Department für Chemie, Universität zu Köln, Luxemburger Str. 116, D-50939 Köln, Germany.
Beilstein J Nanotechnol. 2012;3:75-81. doi: 10.3762/bjnano.3.9. Epub 2012 Jan 30.
In order to enhance the resistance of cobalt nanoparticles to oxidation in air, the impact of different stabilization strategies on the isothermal oxidation of particle dispersions and powders was kinetically investigated and compared to as-prepared particle preparations. A post-synthesis treatment with different alcohols was employed, and we also investigate the influence of two different polymer shells on the oxidation process. We found a parabolic decrease of the magnetization for all particle charges, indicating that the process is dominated by a diffusion of oxygen to the cobalt core and a radial growth of the oxide layer from the particle surface to the core. A significant deceleration of the oxidation process was observed for all alcohol-passivated particle preparations, and this resulted finally in a stagnation effect. The stabilizing effect increases in the sequence Co@OA/MeOH < Co@OA/EtOH < Co@OA/iPrOH. For polymer-coated particle preparations Co@PCL and Co@PS, the deceleration was even more pronounced. The results demonstrate that cobalt nanoparticles can effectively be protected against oxidation in order to improve their mid- to longterm stability.
为了提高空气中钴纳米粒子的抗氧化能力，我们从动力学角度研究并比较了不同稳定策略对颗粒分散体和粉末的等温氧化的影响，与制备好的粒子相比。我们采用了不同醇的后合成处理，还研究了两种不同聚合物壳对氧化过程的影响。我们发现所有粒子电荷的磁化率呈抛物线下降，这表明该过程主要受氧向钴核的扩散和氧化物层从粒子表面向核的径向生长控制。所有醇钝化粒子制备物的氧化过程都明显减缓，最终导致停滞效应。稳定效果按 Co@OA/MeOH < Co@OA/EtOH < Co@OA/iPrOH 的顺序增加。对于聚合物包覆的粒子制备物 Co@PCL 和 Co@PS，减缓作用更为明显。结果表明，钴纳米粒子可以有效地防止氧化，从而提高其中长期稳定性。
