Preparation And Properties Of Ni²⁺-Cu₂O/ZnO Composite Filmes

With the rapid development of industrial and agricultural production and the improvement of people’s living standards,the problem of water resources caused by environmental pollution has attracted wide attention,and it is urgent to control the problem of water resources.Cu₂O is a narrow bandgap semiconductor material with a bandgap of about 1.9～2.3eV.It has good absorption of visible light.Its advantages include low cost,non-toxicity and no secondary pollution.In addition,Cu₂O has potential applications in photocatalytic degradation of organic pollutants for wastewater treatment.However,the combination of photoelectrons and holes in Cu₂O semiconductor is high,which limits its application.The purpose of this study is to reduce the recombination probability of Cu₂O photogenerated electrons and holes and improve the utilization of sunlight by recombination and doping of Cu₂O.Cu₂O thin films,Ni²⁺-Cu₂O thin films,Cu₂O/ZnO composite thin films and Ni²⁺-Cu₂O/ZnO composite thin films were prepared on ITO glass substrates by electrochemical deposition in a three-electrode electrochemical system.XRD,UV-Vis and SEM were used to characterize and analyze its microstructure,surface morphology and photoelectric properties.The photocatalytic activity was also studied.Specific research contents and conclusions are as follows:（1）Preparation of Cu₂O thin films.Cu₂O thin films were prepared by electrochemical deposition,and the effects of electrolyte on the properties of Cu₂O thin films under different stirring conditions were discussed.The results show that the Cu₂O thin films（111）facets grown under ultrasound conditions are preferred,with a band gap of 2.06 eV,a wide optical absorption range and a good morphology and structure.The electrochemical performance test showed that it had excellent light response,the degradation rate of methylene blue and amoxicillin reached 95.3%and 30.6%,respectively.（2）Preparation and properties of Ni²⁺-Cu₂O thin films.Ni²⁺-Cu₂O thin films were prepared by doping.The effect of Ni²⁺doping amount on the properties of Ni²⁺-Cu₂O thin films was discussed.The results show that the Ni²⁺-Cu₂O thin films with 0.25 mmol doping have better properties,and the（111）surface of the Ni²⁺-Cu₂O thin films is preferred to grow.The band gap is 2.06 eV.The Rct values in both light and dark states are small and have excellent light response properties.（3）Preparation and properties of Cu₂O/ZnO composite films.ZnO thin films were prepared by electrochemical deposition method,and Cu₂O/ZnO composite thin films were prepared on the basis of ZnO thin films.The characterization and analysis of the composite thin films were carried out.The results show that the peak shapes of ZnO films and Cu₂O/ZnO composite films are good,the band gaps are 3.37eV and 2.18eV,respectively.The photocurrent and open-circuit voltage of Cu₂O/ZnO films are higher than that of Cu₂O films.The Rct values of both light and dark states are decreased,and the morphology of the composite films is uniform and compact.Photocatalytic degradation experiments show that the degradation rate of methylene blue by Cu₂O/ZnO films is higher than that of Cu₂O films up to 95%.（4）Preparation and properties of Ni²⁺-Cu₂O/ZnO composite films.Ni²⁺-Cu₂O/ZnO composite films（111）have preferred orientation on crystal plane,band gap is about 2.11 eV,photocurrent and circuit voltage are larger than those of Cu₂O/ZnO and Cu₂O films,and the morphology is more compact and uniform.At the same time,the photocatalytic degradation conditions of methylene blue by Ni²⁺-Cu₂O/ZnO composite films were optimized by response surface design.The optimum degradation conditions for the selected model were obtained as follows:initial pH value of methylene blue solution was 5.6,initial concentration was 30 mg/L,and the amount of hydrogen peroxide was 0.75 mL.Under the optimum conditions,the photocatalytic degradation rate of methylene blue by Ni²⁺-Cu₂O/ZnO composite film was 99.96%and 98.92%respectively.The difference between the real value and the predicted value was very small,which indicated that the selected model was accurate.