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1.
基于密度泛函理论的第一性原理平面波超软赝势法, 采用局域自旋密度近似加Hubbard U值方法研究了纯锐钛矿型TiO 2, N, Cu单掺杂TiO 2及N/Cu共掺杂TiO 2 的晶体结构、电子结构和光学性质. 研究结果表明, 掺杂后晶格发生相应畸变, 晶格常数变大. N 和Cu的掺杂在TiO 2禁带中引入杂质能级, 禁带宽度发生相应改变. 对于N掺杂TiO 2禁带宽度减小较弱, 而Cu掺杂和N/Cu共掺TiO 2禁带宽度显著降低, 导致吸收光谱明显红移, 光学催化性增强, 有利于实际应用. 相似文献
2.
为了研究TiO 2禁带宽度和光吸收系数对其光催化性能的影响,使用Materials Studio的Dmol3和CASTEP模块分别对Ag +、Fe 3+、Pt 4+、La 3+ 4种金属离子掺杂TiO 2的能带结构和光学性质进行分析。分子模拟表明:金属离子掺杂使TiO 2的禁带宽度变窄、吸收波长红移,相同光照条件下光吸收系数增加,影响了TiO 2的光催化性能。光催化反应实验表明:在254 nm照射条件下,TiO 2的禁带宽度为1.09 eV时光催化性能最好,TiO 2的光吸收系数越大,光催化性能越好。 相似文献
3.
采用基于密度泛函理论第一性原理GGA和GGA+U相结合的方法研究了不同掺杂浓度下锐钛矿相和金红石相Nb:TiO2的晶体结构、电子结构以及稳定性.结果表明:锐钛矿相Nb:TiO2能带结构与简并半导体类似,呈类金属导电机理.金红石相Nb:TiO2呈半导体导电机理.Nb原子比Ti原子电离产生出更多的电子.锐钛矿相Nb:TiO2中Nb原子的电离率比金红石相Nb:TiO2的大.以上结果说明锐钛矿相Nb:TiO2比金红石相Nb:TiO2更适宜用作TCO材料;掺杂浓度对其杂质能级,费米能级和有效质量都有影响.Nb原子掺杂浓度越高,材料电离率呈降低趋势;形成能计算结果显示:在富钛条件下不利于Nb原子的掺杂,而在富氧条件下有利于Nb原子的掺杂.对于金红石相和锐钛矿相Nb:TiO2,不论是在贫氧或富氧条件下,随着Nb原子掺杂浓度的提高,形成能均增大. 相似文献
4.
The strong interaction between Pt and TiO 2 under oxidizing atmosphere was studied by means of X-ray photoelectron spectroscopy (XPS) and Ar + sputtering test. The results obtained show that under oxidizing atmosphere Pt 0 atoms can thermally diffuse into TiO 2 lattice and be oxidized to Pt 2+ to substitute for Ti 4+ or form the interstitial ions at 673 K. 相似文献
5.
以钛酸四丁酯、无水乙醇、冰醋酸为原料,在室温下用溶胶-凝胶法制备得到二氧化钛及其掺Fe样品的湿凝胶,室温放置2天后,100 ℃干燥得到干凝胶,在500 ℃下焙烧得到二氧化钛及其掺Fe的粉末状样品. 利用X射线衍射、电子顺磁共振等测试手段对样品进行分析,结果显示所得样品均为锐钛矿,Fe被引入了二氧化钛晶格中,Ti 3+氧化中心信号强度随Fe掺杂量的增加而增强,峰值向磁场减小方向小幅偏移. 在不同测试温度下, 含Fe量为0.1%的Fe-TiO 2样品中Ti 3+氧化中心信号强度随温度升高而增强,峰值也向磁场减小方向小幅偏移. 根据电子顺磁共振理论以及二氧化钛在空气中与O 2的反应解释了这些现象. 相似文献
6.
TiO 2-doped WO 3 thin films were deposited onto fluorine-doped tin oxide coated conducting glass substrates using spray pyrolysis technique at 525 °C. The volume percentage of TiO 2 dopant was varied from 13% to 38%. The thin film samples were transparent, uniform and strongly adherent to the substrates. Electrochromical properties of TiO 2-doped WO 3 thin films were studied with the help of cyclic voltammetry (CV), chronoamperometry (CA) and chronocoulometry (CC) techniques. It has been found that TiO 2 doping in WO 3 enhances its electrochromic performance. Colouration efficiency becomes almost double and samples exhibit increasingly high reversibility with TiO 2 doping concentrations, in the studied range. 相似文献
7.
利用磁控溅射在重掺硼硅(p+-Si)衬底上分别沉积TiO2薄膜和掺硼的TiO2(Ti O2∶B)薄膜,并经过氧气氛下600℃热处理,由此形成相应的TiO2/p+-Si和TiO2∶B/p+-Si异质结。与Ti O2/p+-Si异质结器件相比,TiO2∶B/p+-Si异质结器件的电致发光有明显的增强。分析认为:TiO2∶B薄膜经过热处理后,B原子进入TiO2晶格的间隙位,引入了额外的氧空位,而氧空位是TiO2/p+-Si异质结器件电致发光的发光中心,所以上述由B掺杂引起的氧空位浓度的增加是TiO2∶B/p+-Si异质结器件电致发光增强的原因。 相似文献
8.
S-doped TiO 2 (S-TiO 2) photocatalyst was synthesized by sol–gel method with tetrabutyl titanate and thiourea as precursor. S-TiO 2 was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–vis absorption spectroscopy, transmission electron microscopy (TEM) and the photocatalytic activity was evaluated by 1-naphthol-5-sulfonic acid (L-acid) under UV, visible light and solar light radiation. The results showed that doped S could improve photoabsorption property of TiO 2 in the visible region, leading the increase in the photocatalytical activity of TiO 2. The average particle size of the S-TiO2 photocatalyst is about 10 nm. The S-TiO2-4 photocatalyst contains 100% anatase crystalline phase of TiO2. In the S-TiO2-4 photocatalyst, S does not exist independently, but is incorporated into the crystal lattice of TiO2. In the inner crystal lattice of the S-TiO2-4 photocatalyst, S as S2− replaces O in TiO2, while on the surface of crystal lattice, S exists as S4+ and S6+. The photocatalytical activity of S-TiO2-4 photocatalyst for the photodegradation of L-acid is better than that of pure TiO2. Under the same conditions, the photodegradation efficiency of L-acid for the S-TiO2-4 photocatalyst and the solar light irradiation is 85.1%, while it is only 26.4% for pure TiO2. In addition, the final products of the photocatalysis of L-acid using the S-TiO2-4 photocatalyst are not organic compounds with low molecular weight, but the inorganic compounds. 相似文献
9.
By means of X-ray diffraction, BET nitrogen adsorption, UV-Vis-NIR transmission spectroscopy, transmission electron microscope, scanning electron microscope, X-ray photoelectron spectroscopy and photodegradation of methylene blue, effects of Ag doping on the microstructure and photocatalytic activity of TiO 2 films prepared by sol–gel method were studied. It is found that with a suitable amount (2–4 mol%), the Ag dopant increases the photocatalytic activity of TiO 2 films. The mechanism can be attributed to that (1) anatase grain sizes decrease with Ag doping and the specific surface areas of doped TiO 2 films increase, the charge transfer in TiO 2 films is promoted; (2) by enhancing the electron–hole pairs separation and inhibiting their recombination, the Ag dopant enhances the charge pair separation efficiency for doped TiO 2 films. 相似文献
10.
随着社会经济的发展,环境空气品质已经成为研究热点。TiO 2是一种化学稳定性高,耐腐蚀性强,对人体无毒无害的N型半导体材料。利用TiO 2的光催化性能提高室内环境空气品质已经成为研究焦点,但是由于TiO 2只能在紫外光源下才具有较高的光催化效率,而在可见光源下的光催化效率较低,从而极大的限制了TiO 2在室内环境领域的发展。因此,研发在可见光源下具有良好光催化性能的TiO 2复合材料势在必行。利用元素掺杂改性技术与提高比表面积方法可以改善光催化反应过程中量子效率和对光能的利用率,以加快电子和空穴向表面迁移的速率同时降低光生载流子的复合机率。以二氧化硅SiO 2为模板、聚乙烯吡咯烷酮为成膜剂、硝酸铈Ce(NO 3) 3·6H 2O和硝酸铜Cu(NO 3) 2·3H 2O为改性剂采用溶胶-凝胶法制备均匀粒度分布的Ce-Cu/TiO 2空心微球,并将制备过程分为四个阶段,即纳米SiO 2球模板的制备、Ce-Cu/TiO 2-SiO 2复合微球凝胶的制备、Ce-Cu/TiO 2-SiO 2复合微球的制备和Ce-Cu/TiO 2空心微球的制备。利用傅里叶变换红外光谱仪(FTIR)与X射线衍射仪(XRD)对Ce-Cu/TiO 2空心微球的制备过程各阶段生成物进行测试与分析,即在纳米SiO 2球模板的制备阶段从微观角度研究纳米SiO 2球模板的搭建过程,在Ce-Cu/TiO 2-SiO 2复合微球凝胶的制备阶段研究TiO 2附着于纳米SiO 2球模板的过程,在Ce-Cu/TiO 2-SiO 2复合微球的制备阶段研究煅烧工艺对Ce-Cu/TiO 2-SiO 2复合微球中晶相与结构的影响,在Ce-Cu/TiO 2空心微球的制备阶段研究氢氧化钠溶液对Ce-Cu/TiO 2-SiO 2复合微球中纳米SiO 2球模板洗涤效果的影响。利用紫外-可见分光光度计(UV-Vis)对Ce-Cu/TiO 2空心微球的光响应性能进行测试与分析,以研究Ce-Cu/TiO 2空心微球对可见光源的利用效率。利用激光粒度分析仪(LPSA)与扫描电子显微镜(SEM)对Ce-Cu/TiO 2空心微球的粒度分布与微观形貌进行测试与分析,以研究Ce-Cu/TiO 2空心微球的均匀粒度分布效果。结果表明:以Si-O-Si基团构建非晶体结构的无定形态纳米SiO 2球模板,有利于聚乙烯吡咯烷酮在纳米SiO 2球模板表面附着,从而控制Ce-Cu/TiO 2空心微球的空腔结构。Ce-Cu掺杂基本进入TiO 2晶体,极少进入纳米SiO 2球模板晶体,从而抑制了Ce-Cu/TiO 2-SiO 2复合微球中TiO 2由锐钛矿相向金红石相的转变。Ce-Cu掺杂TiO 2可以促使TiO 2内部形成新的能级,实现能量较小的光子捕获e-和h+,从而提高Ce-Cu/TiO 2空心微球对可见光源的利用效率。Ce-Cu/TiO 2空心微球的表面光滑且不存在明显的缺陷,其形貌呈现良好的球体且粒径分布均匀,即 d90为219.54 nm, d50为151.60 nm、 d10为103.84 nm,以及 d90- d10为115.70 nm。研究结果为进一步获得可见光源下具有良好光催化性能的均匀粒度分布Ce-Cu/TiO 2空心微球提供理论依据和研究基础。 相似文献
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