Surface properties of Ni+Co mixed oxides: a study by X-rays, XPS, BET and PZC

Samples of Ni and Co mixed oxide in the form of powders were synthesised by thermal decomposition of the nitrates at 400 degrees C. The samples were c haracterized by XRD for the crystal structure, XPS for the surface composit ion, the BET method for the surface area and by potentiometric titration to measure the point of zero charge (pzc). Lattice parameters and average cry stallite size have been obtained from the X-ray analysis, the surface compo sition shows strong enrichment with Ni, while the pzc increases from 0 to a bout 40% Ni to remain constant up to purr NiO, Inner layer capacitance and electrochemical (wet) surface area have also been derived from potentiometr ic titration curves. The results have been discussed in comparison with oth er few data in the literature. (C) 1998 Elsevier Science Ltd. All rights re served.