Hydrogen production from microbial fuel cells-ammonia electrolysis cell coupled system fed with landfill leachate using Mo2C/N-doped graphene nanocomposite as HER catalyst

In this work, we reported hydrogen production from ammonia-rich wastewater using series stacked microbial fuel cells (MFCs)-ammonia electrolytic cell (AEC) coupled system with Mo2C/N-doped graphene (Mo2C/N-rGO) nanocomposite as hydrogen evolution reaction (HER) catalyst. The electrocatalytic activity of Mo2C/N-rGO nanocomposite towards HER, the performance of simultaneous bioelectricity and hydrogen production as well as landfill leachate treatment of this coupled system were investigated under continuous parallel flow mode. Results demonstrated that four air-cathode MFCs in series stacking harvested the highest power density of 536 mW m−2 when fed with glucose and ammonium mixture, and meanwhile approximately 59 μL gMo2C/N-rGO−1 h−1 of hydrogen production rate was achieved with continuous bioelectricity supply to the AEC unit. As the substrate was shifted to actual landfill leachate (dilution ratio of 1:4), only ca. 143 mW m−2 of maximal output power was obtained from the series stacked MFCs, but it still accomplished 71% NH4+-N removal efficiency and about 42 μL gMo2C/N-rGO−1 h−1 of hydrogen production rate. This MFCs-AEC coupled bio-electrochemical system highlighted its potential for hydrogen production from real landfill leachate along with simultaneous chemical oxygen demand and ammonia-nitrogen removal without the need for external electricity supply, thus achieving the resource and energy re-utilization of ammonia-rich wastewater.