Synthesis of novel Au@Void@Nb₂O₅ core-shell nanocomposites with enhanced photocatalytic activity

Nb₂O₅ as a semiconductor material has attracted significant attention in recent years due to its outstanding advantages. In this article, novel Au@Void@Nb₂O₅ core-shell nanocomposites have been fabricated through a facile sol-gel method. The construction process of this core-shell nanostructure has been presented in detail. The as-prepared core-shell nanostructure exhibits nanosphere morphology with Nb₂O₅ acting as the shell and Au nanoparticles acting as the core, which was proved using SEM and TEM. The noble metal Au core protected by the Nb₂O₅ shell promotes an interfacial charge-transfer process. The core-shell nanocomposites demonstrate excellent visible light absorption, as shown by the UV-Vis diffuse reflectance spectra. The as-prepared photocatalyst Au@Void@Nb₂O₅-2 calcined at 300 °C exhibits higher photocatalytic efficiency than Au@SiO₂@Nb₂O₅-2-300 °C, Nb₂O₅ and P25, as evaluated by the degradation of rhodamine B (Rh B) under visible light. In the photodegradation process of the Rh B solution, holes (h+) play a more important role than hydroxyl radicals (˙OH) over the as-prepared photocatalyst, which was analyzed using active species trapping experiments and photoluminescence (PL) spectroscopy. Moreover, the photocatalyst Au@Void@Nb₂O₅-2 calcined at 300 °C exhibits excellent durability of its photocatalytic activity even after five successive cycles. This contribution gives a new perspective for designing and preparing novel metal-Nb₂O₅ nanostructure catalysts applied in environmental treatments.