Printable Photocatalyst Sheets Incorporating a Transparent Conductive Mediator for Z-Scheme Water Splitting

Efficient and scalable sunlight-driven water-splitting systems are essential for practical renewable hydrogen production. Particulate photocatalyst sheets for Z-scheme water splitting can be printed at low cost using inks containing a hydrogen evolution photocatalyst (HEP), an oxygen evolution photocatalyst (OEP), and conductive metal nanoparticles, and can be applied to large areas. However, the metal nanoparticles lead to backward reactions and light absorption. Herein, we demonstrate printable photocatalyst sheets composed of SrTiO3: La, Rh as the HEP, BiVO4: Mo as the OEP, and nanoparticulate indium tin oxide as a transparent and electrochemically inert conductor, for efficient pure-water splitting. The photocatalyst sheets decompose water with a solar-to-hydrogen energy conversion efficiency of 0.4%, which is one of the highest values among Z-scheme overall water-splitting systems prepared without the requirement for a vacuum process. Printable and efficient photocatalyst sheets obtained using cost-effective and readily extensible procedures spread opportunities toward practical solar hydrogen production via the water-splitting reaction.