Enhancing Photocatalytic Hydrogen Production with Nanocone-Structured Z-Scheme Photocatalysts

Z-scheme photocatalysts have emerged as a promising solution to address the efficiency challenges in solar-assisted water splitting, thanks to their capability to efficiently absorb visible light and maintain the essential charge potential required for overall water splitting. To ensure the successful operation of Z-scheme photocatalysts, it is crucial that the two constituent photocatalysts and the charge recombination layer are precisely arranged in a specific sequential order. However, previous research has predominantly utilized Z-scheme photocatalysts in a randomly mixed configuration, thereby preventing the full exploitation of the unique attributes inherent to Z-scheme photocatalysts.<br/> <br/>This study demonstrates fabrication of a nanocone-structured BiVO4/SrTiO3 Z-scheme photocatalytic thin film, enabling effective Z-scheme charge transfer. The fabrication process involves the preparation of a nanocone BiVO4 structure on a glass substrate, the formation of a BiVO4/reduced graphene oxide (RGO) composite nanocone structure, and the deposition of SrTiO3 nanoparticles to form BiVO4-RGO-SrTiO3 Z-scheme photocatalyst. The resulting structure comprises BiVO4, RGO, and SrTiO3 arranged sequentially. A comparative analysis between randomly mixed Z-scheme photocatalysts and the arranged Z-scheme photocatalyst demonstrates a significant enhancement in hydrogen production efficiency for the latter, underscoring the pivotal role of precise arrangement in Z-scheme photocatalysis.<br/> <br/>Additionally, the study investigates how the superhydrophobic surface properties of the nanocone structure influence the capture of hydrogen and oxygen gas bubbles generated during the water splitting reaction in photocatalyst module. The nanocone-structured Z-scheme thin film efficiently captures gas bubbles due to its superhydrophobic surface characteristics, while the randomly mixed Z-scheme photocatalyst experiences reduced gas bubble detachment, resulting in decreased photocatalyst production efficiency.<br/> <br/>This study underscores the importance of meticulous Z-scheme photocatalyst arrangement and highlights the advantages of the nanocone structure in improving gas bubble capture during the water splitting process, thus contributing to the advancement of photocatalytic hydrogen production.