WO₃/BP/g-C₃N₄ –based cauliflower nanocomposite fabricated by pulsed laser ablation for overall water splitting

Fast recombination of photoinduced charge carriers due to poor charge separation are the fundamental challenges of particulate photocatalysis. One of the key solutions to mitigate these problems is the construction of heterojunction nanocomposites. In this study, we present a heterojunction composing of tungsten oxide/ black phosphorous and graphitic nitride (WO₃/BP/g-C₃N₄) fabricated via pulsed laser ablation in liquid. To highlights the synergistic role of the fabricated components, the following photocatalysts were also prepared, WO₃, WO₃/BP, and g-C₃N₄. The overall photocatalytic production of hydrogen was examined for WO₃, WO₃/BP, g-C₃N_4, and WO₃/BP/g-C₃N₄. There was no detectable production of hydrogen gas for the WO₃ and g-C₃N₄. However, the hydrogen production rate was approximately 75 µmolg⁻¹h⁻¹ for the WO₃/BP. The production rate substantially increased to 400 µmolg⁻¹h⁻¹ for the WO₃/BP/g-C₃N₄ photocatalyst. The enhancement can be attributed to the cumulative increase in the UV–visible light absorption, mainly by BP and partially g-C₃N₄ in the fabricated WO₃/BP/g-C₃N_4, as well as the effective charge transport leading to separation of charge carriers which is well explained using the Z-scheme mechanism. Moreover, the WO₃/BP/g-C₃N₄ composite catalysts produced stable and consistent results after a prolonged operation which indicates the reusability of the photocatalyst.