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

Cotton was used as template for the fabrication of a biomorphic Nb O photocatalyst with hexagonal and orthorhombic structures. The as-prepared NbO 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 NbO fibers was evaluated through degradation of methylene blue (MB) in aqueous solution exposed to UV light. SEM results show that biomorphic NbO 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-Nb O and 25% O-NbO phases is superior to those of pure H- and O-NbO phases, and other samples with different H- and O-NbO 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 NbO hollow fibers allows them to be easily separated from the solution. © 2014 the Partner Organisations.