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TiO_2因其毒性低、稳定性高、制备成本低廉而获得广泛应用,特别是作为光催化剂在降解环境污染物方面受到了广泛关注;然而,纯TiO_2较大的光生载流子复合率和较宽的带隙限制了其应用.元素掺杂作为一种拓宽光催化剂光吸收能力的方法广泛应用于各种光催化剂的修饰改性,而两种具有光催化性能的TiO_2相共存则能有效抑制光生载流子的复合,因此采取合适的方法有效利用这两种TiO_2改性的方法制备得到更具实际应用潜质的光催化剂具有一定的可行性.本文通过简单的溶胶-凝胶过程向锐钛矿相与金红石相组成的混相TiO_2中共掺杂碳和钇得到了一种活性较高的可见光响应光催化剂.采用粉末X射线衍射、拉曼光谱、X射线光电子能谱和透射电镜等表征手段研究了碳和钇掺杂对TiO_2结构的影响,发现碳掺杂有利于金红石相的形成且材料具有更大的晶粒尺寸,钇掺杂则有利于锐钛矿相的形成且能细化材料的晶粒尺寸,提高材料的比表面积,导致材料更好的光催化活性.材料在30 W荧光灯光照条件下的光催化降解亚甲基蓝(MB)性能的研究显示,C-Y-TiO_2样品具有比单掺杂和未掺杂样品更高的光催化活性,其顺序为C-Y-TiO_2>Y-TiO_2>C-TiO_2>TiO_2≈P25.此外,降解反应动力学研究表明C-Y-TiO_2样品光降解MB的速率是未掺杂样品在相同条件下降解速率的3.5倍.不同钇掺杂含量样品的结构和光催化降解MB的研究结果表明,钇掺杂显著促进了锐钛矿相TiO_2的形成.这说明钇可能仅掺杂进入锐钛矿相,因此合适的钇掺杂量才能有效形成最优化的光催化性能的混相TiO_2.不同热处理温度下获得的样品的光降解MB特性也表明,一定的热处理温度有利于合适的锐钛矿相和金红石相的组成,从而有利于相间的协同效应.紫外-可见光谱和荧光光谱表征分析表明,碳和钇的掺杂都拓展了其吸收光谱到可见光区域,且抑制了光生电子和空穴对的复合,进而提高了材料的光催化活性.碳和钇共掺杂的混相TiO_2具有较高可见光光催化活性的主要原因有两个方面:一是元素掺杂减小了TiO_2的带隙使得材料具有可见光响应;二是金属和非金属元素在锐钛矿相与金红石相TiO_2中不同的掺杂特性形成的协同效应,抑制了光生电子和空穴的复合.
Because of its low toxicity, high stability and low preparation cost, TiO_2 has been widely used, especially as a photocatalyst in the degradation of environmental pollutants has been widely concerned; however, pure TiO 2 Larger photo-carrier recombination rate and wider Of the bandgap limits its application.As a widen method of photocatalytic light absorption, elemental doping is widely used in the modification and modification of various photocatalysts, while the coexistence of two photocatalytic TiO 2 phases can effectively inhibit the photogeneration Carrier recombination.Therefore, it is feasible to take proper method to make effective use of these two TiO 2 modification methods to obtain a more practical potential photocatalyst.In this paper, a simple sol-gel process is used to synthesize anatase Phase mixed with rutile phase co-doped with carbon and yttrium to obtain a higher activity of visible light response photocatalysts.X-ray powder diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscopy and other means of characterization The effect of carbon and yttrium doping on the structure of TiO 2, we found that carbon doping is conducive to the formation of rutile and the material has a larger grain size, yttrium doping has Which is conducive to the formation of anatase phase and can refine the grain size of the material and increase the specific surface area of the material, resulting in better photocatalytic activity of the material. Photocatalytic Degradation of Methylene Blue (MB) in a 30 W Fluorescent Lamp The results show that the CY-TiO 2 samples have higher photocatalytic activity than single-doped and undoped samples, and the order is CY-TiO 2> Y-TiO 2> C-TiO 2> TiO 2 ≈P25. In addition, the kinetics of degradation reaction The results showed that the photodegradation rate of MB in CY-TiO_2 sample was 3.5 times that of undoped sample under the same conditions.The results of the study on the structure and photocatalytic degradation of MB in different yttrium-doped samples showed that yttrium doping promoted anatase The formation of TiO_2 shows that TiO_2 can be doped into the anatase phase only with proper doping of yttrium to optimize the photocatalytic properties of mixed phase TiO_2.The photodegradation of MB at different heat treatment temperatures The properties also indicate that a certain heat treatment temperature favors the composition of the appropriate anatase phase and rutile phase and thus favors the synergistic effect of the phases.Ultraviolet-visible spectroscopy and fluorescence spectroscopy characterization indicate that the doping of both carbon and yttrium Exhibited its absorption spectrum in the visible region, and inhibited the recombination of photogenerated electron and hole pairs, thereby increasing the photocatalytic activity of the material.The main reason for the higher visible light photocatalytic activity of co-doped carbon and yttrium There are two aspects: one is the doping of element reduces the bandgap of TiO 2 and makes the material have visible light response; the other is the synergistic effect of different doping characteristics of metal and nonmetal elements in anatase phase and rutile phase TiO 2, The photogenerated electron and hole compound.