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本文以乙二醇为诱导剂通过电化学沉积法成功合成了球粒状及棒状纳米赤铁矿。X射线衍射光谱(XRD)和Raman光谱结果表明,球粒状赤铁矿粒径20±5 nm;棒状赤铁矿截面直径约20 nm,长90±10 nm;二者物相皆为单一均匀的赤铁矿。紫外-可见吸收光谱显示两种赤铁矿在300~550 nm范围内均有较好吸收,Tauc方程计算球粒状和棒状赤铁矿禁带宽度分别为2.00 e V和1.99 e V。Mott-Schottky拟合结果表明1 M KOH溶液体系中,棒状赤铁矿载流子浓度为1.95×1021cm-3,高于球粒状赤铁矿(3.16×1020cm-3)。进一步的光电化学实验表明:0.6 V(vs.Ag/Ag Cl)电势下棒状赤铁矿光照下电流密度较暗电流提升550%,球粒状赤铁矿电流密度提升77%。研究证实,赤铁矿形貌对其半导体特性及光电化学特性有影响,且棒状赤铁矿电极表现出更好的可见光响应特性,具有更佳的光电催化潜力。
In this paper, ethylene glycol as an inducing agent by electrochemical deposition method successfully synthesized spherical and rod-shaped nano-hematite. The results of X-ray diffraction (XRD) and Raman spectroscopy show that the particle size of spheroidal hematite is 20 ± 5 nm, the cross-section of rod-shaped hematite is about 20 nm and the length is 90 ± 10 nm. Both phases are single uniform Hematite. The UV-Vis absorption spectra showed that both hematites were well absorbed in the range of 300-550 nm. The Tauc equation calculated the forbidden band widths of spheroidal and rod-shaped hematite to be 2.00 eV and 1.99 eV, respectively. The Mott-Schottky fitting results showed that the carrier concentration of rod-shaped hematite was 1.95 × 1021 cm-3 in 1 M KOH solution system, higher than that of spheroidal hematite (3.16 × 1020 cm-3). Further photoelectrochemical experiments show that the current density of bar-like hematite increases by 550% under the illumination of 0.6 V (vs.Ag/AgCl), and the current density of spheroidal hematite increases by 77%. The results show that the morphology of hematite has an influence on its semiconductor properties and photoelectrochemical properties, and the rod-shaped hematite electrode exhibits better visible light response and better photocatalytic potential.