物理化学学报 >> 2019, Vol. 35 >> Issue (6): 616-623.doi: 10.3866/PKU.WHXB201805082

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LaCoO3-TiO2纳米管阵列的构筑及可见光光催化性能

弓程1,2,向思弯1,2,张泽阳1,2,孙岚1,2,*(),叶陈清2,林昌健1   

  1. 1 厦门大学化学化工学院化学系,固体表面物理化学国家重点实验室,福建 厦门 361005
    2 宁德市师范学院,特色生物化工材料福建省重点实验室,福建 宁德 352100
  • 收稿日期:2018-05-29 录用日期:2018-07-17 发布日期:2018-10-31
  • 通讯作者: 孙岚 E-mail:sunlan@xmu.edu.cn
  • 基金资助:
    国家自然科学基金(21621091);广东省自然科学基金(2016A030313845)

Construction and Visible-Light-Driven Photocatalytic Properties of LaCoO3-TiO2 Nanotube Arrays

Cheng GONG1,2,Siwan XIANG1,2,Zeyang ZHANG1,2,Lan SUN1,2,*(),Chenqing YE2,Changjian LIN1   

  1. 1 State Key Laboratory for Physical Chemistry of Solid Surfaces, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian Province, P. R. China
    2 Fujian Provincial Key Laboratory of Featured Materials in Biochemical Industry, Ningde Normal University, Ningde 352100, Fujian Province, P. R. China
  • Received:2018-05-29 Accepted:2018-07-17 Published:2018-10-31
  • Contact: Lan SUN E-mail:sunlan@xmu.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(21621091);Guangdong Natural Science Foundation, China(2016A030313845)

摘要:

TiO2纳米管阵列具有较高的光催化活性,但可见光吸收弱,限制了其太阳能利用和环境应用。窄带隙的钙钛矿(ABO3)型氧化物能够吸收大范围波段的可见光,且稳定性高,但光催化活性低。本文首先采用溶胶-凝胶法合成了LaCoO3纳米颗粒,然后利用电泳沉积技术将LaCoO3纳米颗粒修饰于TiO2纳米管阵列表面,构筑了LaCoO3-TiO2纳米管阵列。扫描电子显微镜(SEM)、透射电子显微镜(SEM)、X射线衍射(XRD)和X射线光电子能谱(XPS)的表征结果显示溶胶-凝胶法合成的纳米颗粒为LaCoO3,其尺寸均匀,结晶度高,平均粒径约为100 nm。LaCoO3纳米颗粒与TiO2纳米管阵列之间的结合力好。紫外可见吸收光谱(DRS)显示,随着电泳沉积时间的延长,LaCoO3-TiO2纳米管阵列的吸收带边逐渐红移700 nm。可见光下光催化降解甲基橙(MO)的结果表明,电泳沉积15 min制得的LaCoO3-TiO2纳米管阵列对MO的光催化效率最高,其降解速率是相同条件下TiO2纳米管阵列的4倍。光致发光光谱和电化学阻抗谱证实LaCoO3纳米颗粒的负载有效地促进了光生电荷的分离和传输,可见光光催化活性明显增强。

关键词: LaCoO3, TiO2纳米管阵列, 可见光, 光催化, 甲基橙

Abstract:

TiO2 nanotube arrays (NTAs) have high photocatalytic activity; however, their weak visible light absorption limits their solar energy utilization and environmental application. Perovskite (ABO3)-type oxides with a narrow band gap can absorb visible light in a wide wavelength range and have excellent stability; however, their photocatalytic activity is relatively low. Coupling TiO2 NTAs with ABO3 to form heterojunctions is one of the most promising approaches to extend the optical absorption of TiO2 NTAs into the visible-light range and promote the separation rate of photogenerated electron–hole pairs. However, to date, constructing ABO3-TiO2 NTA heterostructured composites has been extremely challenging owing to the different crystallization temperatures of anatase TiO2 NTAs and ABO3. In this work, LaCoO3 nanoparticles were first synthesized using a sol-gel method. The as-prepared LaCoO3 nanoparticles were then modified on the surface of the TiO2 NTAs using an electrophoretic deposition technique, and a series of LaCoO3-TiO2 NTAs photocatalysts were thus constructed by controlling the deposition time. Results of the scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) demonstrated that the nanoparticles prepared through the sol-gel method were LaCoO3 with a uniform size and high crystallization. The average diameter of the LaCoO3 nanoparticles was 100 nm. The binding strength between the LaCoO3 nanoparticles and the TiO2 NTAs was strong. The UV-visible absorption spectra (diffuse reflectance spectroscopy; DRS) demonstrated that the absorption band edge of the LaCoO3-TiO2 NTAs was gradually red-shifted into the visible light region with the increase in electrophoretic time. The LaCoO3-TiO2 NTAs prepared by the electrophoretic deposition technique for 15 min exhibited a strong light absorption in the wide wavelength range from 250 to 700 nm, which was the same as that of the LaCoO3 nanoparticles loaded on a Ti foil. The results of the photocatalytic degradation of methyl orange (MO) under visible light irradiation demonstrated that the photocatalytic degradation rate of MO over LaCoO3-TiO2 NTAs was considerably higher than those of TiO2 NTAs and LaCoO3 nanoparticles loaded on a Ti foil. The LaCoO3-TiO2 NTAs prepared by the electrophoretic deposition technique for 15 min showed the highest photocatalytic degradation rate of MO, which was a four-fold enhancement compared to that of TiO2 NTs under the same conditions. The p-n heterojunctions between the LaCoO3 nanoparticles and the TiO2 nanotubes were responsible for the enhanced visible light photocatalytic activity. The results of the electrochemical impedance spectroscopy (EIS) and photoluminescence spectroscopy (PL) tests demonstrated that the loading of the LaCoO3 nanoparticles effectively promoted the separation and transport of photogenerated charges, thereby enhancing the visible light photocatalytic activity of the TiO2 NTAs.

Key words: LaCoO3, TiO2 nanotube arrays, Visible light, Photocatalysis, Methyl orange

MSC2000: 

  • O644