Preparation and characterization of NiCo_2O_4 fibre by coordination coprecipitation-thermal decomposition method

摘要

The spinel NiCo_2O_4 fibers with diameter less than lum were prepared by thermal decomposition, using complex nickel-cobalt oxalate containing ammonia as precursor, which were obtained by coordination coprecipitation techinique. The effects of different Ni/Co ratios, decomposition temperature and decomposition time on the phase constituent of nickel-cobalt oxides were addressed in detail. The crystallinity, purity, and surface morphology of the as-prepared NiCo_2O_4 fibers were investigated by XRD, IR, SEM, respectively. Finally, structure of nickel cobaltite spinel examined by X-ray absorption spectroscopy (XPS) indicates, as expected, that Ni occupies the octahedral sites of the spinel structure while Co occupies both tetrahedral and octahedral sites. The result of the surface examination by xps shows that the surface composition is different from nominal bulk composition.