| Recently, highly ordered micro/nano architectures have attracted much attention in the areas of materials due to their improved properties originating from their building blocks and potential applications in many fields. Copper selenides, as an important p-type semiconductor with band gaps 1.2-2.3 e V, can form in many stoichiometries(Cu Se, Cu2-xSe, Cu2 Se, Cu2Se3 and Cu5Se4) and phases(cubic, tetragonal, orthorhombic and monoclinic), which can be extensively used in photocatalysts, super ionic conductors and solar cells etc. They have been synthesized by many ways such as hydrothermal method, ultrasonic method, microwave method, solvent method etc. However, to the best of our knowledge, no report has touched on the synthesis of a speaking trumpet-like copper selenide microstructure with ultrathin nanosheet hierarchical structures. Nanostructured Ti O2 photocatalysts have received much attention due to their high photocatalytic activity, excellent chemical stability, low cost,nontoxicity and resistance to photocorrosion. Generally Ti O2 nanoparticles possess high specific surface areas(high activities), it can be easily separated from a multiphase system after photocatalytic reaction. Thus, research on Ti O2 NTA films has become a hot topic in recent years. In this paper, Cu Se film and Ti O2 nanotube array has been successfully prepared by easy mothods and studied their properties. The content includes:1. For the first time, highly ordered and uniform flower-like Cu2 Se microstruvture with nanosheet hierarchical structure has been synthesized, and the gas sensing property was studied. It is the most sensitive to acetone gas and responses very quickly. The response time is about 4 s, and the recovery time is about 5 s. Therefore, it can be a very good sensing material in the future.2. High-quality and ordered speaking trumpet-like Cu2 Se micro/nano architecture on a Cu foil substrate has been successfully prepared by simply laying a rod-like Cu(OH)2 precursor in a Se2-solution for 4 h at room temperature. Its formation mechanism was investigated on the basis of time-dependent morphology evolution.The results show that Ostwald ripening,transformation of precipitate and oriented growth and assembly of Cu2 Se nanocrystals are involved in the formation process of the speaking trumpet-like Cu2 Se micro/nano architecture.Its band gap is 2.03 e V.3. Well aligned Ti O2 nanotube array(NTA) has been successfully prepared by anodic oxidation method using fluoride based electrolyte in ethylene glycol solution with 3 vol.%H2O and 7 vol.% formamide. Anatase phase of Ti O2 NTA was obtained after heat treatment at400 °C for 3 h, which exhibits a good UV and visible light absorption capability. The band gap of the as-prepared Ti O2 NTA is 2.74 e V. This low band gap could be caused by Ti3+ sites(oxygen vacancies) as a role of the intermediate trap state formed in the process of calcination.A sub-band gap energy of 1.7 e V is also observed for this Ti O2 NTA, which is mainly attributed to the non-neglectable N-doping(9.87 At.%). Effects of the preparation parameters on tube lengths and diameters of the Ti O2 were investigated and series of samples with different lengths(similar diameters) and diameters(similar tube lengths) were fabricated.Applied voltage is found significantly influencing the tube diameters and lengths of the Ti O2 NTAs. However, a distinct enhancement in photodegradation rates was observed when the tube length was increased from 0.57 to 2.03 mm. Thus, the photocatalytic activity of the Ti O2 NTA can be enhanced by simply tuning the tube length and diameter in an appropriate range.The radical trapping experiments demonstrate that ×OH is the major active species responsible for photodegradation of Rh B. Besides, photogenerated holes also partially take part in the photodegradation reaction. |
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