不同形貌微/纳米ZnO的制备及光催化降解活性

Preparation and Photocatalytic Degradation Activity of Different Morphology Micro/Nano ZnO

以Zn(NO_3)_2·6H_2O、Zn(Ac)_2·2H_2O为锌源,NaOH、无水Na_2CO_3为碱源,采用不同的实验方法与工艺制备了绒球状、棒状、针状、晶须状等7种不同微观形貌与比表面积的微/纳米ZnO粉体材料。利用扫描电镜(SEM)、X射线衍射(XRD)对产物进行结构和性能表征。配制紫林兰G工业染料稀溶液,选取7种不同形貌的ZnO微/纳米材料作为光降解催化剂,分别在自然光和400W紫外光下对其进行光催化降解性能的对比研究。结果表明,单纯的紫外光也能使染料溶液脱色,但很难达到彻底降解的目的,而微/纳米ZnO在紫外光或可见光下都能使染料溶液彻底降解。不同形貌微/纳米ZnO的光催化降解活性不同,材料的光催化降解活性与粉体材料比表面积高度相关。对于染料稀溶液,因直接沉淀法制备的产物经煅烧而获得的粉体比表面积达36.3m2/g,显示更高光催化活性。不管何种形貌催化剂,在紫外光下的降解速率要比自然光下的快。

Seven kinds of different micro-morphologies and specific surface areas of micro/nano ZnO powder materials, pompon-, rod-, needle-, whisker-like and so on, have been synthesized by using different experimental methods and processes, with Zn（NO 3） 2·6H 2O, Zn（Ac） 2·2H 2O as zinc sources, and NaOH, anhydrous Na 2CO 3 as alkali sources.. The structures and properties of the products were characterized by scanning electron microscopy （SEM） and X-ray diffraction （XRD）. For the prepared dilute solutions of purple forest blue G industrial dye, the photocatalytic degradation performances of ZnO micro/nano materials were studied with different seven morphologies as photodegradation catalysts. The photocatalytic degradation experiments were comparatively carried out in both natural light and 400 W UV light respectively. The structure-activity relationship of photocatalytic degradation of different morphologies micro/nano ZnO was compared. The results show that pure UV light can also decolorize the dye solution, but it is difficult to achieve the purpose of complete degradation, while micro/nano-ZnO in the ultraviolet light or visible light can make the dye solution completely degraded. The photocatalytic degradation activity of different morphologies of micro/nano ZnO is different, and the photocatalytic activity of the material is highly correlated with the specific surface area of the powder material. For the experimental dilute solution, the prepared product was calcined by using the direct precipitation method to obtain a powder with specific surface area of 36.3 m 2/g, which showed higher photocatalytic activity. No matter what kind of morphology catalyst, in the UV light, the degradation rate become faster than in natural light.