Patterning alternate TiO2 and Cu2O strips on a conductive substrate as film photocatalyst for Z-scheme photocatalytic water splitting

Abstract

Semiconductor heterostructures mediated by electrical conductors are very promising for Z-scheme photocatalytic water splitting. In contrast to conventional particulate heterostructures, alternate TiO₂ and Cu₂O film stripes patterned parallel on a fluorine-doped tin oxide (FTO) conductive substrate was fabricated as a model film photocatalyst to study the characteristics of the photogenerated charge transfer process. The Z-scheme transfer process with an effective transport distance of up to 5 μm occurs only in regions distant from the TiO₂/Cu₂O strip edges through the FTO substrate from the bottom. In contrast, the transfer of charge around their contact regions follows the conventional transfer process through the TiO₂/Cu₂O strip interface. These results indicate that the Z-scheme transfer process occurring in such a large region dominates the charge transfer processes in the TiO₂/FTO/Cu₂O pattern film heterostructure. Importantly, unlike the single component film, which is inactive for photocatalytic overall water splitting, the modified TiO₂/Cu₂O pattern film can induce photocatalytic overall water splitting at a stoichiometric H₂/O₂ ratio close to 2:1. These findings have significant implications in designing efficient heterostructures by employing a Z-scheme charge transfer process.

Keywords: Heterostructure; Pattern film; Photocatalyst; Water splitting; Z-scheme.