Hafnium-doped titania (Hf/Ti = 0.01; 0.03; 0.05) had been facilely synthesized via a template sol-gel method on carbon fibre. Physico-chemical properties of the as-synthesized materials were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis, scanning transmission electron microscopy, X-ray photoelectron spectroscopy, thermogravimetry analysis and Brunauer-Emmett-Teller measurements. It was confirmed that Hf4+ substitute in the Ti4+ sites, forming Ti1-x Hf x O2 (x = 0.01; 0.03; 0.05) solid solutions with an anatase crystal structure. The Ti1-x Hf x O2 materials are hollow microtubes (length of 10-100 µm, outer diameter of 1-5 µm) composed of nanoparticles (average size of 15-20 nm) with a surface area of 80-90 m2 g-1 and pore volume of 0.294-0.372 cm3 g-1. The effect of Hf ion incorporation on the electrochemical behaviour of anatase TiO2 in the Li-ion battery anode was investigated by galvanostatic charge/discharge and electrochemical impedance spectroscopy. It was established that Ti0.95Hf0.05O2 shows significantly higher reversibility (154.2 mAh g-1) after 35-fold cycling at a C/10 rate in comparison with undoped titania (55.9 mAh g-1). The better performance offered by Hf4+ substitution of the Ti4+ into anatase TiO2 mainly results from a more open crystal structure, which has been achieved via the difference in ionic radius values of Ti4+ (0.604 Å) and Hf4+ (0.71 Å). The obtained results are in good accord with those for anatase TiO2 doped with Zr4+ (0.72 Å), published earlier. Furthermore, improved electrical conductivity of Hf-doped anatase TiO2 materials owing to charge redistribution in the lattice and enhanced interfacial lithium storage owing to increased surface area directly depending on the Hf/Ti atomic ratio have a beneficial effect on electrochemical properties.

译文

:通过模板溶胶-凝胶法在碳纤维上容易地合成了掺af的二氧化钛(Hf / Ti = 0.01; 0.03; 0.05)。通过X射线衍射,拉曼光谱,扫描电子显微镜,能量色散X射线分析,扫描透射电子显微镜,X射线光电子能谱,热重分析和Brunauer-Emmett表征了所合成材料的物理化学性质。 -出纳员测量。确认在Ti4位上存在Hf4替代物,形成Ti1-x Hf
X
具有锐钛矿型晶体结构的O2(x == 0.01; 0.03; 0.05)固溶体。 Ti1-x Hf
X
O2材料是中空微管(长度为10-100μm,外径为1-5μm),由纳米颗粒(平均尺寸为15-20μnm)组成,表面积为80-90μm2μg-1,孔体积为0.294 -0.372 cm3 g-1。通过恒电流充/放电和电化学阻抗谱研究了Hf离子掺入对锐钛矿型TiO2在锂离子电池阳极中电化学行为的影响。已经确定,与未掺杂的二氧化钛(55.9 mAh g-1)相比,Ti0.95Hf0.05O2在以C / 10速率循环35倍后显示出更高的可逆性(154.2 mAh g-1)。 Hf4将Ti4替换为锐钛矿型TiO2所提供的更好性能,主要是由于晶体结构更开放,这是通过Ti4(0.604Å)和Hf4(0.71Å)的离子半径值的差异实现的。所得结果与先前公布的掺杂Zr4(0.72Å)的锐钛矿型TiO2的结果非常吻合。此外,由于Hf / Ti原子比直接取决于Hf / Ti原子比,由于在晶格中电荷的重新分布,改善了Hf掺杂的锐钛矿型TiO2材料的电导率以及由于增加了表面积而增加了界面锂存储。

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