Efficient charge separation and photooxidation on cobalt phosphate-loaded TiO2 mesocrystal superstructures
Efficient charge separation and photooxidation on cobalt phosphate-loaded TiO2 mesocrystal superstructures
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DOI：
10.1039/c3ta14319h
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发表时间：
2014-02
影响因子：
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通讯作者：
T. Tachikawa;Peng Zhang;Zhenfeng Bian;T. Majima
中科院分区：
文献类型：
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作者：
T. Tachikawa;Peng Zhang;Zhenfeng Bian;T. Majima
开发基于半导体材料的高效光催化剂用于有机合成、燃料产生和环境净化是当前研究和各种工业的中心主题。在这项研究中，我们提出了一种新的策略，提高光催化剂的光氧化活性相结合的金属氧化物超结构和氧/氢释放的助催化剂。选择磷酸钴（CoPi）和Pt纳米颗粒作为模型助催化剂，并将其光化学沉积在TiO 2介晶上。通过整体平均和单颗粒光谱显微镜对复合材料的结构和反应动力学进行了深入研究。时间分辨漫反射和电子自旋共振光谱测量表明，光生空穴在TiO 2中转移到Co物种CoPi紫外光照射后。用荧光染料探针测试了复合材料的光氧化性能。结果表明，CoPi负载的TiO 2介晶具有比普通TiO 2更高的光催化活性，Pt纳米粒子的引入进一步提高了介晶的光催化活性。单晶上的原位荧光成像提供了关于反应位点的位置和产物分子的扩散的信息。因此，通过介晶超结构中的各向异性电子流定制的助催化剂的位点特异性改性显著地延迟了空穴和电子之间的电荷复合，从而导致增强的（高达约300倍）光氧化活性。
Development of efficient photocatalysts based on semiconductor materials for organic synthesis, fuel generation, and environmental purification is a central theme in current research and various industries. In this study, we propose a novel strategy for improving the photooxidation activity of photocatalysts by combining metal oxide superstructures and oxygen/hydrogen-evolving co-catalysts. Cobalt phosphate (CoPi) and Pt nanoparticles were selected as model co-catalysts and photochemically deposited on anatase TiO2 mesocrystals. The structures and reaction dynamics of the composites were thoroughly studied by ensemble-averaged and single-particle spectro-microscopies. Time-resolved diffuse reflectance and electron spin resonance spectroscopy measurements revealed that photogenerated holes in TiO2 are transferred to the Co species in CoPi upon UV light irradiation. The photooxidation properties of the composites were tested using fluorescence dye probes. It was found that CoPi-loaded TiO2 mesocrystals had higher activity than standard TiO2 photocatalysts, and their activity was further enhanced by introducing Pt nanoparticles on specific surfaces. In situ fluorescence imaging on a single crystal provides information on the location of reactive sites and the diffusion of product molecules. Consequently, the site-specific modification of co-catalysts tailored by anisotropic electron flow in the mesocrystal superstructures significantly retarded the charge recombination between the holes and electrons, thereby resulting in enhanced (up to approximately 300 times) photooxidation activity.