Combination of a sulphide semiconductor and an electroactive enzyme: a path for visible light-induced water photo-splitting

Abstract

Solar fuel generation is an actively researched subject, as it may facilitate a renewable energy¿based economy. Several semiconductors have been proposed as light absorbers for this purpose; the best known one, TiO2, is very active, stable and inexpensive, but only converts UV light. Some sulphides like In2S3 and SnS2, with bandgaps of respectively 2.0 and 2.2 eV, have shown better photo¿activity with visible light (using efficiently photons in their whole absorption range) and stability against corrosion (in oxidative abatement of organics) than e.g. the toxic compound CdS. Here we will describe our recent results on the photocatalytic production of H2 in aqueous suspension using a combination of a Ni¿Fe hydrogenase enzyme (no precious or heavy metal involved) and In2S3, and will report new results on the photon¿assisted (at lower potentials than in the dark) electrochemical generation of O2 using an electrode containing In2S3 as light absorber and a Cu¿based laccase enzyme anchored to it which acts as molecular catalyst for O2 evolution from water with good faradaic efficiency.