Synthesis of nanocrystalline SnO2 in supercritical water
Synthesis of nanocrystalline SnO2 in supercritical water
复制标题
超临界水合成纳米晶 SnO2
DOI：
10.1007/s11051-006-9171-9
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
J. Kozinski
中科院分区：
文献类型：
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作者：
Zhen Fang;H. Assaaoudi;Hanbai Lin;Xiaoming Wang;I. Butler;J. Kozinski
以0.1-0.4 M SnCl 4水溶液为原料，在385-415°C、30 MPa（停留时间38-106 s）的超临界水中，采用管式反应器合成了纳米SnO 2。转化率在53 - 81%之间，但当加入0.1M NaOH时增加到97.8%。通过TEM、拉曼、XRD、SEM、EDX和FT-IR等一系列独立的分析手段对纳米粒子进行了分析，得到纳米粒子的初始粒径约为3.7 nm。在450°C下煅烧2小时后，粒度增加至4 nm。弱的拉曼和XRD信号表明，颗粒具有低结晶度。所有的颗粒组成的Sn和O，证实了EDX光谱。晶体是四氢呋喃，如通过弱XRD光谱所证实的。在600°C下煅烧10 h后，粒径增加至9 nm，同时通过拉曼和XRD分析证实了高结晶度。所有晶体具有相同的结构，如TEM电子衍射图案所示。使用这种一步超临界水工艺，SnO 2纳米粒子可以方便地在流动反应器中在不到2分钟内连续生产。
Nanocrystalline SnO2was synthesized in supercritical water at 385–415°C and 30 MPa (38–106 s residence time) in a tubular flow reactor from an aqueous solution of 0.1–0.4 M SnCl4. The conversion rate was between 53 and 81%, but increased to 97.8% when 0.1 M NaOH was added. Nanoparticles were analyzed by a series of independent analytical techniques, including TEM, Raman, XRD, SEM, EDX and FT-IR. The initial size of the particles was about 3.7 nm. After calcination at 450°C for 2 h, the particle size increased to 4 nm. The particles were of low crystallinity, as indicated by the weak Raman and XRD signals. All particles were composed of Sn and O, as verified by the EDX spectra. The crystals were tetragonal, as confirmed by the weak XRD spectrum. After calcination at 600°C for 10 h, the particle size increased to 9 nm, while high crystallinity was confirmed by Raman and XRD analyses. All the crystals had the same structure, as indicated by TEM electron diffraction patterns. Using this one-step supercritical water process, nanoparticles of SnO2can be conveniently produced continuously in a flow reactor in less than 2 min.