Size-controlled gold nanoparticles on octahedral anatase particles as efficient plasmonic photocatalyst.
Size-controlled gold nanoparticles on octahedral anatase particles as efficient plasmonic photocatalyst.
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DOI：
10.1016/j.apcatb.2017.01.043
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发表时间：
2017-06-05
期刊：
影响因子：
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通讯作者：
Kowalska E
中科院分区：
文献类型：
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作者：
Wei Z;Rosa L;Wang K;Endo M;Juodkazis S;Ohtani B;Kowalska E
金修饰的八面体纳米粒子（Au/OAPs）具有增强的光催化活性。结构/晶格缺陷作为金纳米颗粒的成核位点。在各种空穴和电子清除剂存在下通过光沉积方法制备尺寸可控的金纳米颗粒。随着金纳米颗粒尺寸的增加，可见光催化活性增强。通过3D-FDTD模拟的较大金纳米颗粒的等离子体共振的强增强。采用超声-水热反应法制备八面体纳米粒子，并通过光沉积法在其表面修饰2wt%的金。通过改变超声波处理时间和超声波处理时间等工艺条件，可以得到不同理化性质和形态的OAP产品。利用X射线衍射（XRD）、扫描透射电镜（STEM）、X射线光电子能谱（XPS）和漫反射光谱（DRS）对Au/OAPs样品进行了表征。分别在有氧和厌氧条件下，以乙酸分解（CO2体系）和甲醇脱氢（H2体系）为反应体系，在紫外光照射下，以异丙醇氧化为反应体系，测试了其光催化活性。在Ar气氛下，所有OAP样品的金的光沉积都非常快（0.5-10 min），并且电子陷阱（Ep）含量与形成金纳米颗粒（NPs）的诱导期之间的明确相关性表明，二氧化钛样品中的Ep是二氧化钛表面上金光沉积快速的关键因素。结果发现，更好的二氧化钛的形态（更大的含量的刻面颗粒）导致形成较大的金纳米颗粒，而小的金纳米颗粒沉积在结构缺陷。用金纳米颗粒修饰OAP导致光催化活性的显著增强，例如，1.5（CO2体系）、7.7（H2体系），甚至在维斯光照射下超过40。研究发现，二氧化钛和金的性质对于所得的光催化活性至关重要，但由于当光催化剂制备条件（US-HT）改变时，所有结构性质同时改变，因此无法获得一种结构/物理性质与光催化活性之间的直接相关性。因此，通过改进的光沉积方法，控制尺寸的金纳米颗粒沉积在具有最佳形貌的OAP产物上。可见光下的光催化活性和金纳米颗粒的尺寸之间的明确相关性表明，金的性质是决定性的可见光活性，而不是二氧化钛的性质。3D-FDTD模拟证实，金纳米颗粒尺寸的增加导致具有场增强的扩展表面积。
Gold-modified octahedral anatase particles (Au/OAPs) with enhanced photocatalytic activity. Structural/lattice defects as nucleation sites for gold NPs. Size-controllable gold NPs by photodeposition method in the presence of various hole and electron scavengers. Enhanced vis-photocatalytic activity with an increase in gold NPs’ size. Strong enhancement of plasmon resonance for larger gold NPs by 3D-FDTD simulations. Octahedral anatase particles (OAPs), prepared by ultrasonication-hydrothermal reaction (US-HT), were modified with 2 wt% of gold by photodeposition. Conditions of US-HT process such as durations of US and durations of HT were varied to obtain OAPs products different by physicochemical and morphological properties. Au/OAPs samples were characterized by X-ray diffraction (XRD), scanning transmission electron microscopy (STEM), X-ray photoelectron spectroscopy (XPS) and diffuse reflectance spectroscopy (DRS). The photocatalytic activity was tested under UV irradiation for decomposition of acetic acid (CO2 system) and dehydrogenation of methanol (H2 system) under aerobic and anaerobic conditions, respectively, and for oxidation of 2-propanol under visible light irradiation. Photodeposition of gold was very fast for all OAPs samples (0.5–10 min) under Ar atmosphere, and the clear correlation between the content of electron traps (ETs) and the induction period, during which nanoparticles (NPs) of gold are formed, indicates that ETs in titania samples are a key-factor for rapidity of gold photodeposition on titania surface. It was found that better morphology of titania (larger content of faceted particles) resulted in formation of larger gold NPs, while small gold NPs were deposited on structural defects. Modification of OAPs with gold NPs resulted in significant enhancement of photocatalytic activity, being e.g., 1.5 (CO2 system), 7.7 (H2 system), and even more than 40 under vis irradiation. It was found that both the properties of titania and gold are crucial for resultant photocatalytic activity, but a direct correlation between one structural/physical property and photocatalytic activity could not be obtained since all structural properties changed simultaneously when conditions of photocatalyst preparation (US-HT) were changed. Therefore, gold NPs of controlled sizes were deposited on OAPs product with the best morphology by modified photodeposition method. Clear correlation between photocatalytic activity under visible light and the size of gold NPs indicates that gold properties are decisive for visible light activity rather than titania properties. 3D-FDTD simulations confirm that an increase in the size of gold NPs results in extended surface areas with field enhancement.