Preparation And Photocatalytic Property Of ZnO Nano-composites

In recent decades,given the social and economic progress made people's lives have become increasingly comfortable.However,the environmental pollution and energy shortage phenomenon has become a global problems,and should give priority to the implementation of China's strategy of sustainable development.Therefore,how to solve the problem of pollution prevention and control of ecological environment has become the top priority problem of the government,enterprises and the scientific community in twenty-first Century.Photo-catalytic degradation technology is a kind of economic,safe,efficient,no second pollution?simple and feasible solution.Green technology for converting natural rich light energy into chemical energy and electric energy.It is not only of a practical significance but also of far-reaching historical significance in the protection of the natural environment and the maintenance of ecological balance by the direct use of solar photo-catalytic degradation of organic pollutants in waste water and waste.In many semiconductor photo-catalytic materials,ZnO has become the most promising photo-catalyst because of its high electrochemical stability,cheap,non-toxic,recyclable and so on.But in practice,due to the band gap of ZnO?3.3eV?is wide,the solar energy utilization rate is low,the photogenerated electron recombination of fast,lead to quantum efficiency low,limiting the ZnO in the field of photocatalytic activity and application.Therefore,in this paper,through the effective way to modify the ZnO ? ZnO and carbon?C?,graphite phase carbon nitride?g-C₃N₄?,carbon nanotubes?CNT?to form a composite material to improve the photocatalytic activity of ZnO.1.zinc acetate as a precursor,using thermal decomposition method microwave method,,microwave hydrothermal method and sol-gel method to prepare ZnO photocatalytic materials with different photocatalytic properties,and product structure and optical performance were measured.The photocatalytic activity of the materials was discussed.The photocatalytic activity of the prepared samples was evaluated by the degradation of Rhodamine B.The effects of reaction temperature and reaction time on the crystal structure,optical and photocatalytic properties of the photocatalyst were studied.The results show that the four methods can be used to synthesize wurtzite ZnO,and the reaction temperature is350?,the reaction time is10 min,the photocatalytic performance of ZnO is the best.2.A series of ZnO/C nanocomposites were successfully prepared by one-stephigh temperature solution.Secondly,the morphology,crystal structure and optical properties of the catalysts were characterized by XRD,TEM and UV-VIS.The photocatalytic degradation of methylene blue by the prepared photocatalyst showed that the photocatalytic activity of ZnO/C?1.5%?composite was the best.The first order kinetic equation was used to study the kinetics of the best composite ratio.The results show that with the increase of the reaction temperature,the reaction rate constant increases and the half-life decreases.According to the fitting curve,the average activation energy is 18.06kJ/mol.3.ZnO/g-C₃N₄ nanocomposite photocatalysts with visible light was synthesized by microwave method.The morphology,crystal structure and optical properties of the catalysts were characterized.In xenon light irradiation,the degradation of Rhodamine B prepared to evaluate the photocatalytic activity of samples.The experimental results show that the photocatalytic activity of the prepared ZnO/g-C₃N₄ composites is the best when the g-C₃N₄ content is 1.0%.The first order kinetic equation was used to study the kinetics of the best composite ratio.The results show that the reaction rate constant increases with the increase of the reaction temperature,and the half-life is shortened.According to the fitting curve,the average activation energy is 33.71kJ/mol.Fourier transform infrared spectroscopy was used to characterize the Rhodamine B and degradation products.Infrared spectrum experiment display that,the characteristic peaks of Rhodamine B gradually disappeared and the benzene ring structure damage,confirmed ZnO/g-C₃N₄ photocatalyst in a short period of time will be the effective degradation of Rhodamine B.4.ZnO/CNT nanocomposite photocatalytic materials were prepared by sol-gel method.And by using X ray diffraction?XRD?,transmission electron microscopy?TEM?and ultraviolet visible spectrometer?UV-VIS?by means of the prepared photocatalyst morphology,crystal structure and optical properties of the corresponding characterization.On the xenon lamp irradiation experiments were performed to evaluate the photocatalytic activity of the material.The experimental results show that the introduction of CNT has better photocatalytic performance of ZnO/CNT composites,and the ZnO/CNT composite exhibits the best photocatalytic activity when the CNT content is 0.3%.The first order kinetic equation was used to study the kinetics of the best composite ratio.The results show that the reaction rate constant increases with the increase of the reaction temperature,and the half-life is shortened.According to the fitting curve,the average activation energy is30.66kJ/mol.