微波辐射对纳米ZnO材料物理性质与光催化活性的影响

在采用沉淀法制备ZnO的过程中, 用不同功率(100, 150, 200, 250和300 W)的微波辐射ZnO前驱体, 获得了一系列纳米ZnO材料, 并对合成材料的晶型结构、 形貌及表面物理化学性质进行了表征. 结果表明, 与普通沉淀法制备的ZnO相比, 使用微波辐射后ZnO半导体材料的晶型仍为六方纤锌矿结构, 但吸收光谱发生了蓝移或红移, 且比表面积均有不同程度的增加. 同时, 微波辐射功率不同, ZnO形貌差异明显, 并随着微波功率变化分别呈现纳米颗粒、 椭圆形纳米团簇、 纳米片和球状纳米簇等多样化形态. 以罗丹明B为模型分子, 分别在紫外及微波辅助光催化条件下考察了所合成纳米ZnO材料的光催化性能. 结果显示, 经不同功率微波辐射作用后, ZnO的光催化活性均得到了不同程度的提高, 并且明显高于市售P25和未经微波辐射作用的ZnO.

Effect of Microwave Irradiation on Physical Properties and Photocatalytic Activities of ZnO Nano-material

A series of ZnO nano-materials was prepared by sedimentation method under different microwave power(100, 150, 200, 250 and 300 W) irradiation. The crystal structures, morphologies and surface physicochemical properties of the as-prepared samples were characterized by X-ray diffraction(XRD), UV-Vis diffuse reflectance spectrum(UV-Vis/DRS), scanning electron microscopy(SEM) and N₂ adsorption/desorption determination. The results indicate that the crystalline phase of ZnO sample with different microwave power irradiation is hexagonal wurtzite, moreover, compared with the ZnO prepared by conventional sedimentation, there are blue shift or red shift in the absorption spectra, and the specific surface area is increased more or less. The morphology of each ZnO sample is much distinctive because of the different microwave power, which shows many kinds of shape including nano-grain, oval nano-clusters, nano-plane, spherical nano-clusters and so on. Photocatalytic properties of the ZnO nano-materials were tested by the UV irradiation and microwave-assisted photodegradation of Rhodamine B(RhB). The results show that the photocatalytic activities of ZnO prepared under different microwave power irradiation are enhanced in different degrees, which are much higher than that of P25 and ZnO sample without microwave irradiation.