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1.
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
2.
In an attempt to identify the fundamental processes that influence ion transport through metallic surface layers, we have studied the transmission of O + ions through discontinuous Au films adsorbed on TiO 2(110). A low energy (< 10 eV) O + ion beam is generated via electron stimulated desorption when an Au-dosed TiO 2(110) substrate is bombarded with a focused 250 eV electron beam. Low energy ion scattering data indicate that Au evaporated under ultrahigh vacuum conditions at 300 K forms three-dimensional clusters on TiO 2(110). As the Au coverage increases, the formation of Au clusters on TiO 2(110) blocks a fraction of the TiO 2 surface and the O + yield is attenuated. However, for high coverages (≥30% Au covered substrate) the O + signal decreases at a faster rate than the TiO 2 open area fraction. We attribute the attenuation of the O + yield for high Au coverages mainly to blocking of O + by Au clusters, to deflection of trajectories by the image force between ions and Au clusters, and to charge transfer between desorbing O + and neighboring Au clusters. 相似文献
3.
用溶胶-水热法制备了Sm3+掺杂的Ti O2粉体(Ti O2∶Sm3+),将其按不同质量分数掺杂到P25基体中,制备了具有下转换功能的光阳极,并将其用于染料敏化太阳能电池中,提高了电池的光电性能。荧光光谱显示,Ti O2∶Sm3+粉体可以将紫外光转换为570~700 nm的可见光。当下转换光阳极中Ti O2∶Sm3+粉体的掺杂质量分数为80%时,短路电流密度达到13.12 m A/cm2,与纯P25光阳极相比,提高了26.5%,转换效率也提高了23.5%。 相似文献
4.
为了研究锌卟啉/TiO 2复合光催化剂的光催化效率及电子转移问题, 本文采用溶胶凝胶法制备了锌卟啉/TiO 2的混合光催化材料, 并利用紫外可见光谱、电子顺磁共振谱对锌卟啉/TiO 2复合光催化剂进行了表征与分析. 采用溶胶凝胶法制备了锌卟啉-TiO 2的混合光催化材料, 通过比较纯P25型TiO 2和掺入质量比分别为0.2%, 0.5%, 0.9%锌卟啉敏化剂的锌卟啉/TiO 2混合光催化材料的紫外可见光谱图可知, 加入适量锌卟啉敏化剂可提高TiO 2对甲基橙溶液的降解效率, 过多的掺入锌卟啉敏化剂会导致TiO 2表面被敏化剂覆盖, 从而影响了其对光子的吸收, 降低TiO 2的光催化效率, 降低TiO 2的光降解率, 甚至低于纯TiO 2的光降解率. 应用电子顺磁共振技术对锌卟啉敏化TiO 2光催化剂的光催化机理进行了合理的解释, 当使用紫外可见光源对粉末样品进行辐照时, 锌卟啉受光辐照产生的激发态电子促进具有强氧化性的Ti 3+和超氧根自由基的生成, 从而有效的促进了光生空穴-电子对的分离, 提高了TiO 2的光催化性能. 相似文献
5.
In this paper, green and red up-conversion emissions of Er 3+–Yb 3+ co-doped TiO 2 nanocrystals were reported. The phase structure, particle size and optical properties of Er 3+–Yb 3+ co-doped TiO 2 nanocrystals samples were characterized by using X-ray diffraction (XRD), transmission electron microscopy (TEM), UV–vis–NIR absorption spectra and photoluminescence (PL) spectra. Green and red up-conversion emissions in the range of 520–570 nm ( 2H 11/2, 4S 3/2→ 4I 15/2) and 640–690 nm ( 4F 9/2→ 4I 15/2) were observed for the Er 3+–Yb 3+ co-doped TiO 2 nanocrystals. The visible up-conversion mechanism and temperature dependence of up-conversion emission for Er 3+ in TiO 2 nanocrystals were discussed in detail. 相似文献
6.
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
7.
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
8.
为了提高壳聚糖的水溶性及其止血方面的性能,将壳聚糖(CS)进行羧甲基化改性,并引入具有抗菌作用的Ag +和TiO 2,制备出羧甲基壳聚糖复合止血材料。首先,在壳聚糖中引入羧甲基,制得羧甲基壳聚糖(CMCS),之后向其中引入Ag +和TiO 2,分别制备出Ag +-CMCS、TiO 2-CMCS和Ag +-TiO 2-CMCS复合材料。然后,采用FTIR、XRD、SEM等手段对复合材料的结构进行表征。最后,对复合物的凝血、止血性能进行了测试。实验结果表明:改性后的羧甲基壳聚糖的IR图谱在3 423 cm -1和1 380 cm -1处出现了羧甲基壳聚糖钠盐的特征吸收峰。改性后的羧甲基壳聚糖在XRD图谱中表现出了金属晶态。CMCS的粒径为14.8 nm左右,Ag +粒径为143.5 nm左右,纳米TiO 2的粒径为267.2 nm左右,且三者分散的很均匀。Ag +-TiO 2-CMCS的凝血、止血效果要优于Ag +-CMCS和TiO 2-CMCS,同时Ag +-CMCS和TiO 2-CMCS的凝血、止血效果要优于CMCS。 相似文献
9.
Compositional changes induced by 3.5 keV Ar + sputtering in TiO 2, NiO, NiTiO 3 and a (TiO 2 + NiO) mixture have been quantitatively studied by XPS. Although all the samples show important changes in their stoichiometry, the extent of the decomposition depends on the compound. The stability of Ti 4+ appears to be enhanced by the presence of Nisu2+ cations which, on the other hand, are more easily reduced to Ni 0 than in pure NiO. To explain these results a redox solid state reaction between the intermediate phases formed during sputtering is proposed, which tends to preserve the most stable phases. 相似文献
10.
采用射频磁控溅射法制备得到Er~(3+)/Yb~(3+)TiO_2薄膜,980 nm的抽运源作用下上转换可以得到490 nm的绿光和670 nm的红光,上转换红、绿光发光强度受到烧绿石Er_xYb_(2-x)Ti_2O_7晶体的生成以及Er~(3+)/Yb~(3+)掺杂浓度的影响,实验表明,适量共掺杂Er~(3+)/Yb~(3+)可明显增强上转换发光,Er~(3+)在上转换发光中起主要作用,而引入敏化离子Yb~(3+)可以大大提高上转换发光效率,磁控溅射法制备的TiO_2薄膜声子态密度较小,从而抑制了无辐射跃迁过程,导致490nm绿光形成以及红光强度大于绿光强度。 相似文献
11.
通过水解TiCl 4制备了锐钛矿结构TiO 2纳米粒子, 并用时间分辨荧光光谱研究了5(6)CFL(5(6)-Carboxyfluorescein, 简称5(6)CFL)染料敏化TiO 2纳米粒子体系的光致电子转移动力学. 5(6)CFL染料敏化TiO 2纳米粒子能形成电荷转移复合物, 这归因于染料分子的激发电子态波函数Ψ(D *)与电荷分离态波函数Ψ(D + +e -)之间的耦合作用. 当激发5(6)CFL染料敏化TiO 2纳米粒子体系时, 电子以两种不同方式注入TiO 2纳米粒子导带: 第一, 通过5(6)CFL染料分子的激发态注入; 第二, 从电荷转移复合物(5(6)CFL/TiO 2)直接注入. 时间分辨荧光光谱表明, 在水溶液中纯5(6)CFL染料的荧光以寿命为τ 1=41 ps (74.4%) 和τ 2=3.22 ns (25.6%) 的双e指数衰减, 而5(6)CFL染料敏化TiO 2纳米粒子体系的荧光分别以时间常数为τ 1=44 ps (90.4%), τ 2=478 ps (8.6%) 和τ 3=2.41 ns (1.0%) 的三e指数衰减. 本文的研究工作能够为染料敏化太阳能电池的光致电子转移机理提供有价值的参考. 相似文献
12.
在经典的平面异质结钙钛矿太阳电池中,TiO_2致密层的电子传输性能一直是获得优异光伏性能的决定性因素之一.相较于spriro-OMe TAD等常见的空穴传输材料优异的空穴传输能力,作为电子传输材料的TiO_2的导电性较弱,无法形成良好的电荷匹配.为了解决这个问题,我们使用自组装的十二烷二酸(DDDA)单分子层来修饰TiO_2致密层的表面,TiO_2致密层的导电性能得到大幅提升,并且其能带结构得到优化,促进了电子传输,降低了电子积聚和载流子复合,使得电池的短路电流密度(JSC)从修饰前的20.34 mA·cm~(-2)提升至修饰后的23.28 mA·cm~(-2),进而使得电池在标准测量条件下的光电能量转换效率从14.17%提升至15.92%.同时还发现,通过DDDA修饰TiO_2致密层,所制备的器件的光稳定性显著提升,器件未封装暴露在AM 1.5光强100 mW·cm~(-2)的模拟太阳光下超过720 min,保持初始效率的71%以上且趋于稳定. 相似文献
13.
为提高稀土掺杂TiO 2薄膜的上转换效率,采用溶胶-凝胶法和旋涂镀膜工艺制备了Yb 3+-Er 3+共掺杂SiO 2/TiO 2上转换光致发光薄膜,研究了SiO 2对TiO 2薄膜形貌以及发光性能的影响。利用FE-SEM观察了薄膜的表面形貌,利用分光光度计测试了薄膜在近红外光区域的透射率的变化,并用荧光光谱仪测试了薄膜的上转换发光光谱。结果表明:SiO 2的掺杂导致TiO 2颗粒尺寸显著减小,TiO 2薄膜在近红外的透射率也有所下降。在980 nm红外光激发下,SiO 2/TiO 2薄膜在630~670 nm处获得了明显的上转换红光发射,在516~537 nm和537~570 nm处获得了较弱的上转换绿光发射。由上转换发光强度与激光泵浦功率的关系推知,绿色和红色上转换发光均为双光子吸收发射过程。 相似文献
14.
采用电子束沉积方法,以钛酸锶(SrTiO3)为衬底制备铌(Nb)掺杂TiO2薄膜并研究后续H2气氛退火处理对其薄膜样品光电性能的影响.结果发现H2气氛热退火处理能有效改善Nb掺杂TiO2薄膜的导电率,最佳电阻率达到5.46×10-3Ω·cm,在可见光范围内的透光率为60%—80%.导电性能的改善与H2气氛退火处理后多晶薄膜的晶粒尺寸变大和大量的氧空位形成及H原子掺杂有关. 相似文献
15.
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
16.
The phosphated mesoporous TiO 2 (PMT) were synthesized by using evaporation-induced self-assembly approach (EISA) with phosphorus content from 1 to 15 mol%. The X-ray diffraction and N 2 adsorption–desorption isothermal results reveal that the incorporating of phosphorus is of benefit to improving the thermal stability and enhancing the surface area of mesoporous TiO 2 by constraining the growth of anatase crystallite. XPS confirms the phosphorus in the calcined PMT exists as amorphous titanium phosphate in a pentavalent-oxidation state (P 5+) and embedded into the nanocrystalline anatase TiO 2. In photodegradation gas phase acetaldehyde, the photocatalytic activity of PMT samples is higher than that of pure mesoporous TiO 2 and P25. It is believed that the enhancing photocatalytic activity of phosphated mesoporous TiO 2 is mainly caused by two factors relative with the incorporating of phosphorus in framework. 相似文献
17.
Single crystals of Yb 2+-doped LiCaAlF 6 were grown by the Czochralski technique under CF 4 atmosphere. Photoluminescence, thermally stimulated luminescence and decay kinetics of Yb 2+ centre in the LiCaAlF 6 host were measured in the 4–300 K temperature interval. Phenomenological two excited-state-level model is introduced to obtain quantitative characteristics of the excited state dynamics of Yb 2+. The role of Yb 2+ centre in trapping processes is discussed. Moreover, defect centres related to LiCaAlF 6 host were found. 相似文献
18.
采用高温固相法合成Ca 0.8Zn 0.2TiO 3:0.2% Pr 3+,Si 4+和Ca 0.8Zn 0.2TiO 3:0.2% Pr 3+,Si 4+,Lu 3+荧光粉。通过X射线衍射仪、电子顺磁共振光谱仪、显微拉曼光谱仪和荧光光谱仪等表征了该系列荧光粉的物相组成、微观结构和发光性质。结果表明,以β-Si 3N 4为硅源制备的荧光粉具有最佳的光学性能。加入ZnO后,荧光粉由CaTiO 3、Zn 2TiO 4和Ca 2Zn 4Ti 16O 38三相组成,其中CaTiO 3为主相。电子顺磁共振谱证实了Pr 4+存在,Lu 3+的添加使[Pr 4+Ti 3+O 3] +簇显著增加,电子顺磁共振谱和拉曼光谱均证实Si 4+、Lu 3+的掺杂使局部TiO 6簇对称性提高,有利于Pr 3+发光中心的能量传递。在336 nm激发下,荧光粉展示了很强的位于612 nm的红光发射(归属于Pr 3+的 1D 2→ 3H 4跃迁)及理想的红光色坐标(x=0.670,y=0.330)。Si 4+和Lu 3+的添加显著增强了370 nm激发下红光发射,Ca 0.8Zn 0.2TiO 3:0.2% Pr 3+,3.2% Si 4+荧光粉的余辉寿命最长。 相似文献
19.
Interactions of HCOOH with stoichiometric (nearly defect-free) and defective TiO 2(110) surfaces have been studied experimentally using X-ray photoelectron spectroscopy (XPS), ultraviolet photoemission spectroscopy (UPS), and theoretically using electronic structure calculations. The HCOOH saturation coverages were 0.58 ML, 0.77 ML, and 0.92 ML (1 ML ≈ 5.2 × 10 14 cm −2) for nearly defect-free surfaces, for electron-beam exposed surfaces, and for Ar + ion bombarded surfaces, respectively. The excess formic acid adsorption quantitatively corresponds to the number of newly exposed sites created by electron-beam exposure. Electronic structure calculations show a strong adsorptive interaction for formate on cation sites on both stoichiometric and defective TiO 2 surfaces, consistent with the experimental observations. In spite of adsorption at defect sites, little or no defect healing (defect healing means a reduction in defect signal observed by the photoemission measurements) was observed for either electron-beam exposed or Ar + bombarded surfaces by HCOOH exposure up to 10 4L at room temperature. However, some healing will occur if extra energy provided by electrons is introduced to breakdown formate species. In contrast to water adsorption, electronic structure calculations on defective TiO 2 have found that formate is located in an asymmetric position with respect to the Ti 3+ sites with a potential additional interaction with the Ti 4+ site. 相似文献
20.
采用匀胶法制备了厚度在微米量级的 Si/[TiO 2/Al 2O 3] 2TiO 2和Si/[TiO 2/MgO] 2/TiO 2 多层介质膜反射镜. 采用太赫兹(THz)时域透射光谱系统获得了多层膜的时域透射谱. 用传输矩阵法模拟了Si/[TiO 2/Al 2O 3] 2TiO 2 和Si/[TiO 2/MgO] 2/TiO 2两种分布式布拉格反射镜 (DBR)的反射相移和相位穿透深度等光学特性. 设计了两种结构为 DBR/LT-GaAs/DBR的对称THz光学微腔结构并模拟了腔结构的辐射光谱. 结果表明:通过引入谐振腔, 两种DBR组成的微腔器件在谐振波长处的强度分别提高了19和14倍. 其中Si/[TiO 2/Al 2O 3] 2TiO 2/LT-GaAs (12 μm)/ [TiO 2/Al 2O 3] 2TiO 2腔的辐射光谱存在两个峰, 分别位于208和248 μm, 并分析了出现两个谐振峰的原因. 探讨了通过引入介质谐振腔实现对THz源的辐射特性进行调控的可行性.
关键词:
分布式布拉格反射镜
光子晶体
穿透深度
太赫兹微腔 相似文献
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