Simultaneous hydrogen generation and COD reduction in a photoanode-based microbial electrolysis cell

A phenolic precursor-based carbon film dispersed with cerium oxide (CeO2) and reduced graphene oxide (rGO) is prepared as the electrodes of a microbial electrolysis cell (MEC) for simultaneous hydrogen (H2) production and reduction of chemical oxygen demand (COD) in wastewater under visible light irradiation. The oxides are in situ dispersed in the polymerization reaction mixture during the synthesis stage of the phenolic film. The maximum Coulombic energy efficiency, overall H2 recovery and cathodic recovery of the CeO2-rGO/carbon film-based MEC are measured to be approximately 95, 93 and 98%, respectively at 1 V (Ag/AgCl), whereas COD reduction in the wastewater is measured to be approximately 95%. The improved hydrogen evolution and organic degradation are attributed to the electroconductive graphitic rGO and photocatalytic CeO2, respectively. The metal oxide-rGO-dispersed carbon nanocomposite film-based MEC provides an efficient means for simultaneously producing H2 and treating the organics-laden wastewater.