Solar Water Splitting with a Hydrogenase Integrated in Photoelectrochemical Tandem Cells

Hydrogenases (H2ases) are benchmark electrocatalysts for H2 production, both in biology and (photo)catalysis in vitro. We report the tailoring of a p‐type Si photocathode for optimal loading and wiring of H2ase through the introduction of a hierarchical inverse opal (IO) TiO2 interlayer. This proton‐reducing Si|IO‐TiO2|H2ase photocathode is capable of driving overall water splitting in combination with a photoanode. We demonstrate unassisted (bias‐free) water splitting by wiring Si|IO‐TiO2|H2ase to a modified BiVO4 photoanode in a photoelectrochemical (PEC) cell during several hours of irradiation. Connecting the Si|IO‐TiO2|H2ase to a photosystem II (PSII) photoanode provides proof of concept for an engineered Z‐scheme that replaces the non‐complementary, natural light absorber photosystem I with a complementary abiotic silicon photocathode. Halbkünstliches Z‐Schema: Eine Photokathode mit hoher Hydrogenase‐Beladung auf p‐Silicium wurde zur Wasserspaltung mit einer BiVO4‐Photoanode gekoppelt. Kombination der Hydrogenase‐Photokathode mit einer Photosystem II‐Photoanode ermöglicht die Wasserspaltung in Tandemzellen mit einem modifizierten Z‐Schema zur verbesserten Solarenergienutzung.