SYNTHESES AND PROPERTIES OF COBALT AND NICKEL HYDROXIDE NANOSHEETS

Abstract

Nanosheets of cobalt and nickel hydroxides nanosheets were prepared by delamination of layered compounds, Co II( OH )1.73( DBS )0.27·0.87 H 2 O ( Co - DBS , DBS = dodecylbenzene sulfonate) and Ni II( OH )1.63( DBS )0.37·1.24 H 2 O ( Ni - DBS ), respectively. Powder X-ray diffraction analyses of the layered compounds revealed lattice parameters of a0 = 3.07 Å and c0 = 30 Å ( Co - DBS ) and a0 = 3.09 Å and c0 = 30 Å ( Ni - DBS ) in the hexagonal system. Dispersions of Co - DBS and Ni - DBS in 1-butanol produced colloidal solutions of nanosheets, [ Co - DBS ] delam and [ Ni - DBS ] delam , respectively. Poly(vinylpyrrolidone) ( PVP ) was dissolved in [ Co - DBS ] delam and [ Ni - DBS ] delam and the mixtures were dried to yield Co - PVP and Ni - PVP , respectively. These nanosheets measured 150-500 nm for [ Co - DBS ] delam and 135-400 nm for [ Ni - DBS ] delam by means of dynamic light scattering. Atomic force microscopy images showed lateral dimensions of 100-500 nm for [ Co - DBS ] delam and 50-100 nm for [ Ni - DBS ] delam . In the former image, the cobalt hydroxide nanosheets had a fairly flat terrace structure with thickness of 3.1-3.6 nm and with aspect ratios of 30-150, whereas in the latter image dome-like nanosheets of nickel hydroxide with height of 2.2-2.3 nm were confirmed. These nanosheets were regarded as monolayer. Magnetization experiments at 1.8 K showed hysteresis loops for Co - DBS , Co - PVP , Ni - DBS , and Ni - PVP .