Superstructure Ta2O5 mesocrystals derived from (NH4)2Ta2O3F6 mesocrystals with efficient photocatalytic activity

Abstract

Superstructured mesocrystalline Ta₂O₅ nanosheets were successfully prepared from mesocrystalline (NH₄)₂Ta₂O₃F₆ nanorods by the annealing method for the first time. The as-prepared mesocrystalline Ta₂O₅ nanosheets in this work showed remarkable visible light absorption, mainly due to the formation of oxygen vacancy defects in the mesocrystalline Ta₂O₅ nanosheets, which was also confirmed by XPS spectra, Raman spectra and EPR spectra. Besides, the mesocrystalline Ta₂O₅ nanosheets showed a highly enhanced photocatalytic activity of 11 268.24 μmol g⁻¹ h⁻¹, about 3.95 times that of commercial Ta₂O₅. Moreover, the specific surface area of the mesocrystalline Ta₂O₅-800 nanosheets was 16.34 m² g⁻¹, about 5.32 times that of the commercial Ta₂O₅ (3.072 m² g⁻¹). The valence band XPS spectra indicated a strong oxidizing ability of the mesocrystalline Ta₂O₅ nanosheets in comparison to that of commercial Ta₂O₅. The formation of superstructured Ta₂O₅ mesocrystals generated long lifetime carriers and effective conduction pathways, which greatly enhanced the photocatalytic activity for hydrogen production.