustainable energy. Among various energy sources, hydrogen (H 2) is considered to be one of the most potential alternatives to traditional fossil fuels owing to its high energy density and environmental friendliness. [1] Electrochemical hydrogen evolution reaction (HER) is an attracting and scalable technology to split water into H 2 , which can use the renewable electricity as power to realize a hydrogen-based economy. [2] Metals with good conductivity and proton activation are promising electrocatalysts for HER. The past years have witnessed the great progress on metal-based catalysts for HER, where the noble metals, such as platinum (Pt) with near-zero overpotential and a very low Tafel slope for HER, are well known to meet the requirements in terms of commercial application. [3] However, the cherish scarcity and poor stability The electrochemical hydrogen evolution reaction (HER) is an attractive technology for the mass production of hydrogen. Ru-based materials are promising electrocatalysts owing to the similar bonding strength with hydrogen but much lower cost than Pt catalysts. Herein, an ordered macroporous superstructure of N-doped nanoporous carbon anchored with the ultrafine Ru nanoclusters as electrocatalytic micro/nanoreactors is developed via the thermal pyrolysis of ordered macroporous single crystals of ZIF-8 accommodating Ru(III) ions. Benefiting from the highly interconnected reticular macro-nanospaces, this superstrucure affords unparalleled performance for pH-universal HER, with order of magnitude higher mass activity compared to the benchmark Pt/C. Notably, an exceptionally low overpotential of only 13 mV@10 mA cm −2 is required for HER in alkaline solution, with a low Tafel slope of 40.41 mV dec −1 and an ultrahigh turnover frequency value of 1.6 H 2 s −1 at 25 mV, greatly outperforming Pt/C. Furthermore, the hydrogen generation rates are almost twice those of Pt/C during practical overall alkaline water splitting. A solar-to-hydrogen system is also demonstrated to further promote the application. This research may open a new avenue for the development of advanced electrocatalytic micro/nanoreactors with controlled morphology and excellent performance for future energy applications.

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