Synergistic Effects of Morphology and Interface Engineering in WO₃/TiO₂ for Photocatalytic Hydrogen Generation

Developing efficient catalysts for H₂ release is significant in advancing sustainable energy systems. In particular, heterostructures based on WO₃ and TiO₂ stand out as promising photocatalysts owing to their tunable band structures, robust stability, and cost-effectiveness. This study investigates the impact of morphology and synthesis approach on the catalytic performance of WO₃/TiO₂ heterostructures for ammonia borane dehydrogenation. Two synthesis approaches, ex situ coupling of pre-synthesized WO₃ with TiO₂ and in situ growth of TiO₂ on WO₃, were systematically utilized to tailor the heterointerface and morphology. Controlled reaction conditions facilitated the formation of hexagonal-like WO₃, thereby enabling the growth of distinct nanostructures. When integrated with TiO₂, the morphology, heterojunction characteristics, and surface area were found to be highly dependent on the synthesis method. The in situ WO₃/TiO₂ heterostructure (∼0.302 µmol min^-1) exhibited superior catalytic performance compared to ex situ method (∼0.258 µmol min^-1). This enhancement is ascribed to the synergistic effects of increased surface area (21.81 m²g^-1 for in situ sample compared with 11.33 m²g^-1 for ex situ sample) and a more intimate heterointerface, which together promote effective charge separation and electron transfer. The findings highlight that not only morphology and composition but also the synthetic route play a critical role in determining catalytic efficiency.