Trushkina Yulia, Tai Cheuk-Wai, Salazar-Alvarez German
Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden.
Nanomaterials (Basel). 2019 Jul 12;9(7):1004. doi: 10.3390/nano9071004.
Maghemite nanoparticles with high surface area were obtained from the dehydroxylation of lepidocrocite prismatic nanoparticles. The synthesis pathway from the precursor to the porous maghemite nanoparticles is inexpensive, simple and gives high surface area values for both lepidocrocite and maghemite. The obtained maghemite nanoparticles contained intraparticle and interparticle pores with a surface area ca. 30 × 10 m/mol, with pore volumes in the order of 70 cm/mol. Both the surface area and pore volume depended on the heating rate and annealing temperature, with the highest value near the transformation temperature (180-250 °C). Following the transformation, in situ X-ray diffraction (XRD) allowed us to observe the temporal decoupling of the decomposition of lepidocrocite and the growth of maghemite. The combination of high-angle annular dark-field imaging using scanning transmission electron microscopy (HAADF-STEM) and surface adsorption isotherms is a powerful approach for the characterization of nanomaterials with high surface area and porosity.
具有高表面积的磁赤铁矿纳米颗粒是由纤铁矿棱柱形纳米颗粒脱羟基化得到的。从前体到多孔磁赤铁矿纳米颗粒的合成途径成本低廉、操作简单，并且纤铁矿和磁赤铁矿都具有高表面积值。所获得的磁赤铁矿纳米颗粒含有颗粒内和颗粒间孔隙，表面积约为30×10 m²/mol，孔体积约为70 cm³/mol。表面积和孔体积都取决于加热速率和退火温度，在转变温度（180 - 250°C）附近具有最高值。转变之后，原位X射线衍射（XRD）使我们能够观察到纤铁矿分解和磁赤铁矿生长的时间解耦。使用扫描透射电子显微镜（HAADF - STEM）的高角度环形暗场成像与表面吸附等温线相结合，是表征具有高表面积和孔隙率的纳米材料的有力方法。
