Construction of novel step-scheme TiO2-WO3 nanostructured heterojunction towards morphology-driven enhancement of photocatalytic hydrogen evolution

Abstract

Photocatalytic hydrogen evolution driven via solar energy is an efficient and sustainable method for hydrogen synthesis. The use of titania (TiO₂), an efficient photocatalyst in hydrogen generation, can be improved further by reducing the recombination rate of photoinduced charge carriers. In this context, WO₃ is a viable material to boost TiO₂ photoefficiency. In the present study, 1D TiO₂ nanotube/WO₃ nanorod (TN-WR) Step-scheme (S-scheme) heterojunction was fabricated via a facile impregnation method. XRD studies confirmed the anatase phase of TiO₂ and the monoclinic phase of WO₃. Morphological studies revealed the 1D microstructure of the nanocomposite with a mesoporous surface. UV-DRS and PL profiles displayed a bathochromic shift in wavelength signifying the activation of the nanocomposite in the visible region. XPS studies indicated the generation of defective sites in TiO₂ upon incorporation of WO₃. Thus, the novel 1D TN-WR S-scheme heterojunction nanocomposite demonstrates a remarkably high photocatalytic hydrogen generation rate of 1761 μmol g⁻¹h⁻¹. In order to investigate the role of morphology in hydrogen evolution, TiO₂/WO₃ nanocomposites with spherical morphologies were considered for comparison. This study provides a novel insight into the design of semiconductor heterojunction photocatalysts for efficient hydrogen evolution while avoiding the use of noble metals.