Study On Co-deposition Of Zno-doped Semiconductor Heterojunction And Its Photocatalytic Performance

Due to its excellent properties,zinc oxide（Zn O）has been widely used in photocatalytic degradation of organic pollutants and photocatalytic cracking of water to produce hydrogen and oxygen.However,the wide band gap and low quantum efficiency limit the photocatalytic activity of Zn O.The transition metal doping modification of Zn O has become one of the research hotspots in recent years.In this paper,based on the glancing Angle co-deposition technology of magnetron sputtering method,Fe and V doped Zn O films with different doping ratios were prepared.By means of SEM,XRD,UV-Vis,EDS and photodegradation,the morphology,optical properties,electrical properties and photocatalytic properties of the two doping systems were studied,and the optimal doping ratio was found.The relative heterostructures were prepared on the basis of appropriate amount of V-doped Zn O thin films to find the optimal heterostructures,and the internal mechanism of the improvement of photocatalytic activity was discussed.1.A new type of Fe-doped Zn O thin film was prepared by magnetron sputtering glancing angle deposition technology,and the surface morphology of the material was controlled by adjusting the sputtering power.In the case of small Angle sputtering,the diffusing ability of Fe atoms is lower than that of Zn and O atoms.In the case of shadow effect,the sample is easy to form complex nanostructures.Through the characterization and analysis of the samples,it was found that the morphology and structure of the samples,the photocatalytic degradation of methylene blue and the photocatalytic cracking of water are related to the amount of Fe element introduced.Among them,the photocurrent response value of 75.46%Fe doped sample is 10 times that of pure Zn O film,showing the best photocatalytic activity.2.A batch of V-doped Zn O films with different doping ratios were prepared by co-sputtering deposition method at one time.The atomic ratio of V:Zn was effectively controlled by adjusting the different substrate positions and the distance between target groups.The introduction of metal elements has obvious effects on the morphology,energy band structure and photoelectric properties of materials.It was found that the impurity level introduced increases the band gap width of the film with a small amount of doping,and the formation of V_xO_y in the film reduces the band gap width gradually with the increasing of the proportion of V doping.The comparison shows that the sample A with the target base distance of 9 cm（V atom doping ratio of 15%）shows the best photocatalytic cracking water stability,indicating that the introduction of V improves the separation and migration efficiency of photogenerated carriers,reduces the resistivity,effectively controls the flat band potential of the film,and enhances the activity of the sample for photocatalytic cracking water to produce oxygen.3.Based on previous work experience,the magnetron sputtering technology was used to deposit W doped Fe₂O₃ film and Zn O on the basis of V-doped Zn O thin films to construct the corresponding heterojunction,so as to further enhance the response of the material in visible light and the activity of cracking water to produce oxygen.In the W-doped Fe₂O₃films with different doping ratios,the sample with the W-doped ratio of 26.9%has a higher absorption rate to visible light due to its mixed phase structure,which enhances the photocatalytic activity.Both Zn_xV_yO/Zn O and Zn_xV_yO/Fe_xW_yO composites are n-n type heterojunction.In the process of photocatalytic electrolysis of water,Zn_xV_yO/Zn O composite film shows the best activity for photocatalytic water cracking.The internal mechanism of performance improvement of composite material is analyzed by electrochemical workstation test and energy band structure diagram.