Morphology and crystal facet-dependent activation mechanism of persulfate by V2O5 nanomaterials for organic pollutants degradation

Vanadium pentoxide (V2O5) including nanorod-like V2O5 (V-R), nanowire-like V2O5 (V-S) and nanospheres (V-S) were synthesized by simple hydrothermal methods and then used as heterogeneous catalysts for persulfate activation. A series of characterization containing XRD, XPS, SEM, TEM and BET tests confirmed the different exposed crystal facets, morphologies and specific surface areas for the three kinds of V2O5 catalysts. The experimental results demonstrated that the combination of persulfate with V2O5 was efficient in promoting the degradation of acid orange 7 (AO7). The three types of V2O5 exhibited different abilities to activate persulfate (PS) for AO7 degradation with a sequence of V-W > V-S > V-R, which is probably caused by the larger specific surface area (similar to 30.428 m(2) g(-1)) and the exposed crystal facet (111) with lower Fermi energy and higher positive charge densities for V-W. Free radical quenching and ESR studies revealed that both sulfate radical (SO4-center dot) and hydroxyl radical ((OH)-O-center dot) contributed to AO7 degradation. Furthermore, the prepared catalysts exhibited excellent recyclability and stability.