Synthesis, anion exchange, and delamination of Co-Al layered double hydroxide: Assembly of the exfoliated nanosheet/polyanion composite films and magneto-optical studies
Synthesis, anion exchange, and delamination of Co-Al layered double hydroxide: Assembly of the exfoliated nanosheet/polyanion composite films and magneto-optical studies
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DOI：
10.1021/ja0584471
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发表时间：
2006-04-12
影响因子：
15
通讯作者：
Sasaki, T
中科院分区：
文献类型：
--
作者：
Liu, ZP;Ma, RZ;Sasaki, T
本文系统地研究了Co-Al层状双氢氧化物（LDH）的合成、阴离子交换和脱层过程，旨在实现LDH纳米片/聚阴离子复合膜的制备和性能研究。在优化的反应条件下，用尿素法合成了横向尺寸为4 μ m的Co-Al-Co-3LDH六方片晶。用NaCl-HCl混合溶液处理Co-3（2-）-LDH可使其转化为Cl--LDH，并保持其高结晶度和六方片状形貌。LDH;用各种阴离子（如NO3-、ClO 4-、乙酸根、乳酸根、十二烷基硫酸根和油酸根）插层的Cl-LDH通过使用相应盐的阴离子交换过程进一步制备。不同阴离子形式的交换产物在甲酰胺中表现出不同的脱层行为。其中，NO3--LDH在剥离程度和剥离的纳米片的质量方面观察到最好的结果。分层得到含有横向尺寸高达2 μ π ι的明确限定的纳米片的粉红色透明悬浮液。将所得纳米片与阴离子聚合物聚（苯乙烯4-磺酸钠）（PSS）逐层组装到石英玻璃基底上以产生复合膜。磁性圆二色性（MCD）测量表明，组装的多层膜表现出有趣的磁光响应。
This paper describes a systematic study on the synthesis, anion exchange, and delamination of Co-Al layered double hydroxide (LDH), with the aim of achieving fabrication and clarifying the properties of LDH nanosheet/polyanion composite films. Co-Al-Co-3 LDH hexagonal platelets of 4 mu m in lateral size were synthesized by the urea method under optimized reaction conditions. The as-prepared Co-3(2-)-LDH was converted to Cl--LDH by treating with a NaCl-HCl mixed solution, retaining its high crystallinity and hexagonal platelike morphology. LDHs; intercalated with a variety of anions (such as NO3-, ClO4-, acetate, lactate, dodecyl sulfate, and oleate) were further prepared from Cl--LDH via an anion-exchange process employing corresponding salts. Exchanged products in various anion forms were found to show different delamination behaviors in formamide. Among them, best results were observed for NO3--LDH in terms of the exfoliating degree and the quality of the exfoliated nanosheets. The delamination gave a pink transparent suspension containing well-defined nanosheets with lateral sizes of up to 2 pm. The resulting nanosheets were assembled layer-by-layer with an anionic polymer, poly(sodium styrene 4-sulfonate) (PSS), onto quartz glass substrates to produce composite films. Magnetic circular dichroism (MCD) measurements revealed that the assembled multilayer films exhibited an interesting magneto-optical response.