The Effect Of Structure Regulation On Semiconductor Photocatalytic Activity

The photocatalysts with phase-junction, defect-structure, heterojunction and compositestructure were synthesized by many methods such ashigh-energy ball milling and calcination. The adjustment of BiPO₄ photocatalytic performance and its reaction mechanism were studied with phase-junction and defect structure, the photocatlaytic activity of BiPO₄/Bi₂WO₆ was studied on the condition of full spectrum. The intrinsic role of graphene as conducting electronic cocatalyst on GR/TiO₂ composite photocatalyst were evaluated via the research of adsorption and photocatalytic performance, the enhancement of apparent rate constanton the graphene-based composite photocatalyst were rectified because the adsorption effect of graphene for the pollution is eliminated. Moreover, the photocatalytic performance of MoS₂/TiO₂ composites via ball-milling was further testified the influencing essence of conducting electronic cocatalyst to TiO₂.BiPO₄ with phase-junction were synthesized viacalcination on the condition of normal pressure and air.BiPO₄ with nMBIPand mMBIP phase-junction were prepared by adjusting temperature and time of calcination, enhanced the photocatalytic performance of degrading many kinds of organic pollutants. The formation of BiPO₄ phase-junction face effectively separate and transmit photo-generated charges, and further enhanced the ultraviolet photocatalytic activity.The defect-structures of BiPO₄ were generated by controllable ball-milling, and then they were repaired via calcination and reflux treatment. The influence of defects on the photocatalytic and photoelectric performance of BiPO₄ have been revealed. The enhancement of ball-milling rate and extension of ball-milling time produced more defect-structure, resulting in decrease of its photocatalytic performance. Many defect-structures of BiPO₄ were repaired by calcination and reflux, improved its photocatalytic performance. Reflux had better repaired abilityof BiPO₄ defect-structure than calcination.BiPO₄/Bi₂WO₆ heterojunction photocatalysts were prepared via ultrasonic and calcination methods, possessed excellent universal for many organic pollutants on the condition of full spectrum. In BiPO₄/Bi₂WO₆ composite photocatalysts, BiPO₄ nanorod as center and Bi₂WO₆ as outer layer like core-shell structure were formed. BiPO₄ could quickly separate the photo-generated holes of Bi₂WO₆, and Bi₂WO₆ could quickly separate and transmit the photo-generated electrons of Bi₂WO₆. The interaction between two semiconductors enhanced the separation of photo-generated charges and improved the photocatalytic performance of full spectrum.GR/TiO₂ and MoS₂/TiO₂ composite photocatalysts with noble metal-free as cocatalyst were prepared by solvothermal and ball-milling methods. Composite graphene can’t enhance the photocatalytic oxidation performance of TiO₂, the increased apparent rate constant k of GR/Ti O₂ is due to the lower reaction initial concentration caused by strong adsorption of graphene for pollutants. But graphene as a conducting electronic cocatalystcould effectively promote the migration of photo-generated electrons, resulting in an improved H2 evolution activity. The photocatalytic performance of MoS₂/TiO₂ composites further testified the intrinsic role ofconducting electronic cocatalyston the semiconductor photocatalysts.