Novel ZnS-ZnO composite synthesized by the solvothermal method through the partial sulfidation of ZnO for H 2 production without sacrificial agent

•ZnS-ZnO composites were synthesized by the solvothermal method from the partial sulfidation of ZnO at low temperatures.•The ZnS-ZnO composites were active for the H2 production without sacrificial agent and in absence of a co-catalyst.•The photocatalytic activity was improved up to five times when methanol was used as sacrificial agent.•The heterojunction formed between ZnO and ZnS improves the charge transfer increasing the H2 production.