Design of a Z-scheme printable artificial leaf device based on CdS@TiO 2 /Pt/ITO/WO 3 @Co 3 O 4 for water splitting

Hydrogen and oxygen production based on photocatalytic monolithic water splitting is considered to be one of the effective ways to produce sustainable and clean energy. The key challenge in this process is to develop new photocatalysts that can simultaneously produce H 2 and O 2 at a stoichiometric ratio of 2:1 without the use of any sacrificial agents. In order to solve this problem, highly efficient and ingenious photosystems in nature have been studied intensively. Herein, we prepared printable Z-type composite photocatalysts CdS@TiO 2 /Pt/ITO/WO 3 /Co 3 O 4 mimicking biological vegetative leaves in nature and constructed an “artificial leaf” device that completely decomposes water. We use an electron solid penetrating transporter ITO, which can rapidly transfer photogenerated electrons and photogenerated holes and reduce the compound rate of photogenerated carriers. Thus, the efficiency of photocatalytic total water dissolution is enhanced. This photocatalyst was able to produce both H 2 and O 2 in water with an H 2 production rate of 75.93 μmol g −1 h −1 and an O 2 production rate of 36.49 μmol g −1 h −1 . We designed the oxygen-producing photocatalyst WO 3 /Co 3 O 4 , which produced oxygen at a rate of 159.21 μmol g −1 h −1 6 times higher than that of WO 3 alone. Furthermore, the morphology, composition, and microstructures of the photocatalyst were characterized by field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and nitrogen adsorption–desorption.