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Enhancing photocatalytic activity by tuning the ratio of hexagonal and orthorhombic phase Nb₂O₅ hollow fibers

Shao, Ruyi, Cao, Zhenzhu, Xiao, Yang, Dong, Hongjie, He, Weiyan, Gao, Yanfang, Liu, Jinrong
RSC advances 2014 v.4 no.50 pp. 26447-26451
X-ray diffraction, absorption, adsorption, aqueous solutions, cotton, methylene blue, photocatalysis, photocatalysts, reflectance spectroscopy, scanning electron microscopy, surface area, ultraviolet radiation
Cotton was used as template for the fabrication of a biomorphic Nb₂O₅ photocatalyst with hexagonal and orthorhombic structures. The as-prepared Nb₂O₅ was characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), specific surface area and UV-Vis diffused reflectance spectra measurements. The photocatalytic activity of the Nb₂O₅ fibers was evaluated through degradation of methylene blue (MB) in aqueous solution exposed to UV light. SEM results show that biomorphic Nb₂O₅ fibers are both hollow and have porous walls. The architectures allow a more accessible surface for the photocatalytic decomposition of dyes molecules. The photocatalytic activity of physically mixed fibers with 75% H-Nb₂O₅ and 25% O-Nb₂O₅ phases is superior to those of pure H- and O-Nb₂O₅ phases, and other samples with different H- and O-Nb₂O₅ ratios. Such superior photocatalytic activity is mainly due to an optimal balance between the adsorption of MB and the absorption of UV light. Moreover, the large size of the Nb₂O₅ hollow fibers allows them to be easily separated from the solution.