Synthesis Of Ag₃VO₄and Its Visible-Light Photocatalytic Performance

In this paper, Ag₃VO₄photocatalyst materials were successfully prepared bymicrowave, reverse microemulsion and refluxing method, and the photocatalyticproperties of the product were also studied, respectively. The main content can besummarized as follows:Using ammonium metavanadate （NH₄VO₃） and silver nitrate （AgNO₃） asstarting materials, Ag₃VO₄powders were synthesized by microwave method. Thecrystal structures, morphologies, specific surface area, particle size distribution andoptical properties of the as-prepared samples were characterized by means of XRD,SEM, BET, LLS, UV-Vis techniques. A35W Xe lamp was used as light source toinvestigate the photocatalytic activity of Ag₃VO₄for the degradation of rhodamine B.The results shows that the pH value have a great effect on the composition of thesamples. When the pH value of the NH₄VO₃solution is14, the as-prepared samplesbelong to monoclinic phase Ag₃VO₄. When the reaction solutions are heated for4minwith the microwave firepower of20%, the specific surface area of the as-obtainedsamples with particle diameters of100―200nm is10.5m2·g^-1. UV-Vis analysisexhibits that Ag₃VO₄has a strong and wide absorption peak at the wavelength regionof420―650nm, therefore, it has strong absorption for visible light, and the energyband gaps is1.90eV. Photocatalytic tests indicate that the samples as-prepared bymicrowave method exhibit a higher visible-light photocatalytic activity than that ofcommeracial P25TiO₂, and under the microwave firepower of20%, the as-preparedAg₃VO₄with microwave heating for4min has the highest visible-light photocatalyticactivity in all samples of different microwave heating time. The degradation rate ofrhodamine B is up to98.6%after160min degradation under35W Xe lampirradiation. In addition, Ag₃VO₄have high stability in the process of photocatalysis.Using NH₄VO₃and AgNO₃as starting materials, via NaOH adjusting pH valueof the NH₄VO₃solution to14, Ag₃VO₄powders were synthesized by reversemicroemulsion method. The samples were characterized by XRD, SEM and UV-Vismeans. The effects of different conditions such as ω0value, reaction time and reactantconcentration on the morphology and size of the samples were studied. Photocatalyticperformance of the Ag₃VO₄was investigated by measuring the decomposition rate ofrhodamine B. The results show that the prepared sample is monoclinic phase Ag₃VO₄. It is also demonstrated that the ω0and reactant concentration have a significant effecton the morphology and size of the final samples. The photodegradation resultsindicate that as-prepared samples have high stability and photocatalytic activity. Theas-prepared samples have a higher visible-light photocatalytic activity than that ofcommeracial P25TiO₂. When AgNO₃solution concentration is0.6mol·L^-1, thesample synthesized at50°C for1h has a highest visible-light photocatalytic activityin all samples, and the degradation rate of rhodamine B reach96.7%afterillumination for100min under35W Xenon Lamp. UV-Vis analysis indicates thatAg₃VO₄has a strong and wide absorption peak at the wavelength region of410―580nm and its band gap is around1.86eV.Using NH₄VO₃and AgNO₃as starting materials, through adjusting pH value ofthe reaction mixture to7, Ag₃VO₄powders were synthesized by liquid-phase directprecipitation method. The phases, structures, morpholgies and optical properties ofthe samples were observed by XRD, SEM and UV-Vis. The visible light was used aslight source to investigate the photocatalytic activity of Ag₃VO₄for the degradation ofrhodamine B solution. The results show that the as-prepared sample is monoclinicphase Ag₃VO₄. It is also demonstrated that the composition of the samples areimportantly influenced by pH value of the reaction mixture, and the size andmorphology of the silver vanadate are large influenced by reaction time, reactiontemperature and surfactant. UV-Vis result indicates that Ag₃VO₄has a strong andwide absorption peak at the wavelength region of450―800nm, and its band gap is1.88eV. The photodegradation results indicate that as-prepared samples have a highervisible-light photocatalytic activity than that of commeracial P25TiO₂. The sampleobtained at80℃for8h could decolorize rhodamine B solution well and thedegradation rate of rhodamine B is up to97.7%after illuminating for100min under35W Xenon Lamp.