一步水热合成铜纳米颗粒负载二氧化钛复合纳米管及其可见光催化活性(英文)

One-Step Hydrothermal Synthesis and Visible-Light Photocatalytic Activity of Ultrafine Cu-Nanodot-Modified TiO_2 Nanotubes

采用一步水热法合成了Cu纳米粒子负载二氧化钛纳米管材料. 利用透射电子显微镜(TEM)、X射线衍射仪(XRD)、能谱仪(EDS)等对材料的相组成、形貌以及形成过程进行了研究. 制得的Cu-TiO2复合纳米材料长度约为100nm, 直径10-15nm, 其上负载的Cu纳米粒子尺寸约为5nm. BET比表面积测试表明实验制备的Cu-TiO2复合纳米管的比表面积为154.67m2·g-1. 通过调节水热反应时间和钛前驱体种类, 研究了该复合纳米管材料的形成机制. 结果表明: 非晶态的钛源对于成功一步合成Cu-TiO2复合纳米管至关重要. 同时, 实验中观察到铜纳米粒子的尺寸随水热反应时间延长而减小(反奥氏陈化过程), 这一现象有助于纳米粒子的可控合成.紫外-可见吸收光谱表明该复合纳米管在350-800nm范围内有较强的吸收, 并在550-600nm范围观察到Cu的表面等离子激元吸收带. Cu-TiO2界面处形成的肖特基势垒有助于加快光生载流子的输运, 提高光生电子-空穴对的分离效率. 光催化实验表明Cu-TiO2复合纳米管在可见光下具有较高的催化活性.

One dimensional titanate nanotubes modified with copper nanospheres were synthesized through a facile one-step hydrothermal process. Transmission electron microscope （TEM）, X-ray diffraction （XRD）, and energy dispersive spectrometry （EDS） were used to monitor the changes in the morphology and phases during the hydrothermal process. The diameter of the Cu-TiO2 composite nanotubes was 10-15 nm and their lengths were ca 100 nm, the dimension of the covered Cu nanoparticles was about 5 nm. Brunauer-Emmett-Teller （BET） tests revealed the specific surface area of the Cu-TiO2 composite nanotubes to be 154.67 m2·g-1. The formation process and mechanism of the composite nanotubes were surveyed by adjusting the hydrothermal duration and titanium precursor. The results revealed that an amorphous titanium precursor is essential for the successful formation of this unique topography and phase composition. Anti-Ostwald ripening, a decrease in the dimensions of the copper nanospheres with hydrothermal time, was observed in the TEM images, which is of benefit to helps keep the particles on the nanoscale. The UV-Vis spectrum of the as-prepared material exhibits a strong absorption at 350-800 nm in the visible band compared with commercial TiO2 nanopowders. The plasmonic absorption of metallic copper particles between 550 and 600 nm is seen in the UV-Vis spectrum. Schottky barriers between copper-TiO2 interfaces make this kind of material a potential agent in speeding up electron transport rates and slowing recombination rates. Photocatalytic experiments demonstrated this unique Cu-TiO2 composite nanotube material has a high photocatalytic activity under visible-light irradiation.