Z‐Scheme Water Splitting under Near‐Ambient Pressure using a Zirconium Oxide Coating on Printable Photocatalyst Sheets

Sunlight‐driven water splitting systems operating under ambient pressure are essential for practical renewable hydrogen production. Printable photocatalyst sheets, composed of a hydrogen evolution photocatalyst (HEP), an oxygen evolution photocatalyst (OEP), and conductive metal nanoparticles, are cost‐effective and scalable systems. However, the decrease in water splitting activity under ambient pressure due to reverse reactions hampers their practical application. In this study, coating zirconium oxide (ZrOx) by facile drop‐casting onto a printed photocatalyst sheet, which consists of SrTiO3 : Rh, BiVO4 : Mo, and Au nanocolloids as the HEP, OEP, and electron mediator, respectively, effectively maintains the water splitting activity at elevated pressure. The ZrOx‐coated photocatalyst sheet retains 90 % and 84 % of the base performance (the pristine sheet at 10 kPa) at 50 and 90 kPa, respectively. Achieving efficient water splitting at the ambient pressure by inexpensive and extensible processes is an important step toward solar hydrogen production. Prints and the new power generation: Sunlight‐driven water splitting systems operating under ambient pressure are essential for practical renewable hydrogen production. Printable photocatalyst sheets composed of a hydrogen evolution photocatalyst, an oxygen evolution photocatalyst, and conductive metal nanoparticles, are cost‐effective and scalable systems. Coating zirconium oxide onto a printed photocatalyst sheet effectively suppresses reverse reactions and maintains the water splitting activity at near‐ambient pressure.