A three-dimensional self-standing Mo2C/nitrogen-doped graphene aerogel: Enhancement hydrogen production from landfill leachate wastewater in MFCs-AEC coupled system

A hydrothermal-annealing method was adopted to form nitrogen-doped graphene aerogel-supported molybdenum carbide (Mo2C/NGA) materials by using graphene oxide (GO), poly (propylene glycol) bis(2-aminopropyl ether) (D400 for short) and ammonium molybdate as precursors. The annealing temperature and GO/D400 wt ratio played an important role on the materials structure and electrocatalytic activity. When the annealing temperature reached to 800 °C, the Mo2C was formed as an active component and improved obviously the hydrogen evolution reaction (HER) activity. After introducing the appropriate amount of D400, the Mo2C/NGA material not only had a firm porous monolithic framework, but also presented an increasing HER activity. Further, the Mo2C/NGA-based microbial fuel cells-ammonia electrolysis cell (MFCs-AEC) coupled system was constructed and operated for higher hydrogen production. The coupled system produced hydrogen of 198 mL g-1Mo2C/NGA in simulated ammonia-rich wastewater. As using the actual landfill leachate wastewater as substrate, there was 79.2 mL g-1Mo2C/NGA of hydrogen production. All of these were attributed to the porous structure with an interconnected network and the nitrogen-doped structure of the NGA.