Synthesis And Visible-light Photocatalytic Activity Of ?-AgVO₃ Nanowire Composites

One dimensional ?-AgVO₃ nanowire has gained widespread attention because of its narrow band gap,visible light response,large surface area and good crystallization.In this paper,we chose one-dimensional ?-AgVO₃ nanowires as the substrate materials to prepare Ag₃VO₄/?-AgVO₃ and Ag₂CO₃/?-AgVO₃ composites through chemical precipitation approach and icon exchange method,respectively,which could improve the photocatalytic performance of ?-AgVO₃ under visible-light illumination.The phase compositions,microstructures,binding ernergies,crystallization,optical properties,superficial areas and charge separation of the composite photocatalysts were systematically characterized via powder X-ray diffraction,scanning electron microscopy,high-resolution transmission electron microscopy,UV-Vis diffuse reflection spectroscopy,BET measurement,X-ray photoelectron spectroscopy,and photoluminescence spectroscopy.In the paper,different molar ratios of Ag₃VO₄/?-AgVO₃ heterojunction were successfully fabricated by chemical precipitation and hydrothermal method.Compared with single-phase Ag₃VO₄ and ?-AgVO₃ nanowires,all Ag₃VO₄/?-AgVO₃ nanowires composite photocatalysts displayed much higher photocatalytic activity for rhodamine B?RhB?degradation under visible-light irradiation.The sample with a molar ratio of 30% Ag₃VO₄ to ?-AgVO₃ showed the highest photocatalytic activity for RhB degradation,which was almost 9 and 2.4 times higher than those of pure ?-AgVO₃ and Ag₃VO₄.The Ag₃VO₄/?-AgVO₃ heterojunction can separate photogenerated electrons and holes efficiently.In addition,the holes and hydroxyl radicals play significant roles in the photocatalytic degradation of RhB under visible light.In this study,different molar ratios of Ag₂CO₃/?-AgVO₃ nanocomposites were prepared by a facile ion-exchange approach.It is found that all Ag₂CO₃/?-AgVO₃ nanowires composite photocatalysts exhibited much higher photocatalytic activity compared with pure Ag₂CO₃ and ?-AgVO₃ for RhB degradation under visible-light irradiation.The optimal mass ratio of Ag₂CO₃ to ?-AgVO₃ content for the RhB photodegradation activity of the composite structures was determined.In particular,the photocatalytic activity of the 40% Ag₂CO₃/?-AgVO₃ nanowires composite for the degradation of RhB was almost 13.3 and 3.6 times higher than those of ?-AgVO₃ nanowires and Ag₂CO₃,respectively.The photoluminescence spectroscopy proved that the Ag₂CO₃/?-AgVO₃ heterojunction can separate photogenerated electrons and holes efficiently.Furthermore,the trapping experiments also confirmed that hole is the major active species for RhB degradation under visible light.