Here we report a synthesis of nickel cobalt oxysulfide nanocage trifunctional electrocatalysts by sulfurizing zeolitic imidazolate framework-67. Benefiting from the synergistic coupling of nickel cobalt oxysulfide and N-doped carbon polyhedron in a hollow dodecahedral structure, the nickel cobalt oxysulfide nanocages exhibit superior trifunctional electrocatalytic activity and durability towards oxygen reduction and evolution, and hydrogen evolution reactions in alkaline conditions. Moreover, the nickel cobalt oxysulfide nanocage trifunctional electrocatalysts are used in an air cathode for a rechargeable zinc-air battery and in both anode and cathode for overall water splitting, where the water splitting is directly powered by the assembled zinc-air battery. Such integrative power-to-hydrogen device can operate stably over 17 h without visible energy efficiency losses for hydrogen gas production.