高等学校化学学报 ›› 2021, Vol. 42 ›› Issue (8): 2509.doi: 10.7503/cjcu20210162

• 物理化学 • 上一篇    下一篇

Bi1-xFexVO4薄膜光阳极的制备及光电化学性能

唐定(), 衷水平   

  1. 福州大学紫金矿业学院, 福州 350108
  • 收稿日期:2021-03-10 出版日期:2021-08-10 发布日期:2021-08-05
  • 通讯作者: 唐定 E-mail:tang_ding@163.com
  • 基金资助:
    国家自然科学基金(21802113)

Preparation and Photoelectrochemical Performance of Bi1-xFexVO4 Thin Film Photoanodes

TANG Ding(), ZHONG Shuiping   

  1. College of Zijin Mining,Fuzhou University,Fuzhou 350108,China
  • Received:2021-03-10 Online:2021-08-10 Published:2021-08-05
  • Contact: TANG Ding E-mail:tang_ding@163.com
  • Supported by:
    the National Natural Science Foundation of China(21802113)

摘要:

采用一步滴涂法在掺氟二氧化锡(FTO)导电玻璃上制备了Bi1-xFexVO4(x=0, 0.05, 0.10, 0.25, 0.40)薄膜, 表征了其结构、 形貌、 光学以及光电化学方面的性质. 结果表明, 掺入Fe后Bi1-xFexVO4薄膜的光电流密度与 BiVO4薄膜相比均有所提高, 其中25% Fe-BiVO4薄膜表现出最优的光电化学性能. 在0.1 mol/L磷酸缓冲溶液(pH=7.0)中, 1.23 V(vs. RHE)电势下25% Fe-BiVO4薄膜的光电流密度为0.50 mA/cm2, 与BiVO4薄膜的0.15 mA/cm2相比提高了3倍多. 结合X射线衍射(XRD)、 拉曼光谱(Raman)和X射线光电子能谱(XPS)表征结果证实Fe3+以FeVO4的形式存在于Bi1-xFexVO4薄膜中, 形成了BiVO4/FeVO4复合物薄膜. 紫外-可见光谱(UV-Vis)结果显示, 所有Bi1-xFexVO4薄膜的禁带宽度均为2.4~2.5 eV. 25% Fe-BiVO4薄膜光电化学性能的提升主要归因于光生载流子转移效率(ηtrans)和分离效率(ηsep)的提高. 能级结构图表明, BiVO4和FeVO4之间可以形成Type Ⅱ型能级结构排列, 可以促进光生载流子的分离与转移, 是25% Fe-BiVO4薄膜光电化学性能提升的内在机理.

关键词: 光电化学分解水, 钒酸铋, 载流子表面复合, Type II异质结, 复合物薄膜

Abstract:

Herein, Bi1-xFexVO4x=0, 0.05, 0.10, 0.25, 0.40) thin films were prepared on fluorine-doped tin dioxide(FTO) conductive glasses by one-step drop-coating approach, and their structural, morphological, optical and photoelectrochemical(PEC) properties were characterized. It is found that Bi1-xFexVO4 thin films with Fe addition show the better PEC performance compared with BiVO4 thin film. At the potential of 1.23 V(vs. RHE), a highest photocurrent density of 0.50 mA/cm2 for water oxidation is obtained for 25% Fe-BiVO4(the actual Fe content is 22.5%) thin film in 0.1 mol/L potassium phosphate buffer solution(pH=7.0), which is three times higher than that of BiVO4 thin film. Combined with X-ray diffraction(XRD), Raman spectroscopy and X-ray photoelectron spectroscopy(XPS) analyses, it is confirmed that Fe3+ presents in form of FeVO4 in the Bi1-xFexVO4 thin films, thus actually a BiVO4/FeVO4 composite film is prepared. The UV-Vis measurements reveal that all the Bi1-xFexVO4 thin films exhibit an optical band gap of 2.4—2.5 eV. After eliminating the effort of iron-based OER catalysts, the improved PEC activity of 25% Fe-BiVO4 thin film could be attributed to the increment of charge transfer efficiency(ηtrans) and separation efficiency(ηsep), which is also verified by electrochemical impedance spectroscopy(EIS) tests. The flat band potentials of BiVO4 and FeVO4 thin films are determined to be 0.10 V and 0.42 V(vs. RHE) from Mott-Schottky measurements. Based on the measured optical band gap and flat band potential, a schematic diagram of band structure is plotted, and the result displays that a type Ⅱ band alignment is formed between BiVO4 and FeVO4, which could promote the separation and transfer of photogenerated electron-hole pairs. Therefore, the mechanism for the improved PEC performance of 25% Fe-BiVO4 thin film could be explained by favorable separation and transfer of carriers resulted from the type Ⅱ band alignment.

Key words: Photoelectrochemical water splitting, Bismuth vanadate, Carrier surface recombination, Type II heterojunction, Composite film

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