形貌可控ZnO微纳米结构的水热合成及光催化性能

以乙醇胺为辅助溶剂,采用水热合成法,制备了花状、梭状和剑状的ZnO微纳米结构。采用扫描电镜(SEM)、X射线衍射(XRD)、光致发光光谱(PL)和拉曼光谱等测试手段对样品的形貌、结构、晶相等进行了表征。结果表明所有样品均为六方纤锌矿结构ZnO;其形貌和结晶度可通过改变物质的量的配比nZn2+/nOH-来调控。探讨了反应物配比对产物形貌结构的影响,乙醇胺对不同形貌ZnO的制备起到至关重要作用。以亚甲基蓝为目标降解物,采用紫外-可见吸收光谱(UV-Vis)并结合低温氮吸附-脱附比表面测试(BET),研究了花状、梭状和剑状ZnO的光催化活性。结果表明,与商用ZnO相比,制备的ZnO具有更好的光催化活性;样品催化活性与其比表面积不成正比,具有最小比表面积的花状ZnO拥有最好的光催化活性,这可能是由于其低的结晶度和特殊的花状形貌所致。

ZnO Micro-Nanostructures: Controllable Hydrothermal Synthesis and Photocatalytic Activity

Flower-like, spindle-like and sword-like ZnO micro-nanostructures were synthesized via an ethanolamine-assisted hydrothermal method. The morphology and structure of as-prepared ZnO products were characterized by XRD, SEM, low temperature nitrogen adsorption-desorption(BET surface area), photoluminescence(PL) and Raman spectroscopy. The effect of n_Zn²⁺/n_OH^- ratio on the morphology of ZnO products was discussed, and the photocatalytic performance was also tested in terms of the organic dye methylene blue degradation. The results demonstrate that all the prepared products possess a wurtzite structure. Their morphology and crystallinity can be controlled by adjusting the molar ratio between Zn²⁺ and OH^-. The ethanolamine is an indispensable solvent in the formation of ZnO products. Compared with commercial ZnO, the prepared ZnO products have higher photocatalytic activity. However, there is no correlation between the BET surface area and the photocatalytic activity. The flowerlike ZnO with a minimum surface area exhibits the highest photocatalytic activity, which can be attributed to its lower crystallinity and special flower-like structure.