Photocatalytic water splitting using particulate semiconductors is a potentially scalable and economically feasible technology for converting solar energy into hydrogen. Z-scheme systems based on two-step photoexcitation of a hydrogen evolution photocatalyst (HEP) and an oxygen evolution photocatalyst (OEP) are suited to harvesting of sunlight because semiconductors with either water reduction or oxidation activity can be applied to the water splitting reaction. However, it is challenging to achieve efficient transfer of electrons between HEP and OEP particles. Here, we present photocatalyst sheets based on La- and Rh-codoped SrTiO3 (SrTiO3:La, Rh; ref. ) and Mo-doped BiVO4 (BiVO4:Mo) powders embedded into a gold (Au) layer. Enhancement of the electron relay by annealing and suppression of undesirable reactions through surface modification allow pure water (pH 6.8) splitting with a solar-to-hydrogen energy conversion efficiency of 1.1% and an apparent quantum yield of over 30% at 419 nm. The photocatalyst sheet design enables efficient and scalable water splitting using particulate semiconductors.

Synthesis of nanostructured BaTaO 2 N thin films on metallic Ta substrates, and their application as photoanodes for solardriven photoelectrochemical water oxidation were studied. Ba 5 Ta 4 O 15 nanosheets vertically grown on Ta substrates by a hydrothermal process were converted into perovskite BaTaO 2 N with a branching nanostructure by thermal nitridation under an ammonia gas flow. The crystal quality and photoelectrochemical properties of the BaTaO 2 N thin films were found to improve with increasing nitridation temperature up to 1000 °C. A Ta 4 N 5 interfacial layer was formed between the BaTaO 2 N thin film and the Ta substrate. Under simulated AM 1.5G light, the BaTaO 2 N electrode generated a photoanodic current, although it rapidly decreased due to photooxidative corrosion. The degradation of the BaTaO 2 N electrode could be alleviated by the deposition of a cobalt phosphate layer on its surface. The modified electrode maintained a photoanodic current of 0.75 mA cm −2 at 1.23 V versus the reversible hydrogen electrode with a Faradaic efficiency of almost unity.

Controlled layered structures fabricated by thin film transfer enhance the photoelectrochemical water splitting on Ta3N5 photoanodes.

A Ta3N5photoanode incorporating a Nb4N5interlayer exhibits an oriented Ta3N5grain layer and an enhanced photocurrent for water splitting.