One-step In-situ Synthesis Of Bi-based Hybrid Photocatalysts And Their Visible Light Photocatalytic Activities

With the continuous and fast development of our country’s industrialization and theincreasing people’s living standards, the problem of environment pollution from garbageand industrial waste becomes more and more serious. Semiconductor-based photocatalysishas a wide application prospect in degradation of pulluants for protecting environmentalenvironmental due to its advantages of low-cost, environmentally friendly, sustainability,etc. At present, most of the photocatalysts are of ultraviolet activity, and complicatedpreparation methods or costly synthetic procedures are needed to obtain them. Hencedeveloping visible-light-driven photocatalysts with facile synthesis process, low cost andhigh activity has attracted a great deal of attention. Among novel photocatalysts withvisible-light activities.Bi-based potocatalysts have drawn considerable interest due to theirenvironmentally friendly and high efficiency.In this thesis, the novel hybrid photocatalysts containing bismuth have beendeveloped. The as-prepared samples were characterized by X-ray diffraction (XRD),Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), UV-Visdiffuse reflectance (DRS), X-ray spectroscopy (XPS). The results show that the Bi-basedheterojunction nanomaterials exhibit good photocatalytic abilities under visible lightirradiation, which can be attributed to the introduction of photocatalyst with narrowenergy band gap, the cross conduction and valance band levels of the as-preparedheterojunctions, and hence the efficient reduces of the photo-generated electron (e-)–hole(h+) recombination efficiency.A novel heterojunction structure between BiOCl and C3N4was fabricated via anionic-liquid-assisted sol-vent thermal in-situ route.The hybrids have high contact areabetween the tow components, which facilitates the transfer of the photo-induced electronsof C3N4to BiOCl under visible light irradiation. When the molar ratio of BiOCl to C3N41:1, the obtained sample exhibits the highest photocatalytic activity. The MO removal canreach95%in80min under visible light irradiation, and the pseudo-first-order rate constantis0.0317min-1.Based on that various Bi-containing photocatalysts can be prepared by varying thedifferent proportions of Bi and halogen elements (X=Cl, Br), BiOCl-Bi24O31Cl10andBiOBr-Bi24O31Br10heterojunction materials have been developed via in-situ solution combustion method by changing the ratio of various raw materials The heterojunctionsexhibit excellent degradation abilities for pollutants under visible light. Theheterojunctions containing60%BiOCl or75%BiOBr show the highest hotocatalyticactivity, respectively. The results show that there are negative charges on the surface ofthe samples, which is benefit to the adsorption of samples for cationic dyes. The mainactive species generated in the photocatalytic process responsible for the degradation ofpollutants were investigated using the FL and radical scavengers. According to aboveexperimental results, potential photocatalytic mechanisms of the two hybrids are alsoproposed.