Microbial photoelectrochemical cell using hybrid CuO/ZnO/CuO and Shewanella oneidensis MR-1 anode for hydrogen production

[Display omitted] •First use of hybrid CuO/ZnO/CuO bio-photoanodes in M-PEC cells for H2 production.•CuO/ZnO/CuO photoanodes absorb a wide range of light from visible to infrared.•M-PEC cells achieve an H2 production rate of 13.6 ± 9.7 mmol/m2/day.•Hybrid bio-photoanodes retain 74 % of its initial current density over 2 days.•The use of hybrid bio-photoanodes simplifies the entire H2 production system. Microbial photoelectrochemical (M-PEC) cells, which consist of photoelectrodes and bacterial catalysts, are a promising and emerging technology that can produce hydrogen (H2) using solar energy. This is the first report that demonstrates H2 production using M-PEC cells with hybrid CuO/ZnO/CuO and Shewanella oneidensis MR-1 bio-photoanodes. Recently, ZnO/CuO nanoforests (NFRs) have attracted attention as photoanode materials owing to their high photocatalytic efficiency; however, their short lifetime and Cu2+ leaching made it difficult to use as a bio-photoanode in M-PEC cells. We therefore overcame these limitations by modifying ZnO/CuO NFRs using a simple calcination technique with melamine and Cu wires. CuO nanoparticles were formed on the surface of ZnO/CuO NFRs by calcination, resulting in a CuO/ZnO/CuO triple-layer photo-semiconductor with high light absorption capacity (from visible light to the IR region). The photocurrent generation of CuO/ZnO/CuO improves by 1.6 times upon light irradiation and S. oneidensis MR-1 inoculation. The M-PEC cell with the fabricated bio-photoanode (CuO/ZnO/CuO inoculated with S. oneidensis MR-1 under light irradiation) exhibits an H2 production rate of 13.6 ± 9.7 mmol/m2/d, which is 6 times higher than that of the cell without light irradiation (bio-anode) and without S. oneidensis MR-1 (abiotic-anode). This bio-photoanode-based M-PEC cell can produce H2 for 2 days while retaining 74 % of its initial current density. The enhanced photocatalytic activity and stability could be attributed to the synergistic effects of the electricity generation by S. oneidensis MR-1 and the suppression of charge recombination by the coupling of the photoexcited holes and biogenerated electrons.