Hybrid biological/inorganic photocathode for H2 production based on a NiFeSe hydrogenase immobilized on electrodeposited CuGaS2

In order to mitigate global warming and pollution problems, new energy vectors need to be developed towards a fossil fuel-free society. Hydrogen is a great candidate for the role, since it can be cleanly obtained from water splitting. However, finding an efficient method that allows diminishing the high potentials required for the reaction is still a challenge to overcome. In order to tackle this task, a combination of a redox biocatalyst and an inorganic semiconductor that harnesses sunlight to enhance the H2 photoelectrochemical production has been studied. For this endeavor, we have developed a photocathode based on the p-type semiconductor copper gallium sulfide and the Desulfovibrio vulgaris Hildenborough NiFeSe-hydrogenase where the photoexcited semiconductor transfers excited electrons to the enzyme upon visible irradiation. The system is capable of producing photoelectrochemical biocatalytic proton reduction to H2 without any sacrificial agent while providing an approximately 400 mV decrease of the applied potential. [Display omitted] •We have developed a modified bioelectrode with FTO, CuGaS2 and a hydrogenase to produce H2 through water splitting.•The photo-bioelectrode produced H2 at potentials ~400 mV less negative than those reported for bioelectrocatalytic systems.•Hydrophilization of the surface enhanced electrodeposition and improved the photocurrents obtained.•The system is capable of H2 production, as we could test with mass spectrometry, with 86% faradaic yield.