Modification Of Bismuth Tungstate Catalyst And Its Visible Light Catalytic

Bi₂WO₆has attracted more and more attention due to its unique[Bi₂O₂]²⁺layered structure,and was the most representative oxide in the Aurigillius family.However,the bismuth-based semiconductor photocatalyst has a low photo-generated carrier separation and migration rate,and its photocatalytic activity is inhibited.Based on this,the article used metal ion nickel doping,nano-ZnO composite and the method of magnetizing ZnO/Bi₂WO₆material to modify Bi₂WO₆to improve its photocatalytic performance.The Ni²⁺-doped Bi₂WO₆semiconductor catalytic materials with different molar ratios were successfully prepared by one-step hydrothermal method.The test results show that with the increase of Ni²⁺doping,the activity of Ni²⁺/Bi₂WO₆catalyst increases first and then decreases.The sample with molar ratio n（Ni）:n（Bi）=0.25%has the highest catalytic activity.Under visible light irradiation,the degradation rate of the catalyst to the Rh B solution increased by 30%.Cycle 5 times at the same time,and its photocatalytic performance won’t significantly decrease.In the photocatalytic reaction of the modified catalyst,superoxide radical（.O₂^-）is the main active species.Phase characterization shows that Ni ions will not change the crystal structure of Bi₂WO₆,but will expand the Bi₂WO₆lattice;Ni²⁺doped Bi₂WO₆photocatalytic material will act as an electron capture center in the crystal.At the same time,the photoelectric performance test shows that after modification The instantaneous photocurrent density of the catalyst was three times that of the single phase,which promotes the separation of photogenerated carriers,so that Bi₂WO₆exhibits excellent photocatalytic performance.The ZnO/Bi₂WO₆photocatalysts with different loadings were prepared by the precipitation-solvothermal method,and a series of characterizations were performed on them.The results as follows:the ZnO composite catalyst has a slight change in morphology compared to the pure phase Bi₂WO₆.When the molar ratio of ZnO to Bi₂WO₆was 20%,its catalytic performance was the best.Under visible light,the degradation rate of Rh B is catalytically degraded,and the degradation rate of ZnO/Bi₂WO₆was 35%higher than that of single Bi₂WO₆.The photoelectric performance test results showed that the photocurrent density of the composite catalyst was about 8 times that of the pure phase,which greatly improved the photocatalytic performance.To make the composite catalyst can be recycled.In this paper,the ZnO/Bi₂WO₆composite was magnetized to prepare a composite nano-ZnO/Bi₂WO₆magnetic catalyst.This N-P-N heterojunction structure was beneficial to inhibit the recombination of photo-generated electron and hole pairs,thereby improved the photocatalytic activity of the composite catalyst.At the same time,the magnetic properties of the composite were tested,and the results showed that the three-phase magnetic material has greater coercivity.After five cycles of stability testing,the composite catalyst still maintained excellent photocatalytic and magnetic properties.