Synthesis Of Silver Vanadate-base Photocatalyst And Investigation On Their Photocatalytic Performance

In this article,focusing on silver vanadate?Ag₃VO₄?based materials,we investigated the methods to improve their photocatalytic properties and photocatalytic ability.The possible reaction mechanism was proposed through both experiments and theoretical calculations,our main works were summaried as follows:?1?The Ag₃VO₄ and a series of Ag₂O/Ag₃VO₄ photocatalysts were synthesized by adjusting the molar ratio of silver-vanadium?Ag-V?via the ultrasonic-assisted technology.The photocatalytic activity of Ag₂O/Ag₃VO₄ under visible light irradiation was evaluated using methyl orange?MO?as a template.The results show that compared to pure Ag₃VO₄,the as-synthesized composite Ag₂O/Ag₃VO₄ gave rise to a significantly higher photocatalytic activity.In particular,the3Ag₂O/2Ag₃VO₄ with Ag:V of 6:1 can degrade the MO about 85%within 60 min under visible light irridation.Compared with the reported literature,the effect is best.The enhanced photocatalytic performance was attributed to the composite formed between Ag₂O and Ag₃VO₄,improving the separation efficiency of the photogenerated electron-hole?e^--h⁺?.?2?Ultrasound-assisted method was used to successfully synthesize g-C₃N₄/Ag₃VO₄ nanocomposites with different mass ratios.Compared with pure phase g-C₃N₄ and Ag₃VO₄,the degradation of tetracycline?TC?over the composite samples under visible light irradiation was obviously improved.Especially,the 5%g-C₃N₄/Ag₃VO₄ nanocomposite had the best performance and the degradation rate of tetracycline was close to 80%within 40 min.Based on the results of the active species testing,we proposed a possible reaction mechanism,in which the enhanced photocatalytic performance was attributed to the composite formed by g-C₃N₄ and Ag₃VO₄,improving the separation efficiency of photogenerated charges.?3?Based on the density functional theory?DFT?,we calculated and discussed the effects of different concentrations of Nb,Ta doping on the electronic structure of Ag₃VO₄.In this work,for the doping of Nb⁵⁺ions models,the total energy was decreased with the increase of the doping concentration.Meanwhile,the doping is easy to form by investigating the formation energy.Thus,the system tends to be stable.Moreover,after doping,the position of the conduction band shifted up to the highly energy level and the band gap was increased,but there is a good response to visible light.For the doping models of Ta⁵⁺ions,the total energy of the system was risen with the increase of the doping concentration.It was found is not easy for Nb⁵⁺ion doping into the cell of Ag₃VO₄.The position of the conduction band moves upward when doping concentration is 12.5%.Therefore,the band gap was increased,but there is a good response to visible light.On the contrary,for 25%and37.5%doping of Ta⁵⁺ions,the conduction band positions were decreased.Consequently,the band gap was decreased and the optical response range was largerly increased.