A TiO2 Nanoparticle System for Sacrificial Solar H2 Production Prepared by Rational Combination of a Hydrogenase with a Ruthenium Photosensitizer

A hybrid system comprising a hydrogenase and a photosensitizer co-attached to a nanoparticle serves as a rational model for fast dihydrogen (H₂ ) production using visible light. This chapter describes a stepwise procedure for preparing TiO₂ nanoparticles functionalized with a hydrogenase from Desulfomicrobium baculatum (Db [NiFeSe]-H) and a tris(bipyridyl)ruthenium photosensitizer (RuP). Upon irradiation with visible light, these particles produce H₂ from neutral water at room temperature in the presence of a sacrificial electron donor – a test-system for the cathodic half reaction of water splitting. In particular, we describe how a hydrogenase and a photosensitizer with desired properties, including strong adsorption on TiO₂ , can be selected by electrochemical methods. The catalyst Db [NiFeSe]-H is selected for its high H₂ production activity even when H₂ and traces of O₂ are present. Adsorption of Db [NiFeSe]-H and RuP on TiO₂ electrodes results in high electrochemical and photocatalytic activities that translate into nanoparticles exhibiting efficient light harvesting, charge separation, and sacrificial H₂ generation.