Park DongKook, Lee Man Sig
Green Materials & Processes Group, Korea Institute of Industrial Technology (KITECH) 55, Jongga-ro, Jung-gu Ulsan Republic of Korea
RSC Adv. 2019 Jan 23;9(6):3203-3207. doi: 10.1039/c8ra09738k. eCollection 2019 Jan 22.
Tin oxide (SnO) nanowires are produced by the calcination of tin glycolate (SnCHO) nanowires, which are synthesized with tin oxalate (SnCO) and ethylene glycol the so-called polyol process. In this study, the growth mechanism of SnCHO nanowires was investigated by monitoring the synthesis using scanning and transmission electron microscopy. The length and diameter of the nanowires were 9.25 μm and 0.37 μm, respectively; the former increased at a rate of 1.85 μm h but the latter did not increase over time. Fourier-transform IR spectroscopy showed that the nanowires were composed of SnCHO instead of SnCO. Changes in the components of the reaction solution were also confirmed by H NMR, C NMR, and high-performance liquid chromatography. SnCHO was formed by the substitution of the oxalate coordinated to tin by ethylene glycolate, which was produced by the deprotonation of ethylene glycol. In this reaction, oxalate gradually changed to formic acid and carbon dioxide, and SnCHO grew as a nanowire through O-Sn-O bond formation. In addition, when ethylene glycol was mixed with 1,2-propanediol, branched SnCHO nanowires were formed. The branching was due to the interference of the methyl group of 1,2-propanediol with the growth of bundle-type nanowires. The branched nanowires had a higher surface area-to-mass ratio than the bundled ones based on dispersion measurements. Knowledge of the growth mechanism and reaction conditions that affect morphology would be valuable in modifying the physical and electrical properties of metal oxide nanowires.
氧化锡（SnO）纳米线是通过对乙醇酸亚锡（SnCHO）纳米线进行煅烧制备而成的，而SnCHO纳米线是采用草酸亚锡（SnCO）和乙二醇通过所谓的多元醇法合成的。在本研究中，通过使用扫描电子显微镜和透射电子显微镜监测合成过程，对SnCHO纳米线的生长机制进行了研究。纳米线的长度和直径分别为9.25μm和0.37μm；前者以1.85μm/h的速率增加，但后者并未随时间增加。傅里叶变换红外光谱表明，纳米线由SnCHO而非SnCO组成。反应溶液成分的变化也通过氢核磁共振、碳核磁共振和高效液相色谱得到了证实。SnCHO是由乙醇酸根取代与锡配位的草酸根形成的，乙醇酸根是由乙二醇去质子化产生的。在该反应中，草酸根逐渐转变为甲酸和二氧化碳，SnCHO通过形成O-Sn-O键生长为纳米线。此外，当乙二醇与1,2-丙二醇混合时，会形成分支状的SnCHO纳米线。分支是由于1,2-丙二醇的甲基对束状纳米线生长的干扰。基于分散测量，分支状纳米线的比表面积高于束状纳米线。了解影响形态的生长机制和反应条件对于改变金属氧化物纳米线的物理和电学性质具有重要价值。
