微/纳米ZnO粉体在Glu-BF_4离子液体水溶液中的诱导生长

Induced Growth of Micro/nano ZnO Powder via Glu-BF_4 Ionic Liquid Aqueous Solution

以一定浓度谷氨酸-氟硼酸(Glu-BF_4)离子液体水溶液为反应介质,摩尔比为1∶6的二水合醋酸锌和氢氧化钠为反应物,在室温下制备前驱体,再通过微波辅助加热制备了具有绒球形貌的微/纳米ZnO粉体.利用扫描电子显微镜(SEM)、X射线衍射仪、比表面积测试仪、能谱仪、拉曼光谱仪和透射电子显微镜(TEM)等对产物形貌、晶型、比表面积、组成和晶面分布进行了测定.结果显示,所得产物为六方晶系纤锌矿结构,平均粒径20.4 nm,绒球大小1.6~3.0μm,比表面积为28.3 m^2/g,产物纯度较高.当反应物浓度一定,离子液体浓度分别为0.02,0.04,0.08和0.12 mol/L时都得到了类似形貌的微/纳米ZnO粉体,且随着离子液体使用量的增加,绒球尺寸分布更加均一.当离子液体浓度一定,而反应物浓度逐渐下降时,产物形貌发生递变性变化.ZnO晶粒在Glu-BF_4离子液体诱导下首先生成不规则的纳米片,纳米片进一步聚集,在一定反应物浓度范围内生成绒球形貌粉体,反应物浓度较低时只生成绒球的核心部分,而浓度更高时则生成纳米针阵列.通过不同条件下纳米ZnO粉体形貌变化规律,探讨了强碱性条件下Glu-BF_4离子液体水溶液中微/纳米ZnO粉体的生长机制.

In this study,pompon-like micro / nano ZnO powders have been synthesized via microwave assisted heating of the precursors which were prepared with Zn（ OAc）2·2H2O and Na OH（ molar ratio 1 ∶ 6） as reactants and Glu-BF4 ionic liquid aqueous solution as reaction medium at room temperature. The products were characterized by scanning electron microscopy（ SEM）,X-ray diffraction（ XRD）,specific surface area analysis,energy spectroscopy（ EDS）,Raman spectroscopy and transmission electron microscopy（ TEM）,respectively. The results show that the prepared product has hexagonal wurtzite structure with high purity,the average particle diameter is 20. 4 nm,the size of pompon-like structure is about 1. 6—3. 0 μm and the BET surface area is 28. 3 m2/ g. When the concentration of the reactant was fixed,micro / nano ZnO with similar morphologies was synthesized using different dosages of ionic liquid,and with increase of the ionic liquid dosage,the size distribution of particles became more uniform. When the ionic liquid concentration was fixed,the morphology of product changed gradually with the decrease of the reactant concentration. Under the induction of Glu-BF4 ionic liquid,ZnO crystal grains firstly formed irregular nanosheets,then those nanosheets further aggregated to form the pompon-like powder in certain range of reactants concentration. Only the core part of the pompon-like powder was synthesized when the reactants concentration was relatively lower,while the nano-array morphologies were generated at higher reactant concentrations. In addition,the growth mechanism of micro / nano ZnO powder induced by Glu-BF4 ionic liquid aqueous solution under strong alkaline condition was discussed via morphology change tendency of nano ZnO powder under different conditions.