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.