Property And Photocatalytic Performance Based On ZnO Thin Film

With the rapid development of industry and population,global environmental pollution and energy supply need to be solved urgently.As people gradually realize the problem of environmental protection and the shortage of clean water resources,the degradation of organic pollutants in water has become a hot topic.Compared with traditional methods,such as adsorption,coagulation and membrane separation,semiconductor photocatalytic technology has a broad application prospect because of its higher efficiency.It has important application value in environmental protection and energy.The semiconductor materials represented by ZnO have attracted more and more attention.However,pristine ZnO has the wide band gap and it is easily photocorroed during the photocatalytic process,which prophibits the application of pristine ZnO.Combining with other semiconductors is one of the common used method to overcome the obstacles of ZnO photocatalysis.Here,the preparation and photocatalytic properties of ZnO/PANI and ZnO/g-C3N4 composites were studied.Nano flower like ZnO was prepared by acid corrosion method,and then,chemical adsorption method was used to prepare ZnO-PANI composites.Scanning electron microscope(SEM),X-ray diffraction(XRD),photoluminescence spectrum(PL),ultraviolet visible absorption spectroscopy(UV-Vis)and Mott-Schottky curve(M-S)were used to characterize materials.The effect of corrosion and adsorption time on the photocatalytic performance were studied.The results show that the corrosion time of Zn and the time of adsorption of PANI affect the morphology and properties of ZnO-PANI composites.The ZP-4 composite obtained under 8 min corrosion time and 150 min adsorption time presents the highest photocatalytic degradation efficiency to the degradation of methyl orange under visible light irridation,and the degradation rate is 97.2%in 180 min.Moreover,ZP-4 materials showed excellent photocatalytic stability,and the degradation rate decreased little during the 3 cycles degradation.For the photocatalytic activities of water splitting under simulated solar light irradiation,the ZP-2 sample obtained under the adsorption of 60min has the highest efficiency of hydrogen production,which is about 2 times that of a single ZnO.The photocatalytic properties of ZnO/PANI increased obviously,mainly due to the significant improvement of the separation efficiency of photo generated carriers.Based on the active matter capture experiment,hydroxyl radicals(·OH)and holes(h+)were proved to be the main active substances for the degradation of MO by ZnO/PANI composites.g-C3N4 and ZnO were compounded by acid soaking.The samples were characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),photoluminescence(PL),ultraviolet visible absorption spectroscopy(UV-Vis),Mott-Schottky curve(M-S),and photocurrent analysis.The effects of g-C3N4 amount and corrosion time on the photocatalytic property were studied.The results show that the corrosion time of zinc and the amount of adsorbed g-C3N4 both affect the morphology and properties of ZnO.The ZCN-2 sample obtained by soaking 4 min with 0.04 g g-C3N4 addition amount in H2SO4presents the highest photocatalytic degradation rate in the photodegradation of methyl orange under visible light irridation,and the degradation rate is 92%in 150 min.h+and·O2-are the main reactant of MO photodegradation in the ZnO/g-C3N4 system.At the same time,the ZCN-2 material exhibits excellent cyclic stability.The degradation rate remains unchanged after 2 cycles.In addition,the prepared ZnO/g-C3N4 thin film can be used for the water splitting in water-methanol system under simulated solar light irradiation.ZnO/g-C3N4 samples showed improved activities for water splitting than pristine ZnO.The best photocatalytic performance was obtained by ZCN-2,reaching 1.86 umol/(cm2·h),which is about 2 times as that of pristine ZnO.