Construction and Visible-Light-Driven Photocatalytic Properties of LaCoO3-TiO2 Nanotube Arrays
Construction and Visible-Light-Driven Photocatalytic Properties of LaCoO3-TiO2 Nanotube Arrays
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DOI：
10.3866/pku.whxb201805082
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发表时间：
2019
影响因子：
10.9
通讯作者：
Cheng Gong;厦门 sup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;Siwan Xiang;Z. Zhang;Lan Sun;Chenqing Ye;Changjian Lin;宁德 sup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
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文献类型：
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作者：
Cheng Gong;厦门 sup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;Siwan Xiang;Z. Zhang;Lan Sun;Chenqing Ye;Changjian Lin;宁德 sup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
TiO 2纳米管阵列（NTAs）具有很高的光催化活性，但其对可见光的弱吸收限制了其在太阳能利用和环境保护方面的应用。具有窄带隙的过氧物（ABO 3）型氧化物可以吸收宽波长范围内的可见光，并且具有优异的稳定性;然而，它们的光催化活性相对较低。将TiO 2 NTA与ABO 3偶联形成异质结是将TiO 2 NTA的光吸收扩展到可见光范围并提高光生电子-空穴对分离速率的最有前途的方法之一。然而，到目前为止，构建ABO 3-TiO 2 NTA异质结构复合材料一直是极具挑战性的，由于不同的结晶温度的TiO 2 NTA和ABO 3。在这项工作中，LaCoO 3纳米粒子首先使用溶胶-凝胶法合成。然后采用电泳沉积技术将LaCoO 3纳米粒子修饰在TiO 2 NTAs表面，通过控制沉积时间制备了一系列LaCoO 3-TiO 2 NTAs光催化剂。扫描电子显微镜（SEM）、透射电子显微镜（TEM）、X射线衍射（XRD）和X射线光电子能谱（XPS）分析结果表明，溶胶-凝胶法制备的LaCoO 3纳米粒子尺寸均匀，结晶度高。LaCoO 3纳米颗粒的平均直径为100 nm。LaCoO 3纳米颗粒与TiO 2纳米TAs之间的结合强度较强。紫外-可见吸收光谱（漫反射光谱; DRS）表明，随着电泳时间的增加，LaCoO 3-TiO 2纳米管的吸收带边逐渐红移到可见光区。电泳沉积15 min制备的LaCoO 3-TiO 2纳米管在250 ~ 700 nm的宽波长范围内具有较强的光吸收，与钛片负载的LaCoO 3纳米粒子的光吸收相同。可见光下橙子（MO）的光催化降解结果表明，LaCoO 3-TiO 2纳米复合材料的光催化降解率明显高于TiO 2纳米复合材料和负载于Ti箔上的LaCoO 3纳米颗粒。电泳沉积15 min制备的LaCoO 3-TiO 2 NTAs对MO的光催化降解率最高，与相同条件下的TiO 2 NTs相比，光催化降解率提高了4倍。LaCoO 3纳米颗粒和TiO 2纳米管之间的p-n异质结是增强可见光催化活性的原因。电化学阻抗谱（EIS）和光致发光光谱（PL）测试结果表明，LaCoO 3纳米粒子的负载有效地促进了光生电荷的分离和传输，从而提高了TiO 2纳米管的可见光光催化活性。
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.