Department of Chemistry, Central College, Bangalore University, Bangalore 560 001, India.
Langmuir. 2010 Oct 5;26(19):15586-91. doi: 10.1021/la103108f.
Homogenous precipitation by formamide hydrolysis results in the formation of a formate-intercalated layered double hydroxide (LDH) of Ni(II) and Al(III). The formate-LDH is sensitive to the atmospheric humidity and reversibly exchanges its intercalated water with atmospheric moisture. The hydration/dehydration cycle is complete within a narrow range of 0-30% relative humidity with significant hysteresis and involves a randomly interstratified intermediate phase. When immersed in water, the formate ion grows its hydration sphere (osmotic swelling), eventually leading to the exfoliation of the metal hydroxide layers into lamellar particles having in-plane dimensions of 100-200 nm and a thickness of 9-12 nm. These nanoplatelets restack to thicker tactoids again upon evaporation of the dispersion. The intercalated formate ion can be exchanged with nitrate ions in solution but not with iodide ions. These observations have implications for many applications of LDHs in the area of carbon dioxide sorption and catalysis.
通过甲酰胺水解进行均相沉淀，会生成镍（II）和铝（III）的甲酸盐插层层状双氢氧化物（LDH）。甲酸盐-LDH 对大气湿度敏感，可与大气中的水分进行可逆的层间水交换。水合/脱水循环在相对湿度 0-30%的狭窄范围内完成，具有显著的滞后现象，涉及随机层间中间相。当浸入水中时，甲酸盐离子会扩大其水合球体（渗透膨胀），最终导致金属氢氧化物层剥离成具有 100-200nm 面内尺寸和 9-12nm 厚度的片状颗粒。这些纳米薄片在分散体蒸发时再次重新堆积成较厚的微纤。插层的甲酸盐离子可以与溶液中的硝酸盐离子交换，但不能与碘化物离子交换。这些观察结果对 LDH 在二氧化碳吸附和催化领域的许多应用具有重要意义。
