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

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.