Synergistic effects between dual-photoelectrodes and bioanode enhance sustainable hydrogen and electricity production from wastewater

Abstract

Microbial photoelectrochemical systems (MPECs) is promising for sustainable energy and resources recovery from wastewater, however, the synergistic effects between the photoelectrode and bioelectrode remain unclear. In this study, a hybrid MPEC configurated with a Fe2O3 photo-bioanode and a black-silicon (b-Si) photocathode was proposed for sustainable electricity and H2 production from wastewater. The dual photoelectrodes utilized solar light to generate photoelectrons and holes with enhanced light absorption. Mixed-culture biofilm formed on the photo-bioanode generated electrons and protons from wastewater.. Photoelectrons were transferred from the photoanode to the bioanode, and later arrived at the photocathode for electricity and H2 production. The electrons transfer mechanisms were studied under different irradiation conditions. The system achieved a maximum current density of 0.8 mA/cm2 and a H2 production rate of 5.1 µmol/h/cm2 (113 µL/h/cm2) under 1 sun irradiation. The syngenetic effects between the photoelectrodes and the bioanode are significant for sustainable electricity and H2 production.