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

• A novel Mo 2 C loaded nitrogen-doped porous carbon (Mo 2 C/NC-800) is synthesized. • The Mo 2 C/NC-800 catalyst delivers impressively high activity and durability in all-pH electrolytes. • The hybrid neutral-alkaline MEC using Mo 2 C/NC-800 as the cathode catalyst can achieve current density of 20.0 mA m−2 at H 2 generation rate of 170.5 L m−2 d−1 only by applying voltage of 1.0 V. 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 Mo 2 C loaded nitrogen-doped porous carbon (Mo 2 C/NC). The Mo 2 C/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 Mo 2 C/NC as the cathode catalyst for H 2 production. The system requires an applied voltage of 1.0 V to achieve current density of ∼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 ∼18.0 A m−2 at H 2 generation rate of 159.4 L m−2 d−1 indicating promising potential of Mo 2 C/NC electrocatalyst to be applied in MEC device for H 2 generation. Novel Mo 2 C loaded nitrogen-doped porous carbon (Mo 2 C/NC-800) is successfully synthesized. The Mo 2 C/NC-800 catalyst delivers impressively high activity and durability in all-pH electrolytes, 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. The hybrid neutral-alkaline MEC using Mo 2 C/NC-800 as the cathode catalyst can achieve current density of 20.0 mA m−2 at H 2 generation rate of 170.5 L m−2 d−1 only by applying voltage of 1.0 V. [Display omitted] [ABSTRACT FROM AUTHOR]