Liquid-Liquid Biphasic Synthesis of Layered Zinc Hydroxides Intercalated with Long-Chain Carboxylate Ions and Their Conversion into ZnO Nanostructures
Liquid-Liquid Biphasic Synthesis of Layered Zinc Hydroxides Intercalated with Long-Chain Carboxylate Ions and Their Conversion into ZnO Nanostructures
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DOI：
10.1021/ic1025729
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发表时间：
2011-04-18
影响因子：
4.6
通讯作者：
Fujihara, Shinobu
中科院分区：
文献类型：
--
作者：
Inoue, Sara;Fujihara, Shinobu
采用不互溶液-液体系，一锅法高产率合成层状氢氧化锌化合物。长链羧酸根离子如庚酸根、癸酸根和十二酸根在一个过程中成功地插层在氢氧化锌层之间，该过程从二甲苯-水体系开始。通常，使溶解相应羧酸的二甲苯相与溶解六水合硝酸锌和尿素的水相接触。在将所得两相体系保持在80 ℃的过程中，尿素被热水解以在水相中提供OH（-），而羧酸根据分配定律从二甲苯相中连续转移。然后使水相过饱和，并通过非均质成核和随后的二维晶体生长将层状碱性羧酸锌的固相沉淀为玻璃基板上的膜。薄膜的晶体结构和形貌由所用的羧酸的种类调制。层状碱性羧酸锌薄膜可以通过在空气中在450 ℃下加热转化为纳米结构的中孔ZnO薄膜。系统地考察了两相体系中初始溶液组成与最终固体产物之间的关系，探讨了两相体系中的反应机理。
A method for synthesizing layered zinc hydroxide compounds in high yields is developed using an immiscible liquid-liquid system in one pot. Long-chain carboxylate ions such as heptanoate, decanoate, and dodecanoate were successfully intercalated between zinc hydroxide layers in one process starting from a xylene-water system. Typically, a xylene phase dissolving the respective carboxylic acids was allowed to stand in contact with an aqueous phase dissolving zinc nitrate hexahydrate and urea. During keeping the resultant biphasic system at 80 degrees C, urea was thermo-hydrolyzed to supply OH(-) in the aqueous phase while the carboxylic acids were continuously transferred from the xylene phase under the distribution law. The aqueous phase was then supersaturated, and a solid phase of layered basic zinc carboxylate was precipitated as films on glass substrates through heterogeneous nucleation and subsequent two-dimensional crystal growth. Crystal structures and morphology of the films were modulated by the kind of the carboxylic acids employed. The layered basic zinc carboxylate films could be converted to nanostructured, mesoporous ZnO films by heating at 450 degrees C in air. The relationship between the initial solution compositions and the final solid products was systematically examined to discuss reaction mechanisms in the biphasic systems.