Jendrzej Sandra, Gökce Bilal, Amendola Vincenzo, Barcikowski Stephan
Technical Chemistry I and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Universitaetsstr. 7, 45141 Essen, Germany.
Department of Chemical Sciences, Università di Padova, 1 Via Marzolo, I-35131 Padova, Italy.
J Colloid Interface Sci. 2016 Feb 1;463:299-307. doi: 10.1016/j.jcis.2015.10.032. Epub 2015 Oct 22.
Unintended post-synthesis growth of noble metal colloids caused by excess amounts of reactants or highly reactive atom clusters represents a fundamental problem in colloidal chemistry, affecting product stability or purity. Hence, quantified kinetics could allow defining nanoparticle size determination in dependence of the time. Here, we investigate in situ the growth kinetics of ps pulsed laser-fragmented platinum nanoparticles in presence of naked atom clusters in water without any influence of reducing agents or surfactants. The nanoparticle growth is investigated for platinum covering a time scale of minutes to 50days after nanoparticle generation, it is also supplemented by results obtained from gold and palladium. Since a minimum atom cluster concentration is exceeded, a significant growth is determined by time resolved UV/Vis spectroscopy, analytical disc centrifugation, zeta potential measurement and transmission electron microscopy. We suggest a decrease of atom cluster concentration over time, since nanoparticles grow at the expense of atom clusters. The growth mechanism during early phase (<1day) of laser-synthesized colloid is kinetically modeled by rapid barrierless coalescence. The prolonged slow nanoparticle growth is kinetically modeled by a combination of coalescence and Lifshitz-Slyozov-Wagner kinetic for Ostwald ripening, validated experimentally by the temperature dependence of Pt nanoparticle size and growth quenching by Iodide anions.
反应物过量或高活性原子团簇导致的贵金属胶体合成后意外生长是胶体化学中的一个基本问题，会影响产品的稳定性或纯度。因此，定量动力学可以根据时间来确定纳米颗粒的尺寸。在此，我们原位研究了在水中裸原子团簇存在下，ps脉冲激光破碎的铂纳米颗粒的生长动力学，且没有任何还原剂或表面活性剂的影响。研究了纳米颗粒生成后数分钟至50天时间范围内铂纳米颗粒的生长情况，同时也补充了金和钯的相关结果。由于超过了最小原子团簇浓度，通过时间分辨紫外/可见光谱、分析盘式离心、zeta电位测量和透射电子显微镜确定了显著的生长。我们认为原子团簇浓度会随时间降低，因为纳米颗粒的生长是以原子团簇为代价的。激光合成胶体早期阶段（<1天）的生长机制通过快速无障碍聚结进行动力学建模。延长的缓慢纳米颗粒生长通过聚结和奥斯特瓦尔德熟化的 Lifshitz-Slyozov-Wagner 动力学相结合进行动力学建模，并通过铂纳米颗粒尺寸的温度依赖性和碘离子对生长的猝灭进行了实验验证。
