Recycling urine for bioelectrochemical hydrogen production using a MoS2 nano carbon coated electrode in a microbial electrolysis cell

In this study, a novel molybdenum disulfide (MoS2) nano-carbon (NC) coated cathode was developed for hydrogen production in a microbial electrolysis cell (MEC), while treating simulated urine with 2–6 times dilution (conductivity <20 mS cm−1). MoS2 nanoparticles were electrodeposited on the NC coated cathodes at −100, −150 and −200 μA cm−2 and their performances were evaluated in the MEC. The chronopotentiometry (CP) tests showed the improved catalytic activity of MoS2-NC cathodes with much lower cathode overpotential than non-MoS2 coated electrodes. The MoS2-NC200 cathode, electrodeposited at −200 μA cm−2, showed the maximum hydrogen production rate of 0.152 ± 0.002 m3 H2 m−2 d−1 at 0.9V of Eap, which is comparable to the previously reported Pt electrodes. It was found that high solution conductivity over 20 mS cm−1 (>600 mg L−1 NH3-N) can adversely affect the biofilm architecture and the bacterial activity at the anode of the MEC. Exoelectrogenic bacteria for this system at the anode were identified as Tissierella (Clostridia) and Bacteroidetes taxa. Maximum ammonia-nitrogen (NH3-N) and phosphorus (PO43--P) removal were 68.7 and 98.6%, respectively. This study showed that the newly fabricated MoS2-NC cathode can be a cost-effective alternative to the Pt cathode for renewable bioelectrochemical hydrogen production from urine.