Facile fabrication of porous BiVO₄hollow spheres with improved visible-light photocatalytic properties

Abstract

Bismuth vanadate (BiVO 4 ) hollow spheres with porous structure have been successfully fabricated by a onestep wet solution method with no surfactant and template. The structure, morphologies, and composition of the as-prepared products were studied with X-ray powder diffraction (XRD), transmission electron morphology (TEM), Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS) and UV-vis spectroscopy. Based upon the time-dependent experimental results, BiVO 4 nanospheres with hollow and solid structures can be controlled effectively through the reaction time, and a reasonable formation process was suggested in this work. Moreover, the experiment of degrading methyl orange (MO) under visible-light illumination was conducted to evaluate the photocatalytic performance of the obtained BiVO 4 samples. The porous BiVO 4 hollow spheres exhibit superior visible-light photocatalytic properties for MO degradation than other photocatalysts under irradiation, and could be reused for up to five times without significant reduction in the photocatalytic activity. In addition, based on active group trapping experiments, cOH radicals as the main active species from H 2 O 2 molecules play a vital role in the photocatalytic degradation of MO, and a photocatalytic mechanism for the BiVO 4 system was proposed. High photocatalytic activity, universality and stability suggest that the porous BiVO 4 hollow spheres may have potential applications in wastewater treatment. † Electronic supplementary information (ESI) available: (1) SEM images of BiVO 4 hollow spheres; (2) XPS spectra; (3) SEM images of BiVO 4 solid spheres; (4) XRD patterns; (5) effect of H 2 O 2 amount on photocatalytic degradation rate of MO in the presence of BiVO 4 hollow spheres; (6) PL spectra. SeeFig. 5 (a) Absorption spectra of MO aqueous solutions in the presence of BiVO 4 hollow spheres, (b) degradation rate of MO at different intervals and (c) pseudo-first-order kinetic plots of MO in the presence of various photocatalysts.This journal is

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“…Moreover, nitrogen adsorption-desorption measurements were run as well in order to get further insight into their specific surface area (Figure S3, Supporting Information). Compared with alternative microspheres of similar diameter size, a larger Brunauer-Emmett-Teller (BET) surface area was obtained (i.e., 18.18 m 2 g −1 (Table S1, Supporting Information) vs 8.1-13.8 m 2 g −1 ), [26][27][28] in good agreement with their hierarchical structure and the additional concave defect (Figure 1B). It is known that porous surfaces on BiVO 4 -based structures promote the photogeneration of electron-hole pairs, which in turn improve their photocatalytic properties.…”

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