Improved microbial electrolysis cell hydrogen production by hybridization with a TiO₂ nanotube array photoanode

A microbial electrolysis cell (MEC) consumes the chemical energy of organic material producing, in turn, hydrogen. This study presents a new hybrid MEC design with improved performance. An external TiO₂ nanotube (TNT) array photoanode, fabricated by anodization of Ti foil, supplies photogenerated electrons to the MEC electrical circuit, significantly improving overall performance. The photogenerated electrons help to reduce electron depletion of the bioanode, and improve the proton reduction reaction at the cathode. Under simulated AM 1.5 illumination (100 mW cm^-2) the 28 mL hybrid MEC exhibits a H2 evolution rate of 1434.268 ± 114.174 mmol m^-3 h^-1, a current density of 0.371 ± 0.000 mA cm^-2 and power density of 1415.311 ± 23.937 mW m^-2, that are respectively 30.76%, 34.4%, and 26.0% higher than a MEC under dark condition.