The pH effects on the formation of Ni/Al nitrate form layered double hydroxides (LDHs) by chemical precipitation and hydrothermal method

The Ni/Al nitrate form layered double hydroxides (LDHs) were successfully synthesized at atmosphere condition by chemical precipitation and hydrothermal methods through pH control. Samples obtained at various pH conditions were characterized by XRD, FT-IR, TG-MS, ICP/AES and CHN element analyses. It was found that at low pH value, nitrate hydrotalcite was obtained, while at high pH value, carbonate hydrotalcite was produced. Ni/Al nitrate form LDHs particles with good crystallinity were obtained by hydrothermal treatment. SEM and TEM images show that the particle processes classical hexagonal shape. The transformation mechanism of the Ni/Al LDHs between nitrate and carbonate form under pH control was also discussed. This study offers a simple method to produce Ni/Al nitrate form LDHs with good crystallinity without controlled environment to exclude CO2 just by controlling the pH value. (C) 2010 Elsevier B.V. All rights reserved.