Hierarchical Fe2O3@WO3 nanostructures with ultrahigh specific surface areas: microwave-assisted synthesis and enhanced H2S-sensing performance
Hierarchical Fe2O3@WO3 nanostructures with ultrahigh specific surface areas: microwave-assisted synthesis and enhanced H2S-sensing performance
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DOI：
10.1039/c4ra10500a
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发表时间：
2015
期刊：
影响因子：
3.9
通讯作者：
L. Yin;Deliang Chen;M. Feng;Lianfang Ge;Dewei Yang;Zhan-Ke Song;B. Fan;Rui Zhang;G. Shao
中科院分区：
文献类型：
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作者：
L. Yin;Deliang Chen;M. Feng;Lianfang Ge;Dewei Yang;Zhan-Ke Song;B. Fan;Rui Zhang;G. Shao
采用微波加热原位生长法制备了Fe2O3纳米颗粒（NPs）和WO3单晶纳米片，合成了具有超高比面积的Fe2O3@WO3纳米复合材料。通过插层和拓扑化学转化途径制备了WO3纳米板，并通过异质成核在WO3表面原位生长了Fe2O3纳米粒子。为了进行比较，还开发了水浴加热（WH）工艺来合成Fe2O3@WO3纳米复合材料。采用x射线衍射（XRD）、x射线光电子能谱（XPS）、扫描电镜（SEM）和透射电镜（TEM）等技术对所得样品进行了表征。结果表明：在MH法制备的Fe2O3@WO3样品中，α-Fe2O3纳米粒子粒径范围在5 ~ 10 nm之间，均匀、紧密地固定在WO3纳米板表面；而在WH法制备的Fe2O3@WO3样品中，α-Fe2O3纳米粒子粒径和空间分布并不均匀；MH法制备的5wt%Fe2O3@WO3样品的BET比表面积高达1207 m2 g−1，是相应WO3纳米片（203 m2 g−1）的5.9倍。Fe2O3@WO3样品比表面积的显著增强应归因于分层结构，这使得聚集的多晶体的内部表面或界面通过卡屋结构完全成为外部表面，其中单层和断开的Fe2O3 NPs紧密地固定在WO3纳米板的表面上。研究了Fe2O3@WO3传感器的气敏性能。通过MH工艺制备的Fe2O3@WO3气体传感器在低温下对H2S具有较高的响应和选择性。5%Fe2O3@WO3样品在150°C时表现出最高的h2s感应响应。对10 ppm H2S的响应高达192，是wo3纳米片传感器的4倍。Fe2O3@WO3纳米复合材料气敏性能的提高可归因于成分的协同效应和具有超高比表面积的分层微结构。
Hierarchical Fe2O3@WO3 nanocomposites with ultrahigh specific areas, consisting of Fe2O3 nanoparticles (NPs) and single-crystal WO3 nanoplates, were synthesized via a microwave-heating (MH) in situ growth process. WO3 nanoplates were derived by an intercalation and topochemical-conversion route, and the Fe2O3 NPs were in situ grown on the WO3 surfaces via a heterogamous nucleation. The water-bath-heating (WH) process was also developed to synthesize a Fe2O3@WO3 nanocomposite for comparison purposes. The techniques of X-ray diffraction (XRD), X-ray photoelectron spectrum (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the samples obtained. The results show that α-Fe2O3 NPs with a size range of 5–10 nm are uniformly, tightly anchored on the surfaces of WO3 nanoplates in the Fe2O3@WO3 samples obtained via the MH process, whereas the α-Fe2O3 NPs are not uniform in particle-sizes and spatial distribution in the Fe2O3@WO3 samples obtained via the WH process. The BET surface area of the 5wt%Fe2O3@WO3 sample derived by the MH process is as high as 1207 m2 g−1, 5.9 times higher than that (203 m2 g−1) of the corresponding WO3 nanoplates. The dramatic enhancement in the specific surface area of the Fe2O3@WO3 samples should be attributed to the hierarchical microstructure, which makes the internal surfaces or interfaces in aggregated polycrystals be fully outside surfaces via a house-of-cards configuration, where the single-layered and disconnected Fe2O3 NPs are tightly anchored on the surfaces of the WO3 nanoplates. The gas-sensing properties of the Fe2O3@WO3 sensors were investigated. The gas-sensors based on the Fe2O3@WO3 obtained via the MH process show a high response and selectivity to H2S at low operating temperatures. The 5%Fe2O3@WO3 sample shows the highest H2S-sensing response at 150 °C. Its response to 10 ppm H2S is as high as 192, 4 times higher than that of the WO3-nanoplate sensor. The improvement in the gas-sensing performance of the Fe2O3@WO3 nanocomposites can be attributed to the synergistic effect in compositions and the hierarchical microstructures with ultrahigh specific surface areas.