| Photocatalysis has advantages of high efficiency,protecting environmental and low cost,it has broad application prospects in environmental purification,especially in water treatment.ZnO has the characteristics of suitable band gap,high chemical stability,high electron mobility,good biocompatibility,safety and environmental protection,which have attracted many scholars to research.However,the wide band gap and fast recombination of photogenerated carriers limit the practical application of ZnO.Therefore,in this paper,the modification strategy of cobalt doping and heterojunction construction is adopted to modify ZnO,and it was grown in situ on ITO conductive glass.Through the adjustment of band gap width,the improvement of light absorption ability and the separation and transfer ability of photogenerated carriers,the problem of difficult recovery of traditional photocatalysts is can be solved while improving the photocatalytic degradation performance of materials.The main work is as follows:(1)Cobalt-doped ZnO(Co-ZnO)thin films were prepared by hydrothermal method,and the effect of cobalt doping concentration on the photocatalytic degradation performance of Co-ZnO was investigated.The results show that CoZnO exhibits better photocatalytic degradation performance than ZnO.Co-ZnO with a cobalt doping concentration of 5% has the highest photocatalytic degradation performance,and the photocatalytic degradation efficiency of Rhodamine B(Rh B)within 120 min is 55.34%,which is 1.8 times that of ZnO.The improvement of photocatalytic degradation performance is the result of the combined effect of the reduction of the forbidden band width,the increase of the number of carriers and the rapid separation and transfer of photogenerated carriers.In addition,Co-ZnO also showed good stability and facile recyclability.The photocatalytic degradation mechanism of Co-ZnO is proposed based on the capture results of active species and the determination of the energy band positions of the materials.(2)Cd S was grown on ZnO thin films prepared by Electrodeposition by hydrothermal method,and Cd S/ZnO heterojunction composites(CZ)with good light absorption ability were prepared.The effect of cadmium zinc molar ratio on the photocatalytic degradation of CZ was investigated.The results show that Cd S plays a crucial role in the enhancement of CZ light absorption capacity.The formation of Z-scheme heterojunction effectively reduces the recombination degree of photogenerated carriers and enhances the photocatalytic degradation performance of CZ.CZ with a cadmium-zinc molar ratio of 1:1 has the best photocatalytic degradation performance.The photocatalytic degradation efficiency of Rh B within 120 min is 69.52%,which is 2.5 times of ZnO and 1.5times Cd S,and shows good stability.Furthermore,the photocatalytic degradation mechanism of CZ is proposed based on the capture results of active species and the determination of the energy band positions of the materials.(3)The Bi OI/ZnO heterojunction composite(BZ)was prepared by growing Bi OI on the ZnO thin film by the successive ionic layer adsorption reaction method,and the effect of the number of Bi OI cycles on the photocatalytic degradation performance of BZ was investigated.The research results show that the recombination of Bi OI significantly improves the light absorption capacity of BZ,which broadens the light absorption range of BZ to the visible light region.The heterojunction structure of BZ promotes the separation of photogenerated carriers and retains the holes and electrons with strong oxidation and reduction ability in BZ,so that BZ can produce more active substances in the process of photocatalytic degradation and improve the photocatalytic degradation performance of BZ.When the number of cycles is 90,the prepared BZ has the highest photocatalytic degradation performance,and the photocatalytic degradation efficiency of Rh B within 120 min is 78.31%,which is 2.7 times of ZnO and 1.8 times of Bi OI.BZ exhibits excellent stability and rapid recyclability. |
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