N-doped macroporous carbon loading Mo2C as cathode electrocatalyst of hybrid neutral-alkaline microbial electrolysis cells for H2 generation

Microbial electrolysis cells (MECs) show promise in energy-effective hydrogen (H-2) production by harvesting electric energy from wastewater, while the implementation of such a desirable technique faces challenges of expensive cathodic catalysts and unfavorable neutral electrolyte for hydrogen evolution reaction (HER). This work presents a simple and cost-effective pyrolysis route to fabricate hybrid electrocatalysts of Mo2C loaded nitrogen-doped porous carbon (Mo2C/NC). The Mo2C/NC-800 catalyst delivers impressively high activity and durability in pH-varied electrolyte from alkali, neutral and acid, particularly in alkali condition (e.g. 1.0 M KOH) where the overpotential@10 mA cm(-2) is only 138 mV which is comparable to the commercial Pt/C catalysts. A hybrid neutral-alkaline MEC is therefore developed that uses Mo2C/NC as the cathode catalyst for H-2 production. The system requires an applied voltage of 1.0 V to achieve current density of similar to 20.0 A m(-2) at H-2 generation rate of 170.5 L m(-2) d(-1). This MEC performance is considerably higher than that of the traditional symmetric neutral counterpart that requires an applied voltage of 1.0 V to achieve current density of similar to 18.0 A m(-2) at H-2 generation rate of 159.4 L m(-2) d(-1) indicating promising potential of Mo2C/NC electrocatalyst to be applied in MEC device for H-2 generation.