水热改性法制备分散性纳米氧化镍

Formation of Dispersive NiO Nano-particles via Hydrothermal Modification

摘要:

以NiCl2 和NH4HCO3为原料, 探讨了采用常温合成-水热改性-中温焙烧工艺制备分散性纳米NiO的可行性。常温条件下制备的产物主要由NiCO3 Ni(OH)2和Ni(OH)2微晶相组成且团聚现象突出;水热改性可进一步促进沉淀的形成,降低产物中Ni(OH)2及水分含量,使后继焙烧产物(纳米NiO)的分散性得到显著改善。热力学计算表明: 在Ni2+-NH3-CO32--H2O体系中, 升高温度有利于镍氨络离子的解离, 促进NiCO3 和Ni(OH)2沉淀的形成。温度越高,形成NiCO3的热力学可能性越大。

Abstract:

By mixing NiCl2 and NH4HCO3 solutions at room temperature, NiO nano-particles were synthesized by hydrothermal modification and sintering. The agglomerated amorphous precipitates formed at room temperature were mainly composed of NiCO3. Ni(OH)2 and Ni(OH)2 crystallites and were converted to deposits with higher crystallinity and less content of Ni (OH)2 and H2O after hydrothermal treatment. NiO nano-particles prepared from the hydrothermal deposits were of higher dispersion than those from the amorphous precipitates. The primary thermodynamic calculation in Ni2+-NH3-CO32--H2O system indicated that the rise of temperature is favorable for the release of Ni2+ from the Ni2+-NH3 complex ions, accelerating the formation of NiCO3 and Ni (OH)2. The thermodynamic possibility for the formation of NiCO3 phase increased with the increase of temperature.