Unusual transient stabilization with stabilizers and morphology of Co-nanoparticles

Abstract

Abstract Upon addition of sodium borohydride to a solution of cobalt nitrate, a transient species appears within the time of mixing, which is stable for some time ca. 10 min. The molar ratios of reactants (Co2+ ions and sodium borohydride), presence of stabilizer, ageing of an aqueous NaBH4 solution, mixing order of stabilizers sodium dodecyl sulfate (SDS), n-hexadecyltrimethylammonium bromide (CTAB), and poly(vinyl) alcohol (PVA) and reactants have immense influence on the stabilization of short-lived transient. Decomposition rate constant of transient have been determined (kobs = 0.76, 4.2, 4.9 × 10−4 s−1 for SDS, PVA and no stabilizer). The complex formation constant, KC and difference in absorption coefficients, Δϵ between SDS and Co2+ ions were found to be 2.4 × 10−2 mol−1 dm3 and 2298 mol−1 dm3 cm−1, respectively. The characteristics of the Co-nanoparticles were also studied using energy-dispersive spectroscopy (EDX), scanning electron microscopy (SEM) and transmission electron microscope (TEM). EDX spectrum XRD confirmed the presence of an elemental sulphur signal along with cobalt without any peaks of other impurities.