Solar Water Splitting with a Hydrogenase Integrated in Photoelectrochemical Tandem Cells

Abstract

Abstract Hydrogenases (H 2 ases) are benchmark electrocatalysts for H 2 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 H 2 ase through the introduction of a hierarchical inverse opal (IO) TiO 2 interlayer. This proton‐reducing Si|IO‐TiO 2 |H 2 ase photocathode is capable of driving overall water splitting in combination with a photoanode. We demonstrate unassisted (bias‐free) water splitting by wiring Si|IO‐TiO 2 |H 2 ase to a modified BiVO 4 photoanode in a photoelectrochemical (PEC) cell during several hours of irradiation. Connecting the Si|IO‐TiO 2 |H 2 ase 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.