| Recently, nano-scale ZnO was found to have significant opportunity in providing electronic, photonic,and spin-based functionality (spintronics) because of its direct wide band gap (3.37eV) and large excitonbinding energy of～60meV. For the semiconducting materials, This makes ZnO worthy in the potentialand established hi-tech applications such as ceramics, piezoelectric transducers, optical coatings, highspeed and display devices, gas sensors, varistors, photocatalysts, and photovoltaics. Also the high chemicalstability and low toxicity together make ZnO suitable for UV screening applications. The application ofsemiconductors such as ZnO in the area of photocatalysis has grown considerably, primarily because oftheir physical and chemical stability, high oxidative capacity, low cost and ease of availability.Disadavantageously, the rapid recombination of the excited electron-hole pairs and limited available sunenergy spectrum limit the applications in photocatalysis. It found that to design composite materials cangreatly improve the photomance.Based on the above analysis, this paper studies ZnO as the main line, photocatalysis performance asthe research content, through the synthesis of different composite materials to its photocatalysisperformance test separately, the concrete content as follows:1. One step to synthesis zinc oxide/silver/graphene composite material, use oxidation of graphene forsolvent solution, and give it to join with zinc sulfate, sodium hydroxide, nitricacid silver, ascorbic acid(reduction oxidation graphene and nitricacid silver), and the generation of zinc oxide particles and thesilver grains. At the same time, different amount of nitricacid silver and different amount of graphene areproceed degradation test separately, found that nitricacid silver, oxidation of graphene’s dosage has anoptimal value,which leads to the different degradation rate. In addition, in excitation of ZnO by light,electronic could migrate to the surface of silver grains or single silver particles, thus, cause photocarriereffective separation, so as to enhance the efficiency of zinc oxide catalyst.2. Two Step to synthetic zinc oxide/cadmium sulphide composite. Firstly, with hydrothemal method tosynthesis zinc oxide which is composed of thin sheets. By adding chlorinated cadmium, the source ofcadmium on the sphere of zinc oxide formed, and then adds thiourea use ultrasound chemical method in the last generation of cadmium sulphide particles. Secondly, to add different amounts of cadmium and thioureachloride, generating different amounts of cadmium sulphide particles, and depending on the amounts ofcadmium sulphide particles on ZnO to degradation test again. Because of ZnO and CdS has differentstructure characteristics, after ZnO and CdS integrated the composite can broaden its absorption area;Another reason is the two structure has so many differences,so it can easily lead to a changing environment,making the surface defects increase, so that both the photocatalysis activity area and the active site areincreased. These two factors to make ZnO photocatalysis performance improved.3. In this work, a facile surfactant-directed process is developed for controlling the morphology ofZnO with distinctive shapes ranging from mushrooms, bihemispheres, dumbbells, bilayer hexagonal disksand prisms. The hexagonal disks and prisms1-2μm in diameter and50nm to approximately4μm inthickness (or length) were enclosed by {1010} facets. The growth mechanism of these bilayer hexagonalstructures was studied by microscopy and spectroscopy. In addition, by replacing the conventionaloil-water system, the simple alcohol-water surfactant system employed here provides a moreenvironmentally benign and biosafe approach. |
PDF Full Text Request