Innovative self-powered submersible microbial electrolysis cell (SMEC) for biohydrogen production from anaerobic reactors

► An innovative reactor for in situ microbial electrolysis hydrogen production. ► The hydrogen production increased along with acetate and buffer concentration. ► Electron losses occurred both in hydrogen and electricity production processes. ► Alternate function exchange between the two cell units can inhibit methanogenesis. ► Same microbial community structures in the anodic biofilms of the two cell units.