Yang Yu, Cao Minhua, Hu Changwen, Guo Yihang, Wang Enbo
Institute of Polyoxometalate Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun, 130024, People's Republic of China.
J Nanosci Nanotechnol. 2004 Sep;4(7):833-7. doi: 10.1166/jnn.2004.091.
It was demonstrated that Keggin-type polyoxometalates nanorods (POMs-nanorods) were prepared from a solution containing a surfactant polyethylene glycol (PEG), when heteropolyanions X(n+)M12O40 (X(n+) = P5+ and Si4+; M = W and Mo) were precipitated by ammonia ion obtained by hydrolysis of urea at 373 K. In this method, PEG was used as a template and ammonia ion (NH4+) was a counterion. In an oil bath kept at 373 K without stirring, three kinds of ammonium salts of POMs, i.e., (NH4)3PW12O40, (NH4)4SiW12O40, and (NH4)3PMo12O40 nanorods were obtained. The POMs-nanorods were characterized by transmission electron microscopy (TEM), selected area electron diffraction (SAED), infrared spectra (IR), inductively coupled plasma atomic emission spectrometry (ICP-AES) and X-ray powder diffraction (XRD). TEM showed that nanorods were 0.5-1.5 microm in length, and 50-150 nm in diameter. The results of IR, ICP-AES and XRD proved the existence of Keggin structure. The formation process of POMs-nanorods, (NH4)(8-n) X(n+)M12O40 (X(n+) = P5+ and Si4+; M = W and Mo) in a H2O/PEG system was discussed.
结果表明，当通过尿素在373K水解得到的铵离子使杂多阴离子X(n+)M12O40（X(n+) = P5+和Si4+；M = W和Mo）沉淀时，可从含有表面活性剂聚乙二醇（PEG）的溶液中制备出Keggin型多金属氧酸盐纳米棒（POMs-纳米棒）。在该方法中，PEG用作模板，铵离子（NH4+）作为抗衡离子。在373K的油浴中不搅拌，得到了三种POMs的铵盐，即(NH4)3PW12O40、(NH4)4SiW12O40和(NH4)3PMo12O40纳米棒。通过透射电子显微镜（TEM）、选区电子衍射（SAED）、红外光谱（IR）、电感耦合等离子体原子发射光谱法（ICP-AES）和X射线粉末衍射（XRD）对POMs-纳米棒进行了表征。TEM显示纳米棒长度为0.5 - 1.5微米，直径为50 - 150纳米。IR、ICP-AES和XRD的结果证明了Keggin结构的存在。讨论了在H2O/PEG体系中POMs-纳米棒(NH4)(8-n) X(n+)M12O40（X(n+) = P5+和Si4+；M = W和Mo）的形成过程。
