Photocatalytic Performance Of Annealed ZnO And Reflux Prepared Bismuth Molybdate

This work mainly carried on the system research for ball-milling and annealing, revealing the influence of lattice-defects for the photocatalytic performance. Meanwhile, the relationship of the different morphology and structure of bismuth molybdate by reflux method atdifferent pH value and the photocatalytic performance were revealed. The effect and law of the photoactivity were systematically studied on ZnO with lattice defects and the different bismuth molybdate.The repairment with annealing method on lattice-defects ZnO was studied. The defects of Zn O were formed via ball-milling treatment, and part of the defects could be repaired via annealing treatment. The density of states(DOS) of the photocatalysts valence band(VB), was regulated and controlled by the structure, number and the kind of lattice defects, which could affect the band gap and the separation efficiency of photoinduced electron and hole pairs, thus affecting the photocatalytic activity. A variety of technologies were utilized to reveal the physical structure of surface defects and bulk defects, and to display the external relations of defect states with the photodegradation process and the photocurrent, and to imply the inherent law of defect states with the separation and transfer of the photoinduced electrons. The photocatalytic activities achieved to the maximum when the temperature attains to 350 oC and the annealing time was 16 h. We believed that the bulk defects and a lot of nonradiative defects were formed after the milling treatment. The annealing treatment was a good method to repair parts of the lattice defects produced by the ball-milling.A series of bismuth molybdate photocatalyst with different pH value were prepared by the reflux method(100 oC, 12 h) under the room temperature. The results showed that the Bi2MoO6 sample obtained at the pH value of 6 exhibited the best photocatalytic activity by the photodegradation of MB under irradiation of visible light(λ > 420 nm). When the pH value was 6.5, the minor phase Bi2O3 was obtained with the production of heterojunction, which had a bad effect on the photoactivity. Under the alkaline conditions, Bi3.64Mo0.36O6.55 phase was produced and unfavorable for the photocatalytic activity.