Photoelectrochemical H 2 Evolution with a Hydrogenase Immobilized on a TiO 2 ‐Protected Silicon Electrode

The combination of enzymes with semiconductors enables the photoelectrochemical characterization of electron‐transfer processes at highly active and well‐defined catalytic sites on a light‐harvesting electrode surface. Herein, we report the integration of a hydrogenase on a TiO 2 ‐coated p‐Si photocathode for the photo‐reduction of protons to H 2 . The immobilized hydrogenase exhibits activity on Si attributable to a bifunctional TiO 2 layer, which protects the Si electrode from oxidation and acts as a biocompatible support layer for the productive adsorption of the enzyme. The p‐Si|TiO 2 |hydrogenase photocathode displays visible‐light driven production of H 2 at an energy‐storing, positive electrochemical potential and an essentially quantitative faradaic efficiency. We have thus established a widely applicable platform to wire redox enzymes in an active configuration on a p‐type semiconductor photocathode through the engineering of the enzyme–materials interface.