Surfactant effects on pH-controlled synthesis of nickel hydroxides

The aim of the present work is to determine at 60 degrees C, the influence of the specific nature of nickel salt and pH on nickel hydroxide features such as crystallographic structure and morphology. Within the range 8 < pH < 11.5, a home-made nickel functionalized surfactant, nickel di-dodecylsul fate Ni(C12H25SO4)(2) is compared to usual salts (nickel nitrate Ni(NO3)(2) and nickel sulfate NiSO4). In both cases, a sharp transition appears for pH about 10. In the classic salt case, the transition mainly affects morphology, that could be evidenced by the crosschecking of complementary techniques as SEM and nitrogen gas adsorption. For pH < 10, beta-Ni(OH)(2) platelets are yielded, whereas more basic conditions lead to randomly aggregated nano-grains of badly crystallized 0 hydroxide. Inversely, by employing the functionalized surfactant, 2D morphology is maintained in the whole pH-range, but the crystal structure is pH-controlled alpha phase with interlamellar dodecylsulfate for pH < 9.5, and beta phase for pH > 10.5). (c) 2006 Elsevier B.V. All rights reserved.