材料科学
X射线光电子能谱
高分辨率透射电子显微镜
光电流
介电谱
扫描电子显微镜
线性扫描伏安法
可见光谱
拉曼光谱
循环伏安法
石墨烯
化学工程
纳米技术
分析化学(期刊)
透射电子显微镜
光电子学
电化学
复合材料
化学
电极
光学
物理化学
工程类
物理
色谱法
作者
Qi Wang,Naxin Zhu,Enqin Liu,Chenlu Zhang,John C. Crittenden,Yi Zhang,Yanqing Cong
标识
DOI:10.1016/j.apcatb.2016.11.046
摘要
Visible-light active Fe2O3-GQDs/NF-TiO2 composite films were fabricated via sequential electro-deposition and electro-oxidation processes. The prepared photocatalytic films were extensively characterized using scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The results revealed that graphene quantum dots (GQDs) and α-Fe2O3 particles were simultaneously deposited onto the surface of N and F co-doped TiO2 (NF-TiO2) simply using a graphite sheet instead of a Pt sheet as anode in the electro-deposition process. The NF-TiO2 substrate obtained by calcining TiO2 nanotubes (TiO2-NTs) in the presence of NH4F displayed pyramid shapes with dominant (101) facets. Linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and Mott-Schottky (M-S) plots indicated that the generation, separation and transfer of photogenerated charges were greatly enhanced on the novel composite. The photocurrent density of Fe2O3-GQDs/NF-TiO2 was 4.2 times that on Fe2O3/TiO2-NTs at 0.5 V vs. Ag/AgCl under visible light irradiation. For the photoelectrocatalytic (PEC) reduction of Cr(VI) using Fe2O3-GQDs/NF-TiO2 as photoanode with a Ti sheet as cathode, substantially enhanced activity was achieved due to the combined effect of visible-light-active components (α-Fe2O3 and NF-TiO2) and excellent electron mediator (GQDs). The calculated reduction rate constant was 7 times that obtained on Fe2O3/TiO2-NTs film. Furthermore, both the long-time photocurrent and cyclic PEC reduction of Cr(VI) indicated good stability of the composite film.
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