Synthesis And Visible-light-driven Photocatalytic Performance Of Modified AgVO₃ Nanomaterials

Driven by inexhaustible sunlight,semiconductor photocatalytic technology can make degrading organic pollutants,splitting water into oxygen and hydrogen,reducing carbon dioxide and other reactions possible.It provides a new way to solve environmental pollution problems and alleviate fossil energy crisis.AgVO3 with a narrow band gap(about 2.3 e V)is a new type of promising semiconductor photocatalyst.It has good visible light response and stability,but the relatively high photo-induced electrons and holes recombination efficiency seriously inhibits its photocatalytic performance in degrading organic pollutants.In this paper,AgVO3 was modified by coupling with other semiconductor or doping with rare earth elements cation in order to synthesis AgVO3-based photocatalysts with high activity.The specific research results are as follows:One-dimensional AgVO3 nanowires with smooth surface were synthesized by hydrothermal method.Ag2 Cr O4 nanoparticles were anchored on the surface of AgVO3 nanowires by deposition precipitation to synthesis Ag2 Cr O4/AgVO3 hybrid catalyst.Introducing Ag2 Cr O4 broadened the light absorption range of AgVO3 which improved the utilization of sunlight,and the formation of heterojunction facilitated the separation of photo-generated electrons and holes.The photocatalytic activity of composites was related to the loading content of Ag2 Cr O4.When the mass ratio of Ag2 Cr O4 to AgVO3 was 0.2:1,the heterojunction photocatalyst exhibited the best activity,where the apparent reaction rate constant for degradation of rhodamine B under visible light irradiation was 22.4 times that of pure AgVO3.The improvement is mainly ascribed to that the formation of heterojunction accelerated the separation of charge carriers.Superoxide radicals and hydroxyl radicals were the predominant active species in the catalytic reaction,a mechanism of enhanced photocatalytic performance was proposed on the base of experimental results.One-dimensional rare earth elements doping-AgVO3 nanowires(RE = Lu,Yb,Eu,Pr,Tb,Tm)were prepared by one-step hydrothermal method.Rare earth doping did not alter the nanowires morphology of AgVO3.The rare earth cations inserted into AgVO3 crystal lattice and restricted the growth of the nanowires.Fine nanowires with a diameter of less than 100 nm increased the specific surface area of the material.Rare earth doping improved the capacity of adsorbing dye molecules,narrowed the band gap,increased the absorption intensity in visible light region,and restricted the recombination of photogenerated electrons and holes.All the above factors made the rare earth doped AgVO3 nanowires exhibited higher photocatalytic performance than the pure one when degrading rhodamine B under visible light irradiation.The influence of doping dosages of Pr,Tb and Tm on the catalytic performance of AgVO3 displayed a similar trend.With the increase of the doping dosage,the catalytic activity became better first.When the doping amount was up to 0.5% the activity became the best,and then decreased as the amount of doping cations continued to increase.0.5% Tm-AgVO3 exhibited the best for degradation of rhodamine B under visible light irradiation,whose rate was 6.5 times that of singlephase AgVO3.