Functional Nanomaterials Laboratory and Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences (CAS), Zhongguancun Beiyitiao 2, Haidianqu, Beijing 100190, China.
Anal Chim Acta. 2010 Feb 5;659(1-2):266-73. doi: 10.1016/j.aca.2009.11.040. Epub 2009 Nov 24.
In this work, peculiar porous alpha-Fe(2)O(3) nanospheres were fabricated by a glycine-assisted hydrothermal method. They have large mesopores (ca. 10nm) in the core and small mesopores (<4 nm) in the shell. To our best knowledge, there have been so far no reports on the synthesis of such peculiar porous alpha-Fe(2)O(3) nanospheres. X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and transmission electron microscopy were employed to characterize the obtained Fe(2)O(3) nanospheres. Effects of preparation conditions, such as reactants, reaction temperature and reaction duration, were investigated on the morphology and structure of Fe(2)O(3) nanospheres. It was shown that the morphology and structure could be readily controlled by the time and temperature of hydrothermal treatment. The formation mechanism was proposed based on experimental results, which shows that glycine molecules play an important role in the formation of the morphology and porous structure of alpha-Fe(2)O(3). The alpha-Fe(2)O(3) porous nanospheres were used as gas sensing layer, and exhibited excellent gas-sensing properties to ethanol in terms of response and selectivity. The sensors showed good reproducibility and stability as well as short response (9 s) and recovery time (43 s) even at an ethanol concentration as low as 50 ppm. The gas-sensing properties of porous alpha-Fe(2)O(3) nanospheres are also significantly better than those of previously reported Fe(2)O(3) nanoparticles (ca. 30 nm). The sensitivity of the former is over four times higher than that of the latter at varied ethanol concentrations. The gas-sensing mechanism was discussed in details. Both fast response and steady signal make these peculiar nanostructures a promising candidate for ethanol detection.
在这项工作中，通过甘氨酸辅助水热法制备了具有独特多孔α-Fe(2)O(3)纳米球。它们具有较大的中孔（约 10nm）核和较小的壳层中孔（<4nm）。据我们所知，目前还没有关于合成这种特殊多孔α-Fe(2)O(3)纳米球的报道。采用 X 射线衍射、扫描电子显微镜、能谱和透射电子显微镜对所得 Fe(2)O(3)纳米球进行了表征。考察了反应物、反应温度和反应时间等制备条件对 Fe(2)O(3)纳米球形貌和结构的影响。结果表明，通过水热处理的时间和温度可以很容易地控制形貌和结构。根据实验结果提出了形成机理，表明甘氨酸分子在α-Fe(2)O(3)的形貌和多孔结构形成中起着重要作用。将α-Fe(2)O(3)多孔纳米球用作气敏层，在乙醇方面表现出优异的气敏性能，包括响应和选择性。传感器即使在低至 50ppm 的乙醇浓度下也表现出良好的重现性和稳定性以及较短的响应（9s）和恢复时间（43s）。多孔α-Fe(2)O(3)纳米球的气敏性能也明显优于以前报道的 Fe(2)O(3)纳米颗粒（约 30nm）。在不同的乙醇浓度下，前者的灵敏度比后者高四倍以上。详细讨论了气敏机理。快速响应和稳定信号使这些特殊的纳米结构成为乙醇检测的有前途的候选材料。
