N掺杂纳米TiO_2的制备及光催化性能研究

以盐酸羟胺为N源,按r(盐酸羟胺:钛酸四丁酯)分别为1:2,1:1,3:2,2:1和3:1掺杂,采用sol-gel法一步制备N掺杂纳米TiO2。研究了焙烧温度和N掺杂量对样品晶相结构及其在紫外光和紫外–可见光下对罗丹明B光催化活性的影响。结果表明,增大N掺杂量可抑制样品由锐钛矿相向金红石相转变。r(盐酸羟胺:钛酸四丁酯)为2:1时,样品经500℃焙烧后对罗丹明B的紫外光催化降解率1h内达54.81%,样品经600℃焙烧后对罗丹明B的紫外–可见光催化降解率2h内可达99.13%。     

N 和 Fe 共掺杂对TiO2电子结构和光学性质影响的第一性原理研究

本文采用基于密度泛函理论的第一性原理研究了N 和 Fe共掺杂锐钛矿相TiO2的电子结构和光学特性。计算结果表明,不同位置N 和 Fe共掺杂影响共掺TiO2的稳定性。通过态密度讨论了掺杂TiO2带隙变窄的机理。 不同位置N 和 Fe共掺杂影响了可见光吸收。N 和 Fe共掺杂的协同效应导致了可见光吸收的增强。因此,N 和 Fe共掺杂也许增强TiO2在可见光区的光催化能力。     

锐钛矿TiO_2的水热法制备以及紫外光降解甲醛

用硫酸钛水热法制备了纳米TiO2光催化剂,研究了纳米TiO2的形态结构特征及其光催化性能,并探讨了甲醛溶液的初始pH值和初始浓度、TiO2用量、降解温度和时间对光催化降解反应的影响。结果表明,制备的锐钛矿TiO2产物平整而密实,它由八面体结构的TiO2纳米晶大面积自组装而成。在35℃降解温度下采用254nm紫外光源照射1h后,锐钛矿TiO2对甲醛的降解率达到51.10%,2h后达68.42%。     

掺Fe~(3+)的A-TiO_2的水热法制备及其可见光光催化性能

以硫酸钛为原料,用水热法制备了掺Fe3+的TiO2粉末,并对其晶相结构进行了分析,考察了自制掺Fe3+的TiO2对甲基蓝溶液的光催化性能。结果表明:所制备的TiO2为锐钛矿型TiO2(A-TiO2)。可见光照下,用自制掺Fe3+的A-TiO2降解甲基蓝溶液的最佳条件是:于ρ(甲基蓝)为8mg/L的溶液中加入0.0203g掺Fe3+为5%(摩尔分数)的A-TiO2粉末,并加入φ(H2O2)为4%,室温反应4h,最高降解率达到约88%。     

铁、镧共掺杂纳米TiO2可见光催化性能研究

通过溶胶-凝胶(Sol-Gel)法制备了铁、镧共掺杂纳米TiO2,采用X线衍射仪(XRD)、X线光电子能谱(XPS)、紫外-可见分光光度计(UV-Vis)和荧光分光光度计(FL)等测试手段对样品进行表征。结果表明,500℃煅烧后的掺杂TiO2均呈锐钛矿型,平均粒径为6.1nm,掺杂抑制了TiO2粒径的长大,掺杂的Fe3+、La3+能有效进入TiO2晶格。掺杂使TiO2的吸收带边红移且在可见光区的光吸收增强,样品的荧光强度越小,催化效果越好。可见光光催化降解甲基橙实验结果表明,可见光照射5h,最佳共掺杂的0.01%Fe/0.6%La-TiO2对甲基橙的降解率达40.7%。     

Ag掺杂TiO2纳米晶粉体的制备及性能表征

以钛酸丁酯、无水乙醇、硝酸银等为原料,通过溶胶-凝胶法制备了不同Ag掺杂含量的TiO2纳米晶粉体,用X射线衍射（XRD）、扫描电子显微镜（SEM）和透射电子显微镜（TEM）检测分析了粉体的晶型转化、微观形貌和晶粒尺寸,用光致发光光谱（PL）表征材料的光电性能。结果表明,Ag掺杂后的TiO2纳米晶粉体的锐钛矿相比未掺杂Ag样品的含量有所增多,当Ag掺杂量为1%和3%时,锐钛矿的相对含量约为65%;随着Ag掺杂量的增加,锐钛矿晶粒尺寸逐渐减小;由TEM图像可知,Ag颗粒较为均匀地弥散在TiO2纳米晶粉体中;由PL荧光检测结果可知,Ag掺杂TiO2纳米晶粉体的荧光强度比未掺杂的TiO2纳米晶粉体的低。试验结果表明,Ag颗粒较为均匀地弥散在TiO2纳米晶粉体中,有利于在锐钛矿界（表）面形成Ti-O-Ag的键合,有效阻止锐钛矿向金红石的转变,同时抑制锐钛矿TiO2纳米晶粒的增长,Ag颗粒与TiO2纳米晶粉体接触形成肖特基势垒,加速光生电子由TiO2向Ag颗粒传输,减小光生电子与空穴的复合几率,从而提高TiO2纳米晶粉体的光电性能。     

Ag/S/C共掺杂纳米TiO2的制备与光催化活性

采用溶胶-凝胶法制备了Ag/S/C共掺杂纳米TiO2,用于光催化降解气相乙醛.XRD分析结果表明掺杂纳米TiO2均为锐钛型晶相,BET测试表明它们具有较高的比表面积.UV-vis吸收表明S和C掺杂能明显降低TiO2的能隙宽度,而Ag 对此作用较小.Ag 掺杂能促进光生电子-空穴对的分离,从而提高光催化活性.Ag-S-C-TiO2-1催化剂的催化活性高于其它样品,在焙烧温度500℃,Ti∶Ag 摩尔比100∶1,Ti∶SCN-摩尔比1∶4时催化活性最强.Ag/S/C掺杂TiO2光催化活性除受前驱体影响外,还由于其晶相为锐钛型,并且比表面积高,能隙宽度低,因此有良好的光催化活性.     

Fe~(3+)掺杂TiO_2纳米晶溶胶的制备及性能

采用sol-gel法制备了Fe3+掺杂锐钛矿型TiO2纳米晶溶胶。对溶胶的物相结构和粒度分布进行了分析,并考察了薄膜的UV-Vis吸收光谱及溶胶的光催化性能。结果表明:Fe3+掺杂可提供杂质能级抑制电子与空穴的复合,且对TiO2溶胶粒子具有细化作用,因此TiO2溶胶的光催化活性提高,比未掺杂时最大提高了近30%。但Fe3+掺杂过多可能成为电子与空穴复合的中心,导致TiO2溶胶的光催化活性降低。r(Fe:Ti)的最佳范围为0.25~0.50。     

Bi_2O_3/TiO_2纳米复合物的微波合成及光催化性质

以硝酸铋和硫酸钛为原料,通过直接投料微波辐射水解合成法制备了掺铋TiO2纳米复合物,并用XRD、TEM进行了表征。结果表明,直接投料摩尔比为1∶10掺铋TiO2纳米复合物,经500℃热处理后晶型为锐钛矿型,粒径为6～10nm。以催化降解甲基橙来考察其光催化活性,结果表明所制备的纳米复合物是一个好的催化剂。研究了Bi3+的掺杂量、热处理温度、催化剂用量对掺铋TiO2纳米复合物光催化性能的影响。当催化剂用量为1g/L时,2mg/L的甲基橙溶液在紫外光辐射30min后,降解率达到97%。该复合物对甲基橙溶液的光催化降解符合一级动力学方程。     

锌掺杂纳米TiO2光催化剂制备条件研究

采用sol-gel法制备Zn2+掺杂纳米TiO2光催化剂,以气态甲苯为模型污染物,考察了掺杂前驱体、掺杂浓度、焙烧温度及焙烧时间等制备条件对Zn2+-TiO2光催化性能的影响,并通过XRD对其结构进行了表征。结果表明:Zn2+掺杂显著提高了TiO2光催化活性;Zn2+-TiO2的最佳制备条件为硝酸锌为掺杂前驱体r,(Zn:Ti)为0.01,焙烧温度500℃、焙烧时间3.5 h。     

钕掺杂纳米二氧化钛光催化活性研究

采用溶胶-凝胶法在Si(111)衬底上制备纳米TiO2薄膜,利用电化学阴极还原法对TiO2纳米薄膜掺杂Nd3+,对其结构及光催化活性进行研究,结果显示,所制备的样品均为多晶结构,随着Nd3+掺杂量的增加颗粒尺寸明显减小,比表面积增大.Nd3+的掺杂导致TiO2光催化剂吸光能力增强,同时吸收限红移,提高了光的利用率,并且当掺杂量为1.2%时,光催化活性最好.     

Ag/TiO2/WO3 nanoparticles with efficient visible light photocatalytic activity

A simple strategy for synthesizing Ag decorated TiO2/WO3 composite nanoparticles by sol-gel method used as recyclable photocatalyst is introduced. The photocatalytic efficiency to the degradation of methyl blue (MB) by Ag/TiO2/WO3 nanoparticles is studied under ultraviolet-visible (UV-Vis) light irradiation. It shows that the photocatalytic efficiency of Ag/TiO2/WO3 photocatalyst achieves 96% in 20 min, which is 16 times higher than that of pristine TiO2 at the same conditions. The Ag/TiO2/WO3 photocatalyst can still reach the degradation rate of 90% in the fifth degradation experiment, indicating a good stability and photocatalytic activity.     

锐钛型掺铁TiO_2可见光催化降解苯胺的研究

为了研究掺铁TiO2对苯胺的光催化降解效果,以硫酸钛为原料采用水热法制备了锐钛型掺铁TiO2粉末,确定了它在可见光照射下对苯胺溶液的催化降解工艺条件。结果表明,在如下最佳条件下:苯胺初始质量浓度(0)为50 mg/L,溶液pH=7,掺铁0.2%(摩尔分数)的锐钛型TiO2的质量浓度为1.0 g/L,室温(17℃)下可见光照射反应1 h,苯胺的降解率达到71.46%。     

掺Pb的TiO2纳米功能材料的制备及其光催化性能

采用溶胶－凝胶法制备了掺Pb的摩尔比分别为0.5%、1%、3%、5%、7%、10%的改性TiO2纳米粒子，并利用XRD和UV－VIS检测技术对所制得的样品进行了表征，考察了焙烧温度和掺Pb量对材料组成、结构和光学性质的影响；另外，以模拟太阳光下苯酚的光催化降解为模型反应，对Pb改性的TiO2纳米粒子的光催化活性进行了评价，考察了掺Pb量对材料催化性能的影响。结果表明，掺入适量的Pb后，TiO2纳米粒子的光催化活 性得到较大的提高，这可能是由于Pb进入TiO2晶格中生长成了新相PbxTi1-xO2，从而使材料的光响应范围向可见光区移动，提高了对可见光的利用率。本实验表明，掺Pb的摩尔比为3％的改性TiO2纳米粒子的光催化活性最高。     

GaN纳米线的制备及光催化性能研究

采用化学气相沉积法(CVD)制备了大量的GaN纳米线,使用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、X射线能谱(EDS)和光致发光光谱仪(PL)对制备的样品形貌、结构、成分和发光性能进行了表征,并对其进行降解罗丹明B水溶液的光催化性能测试。结果表明,通过化学气相沉积法制备出了高质量的GaN纳米线,且GaN作为催化剂有一定的光催化效果。罗丹明B水溶液会因染料自身敏化作用而降解,但实验发现达到相同降解水平时无催化剂要比有催化剂至少多10 min。GaN作为催化剂时的降解速率k值为0.068 min-1,其数值相对于无催化剂时提高了17.2%。     

UV/visible-light photodegradation of organic dyes over mesoporous titania prepared by using 2,4,5-triphenylimidazole as template

In this work, mesoporous TiO₂ compose of anatase and brookite phases (M-TiO₂) has been synthesized using 2,4,5-triphenylimidazole as template. The physical features of the as-prepared catalyst was measured by X-ray diffraction (XRD), low-temperature nitrogen adsorption/desorption, UV–visible diffuse reflectance spectrum, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The photocatalytic performance of the catalyst was evaluated in terms of the degradation of organic dyes. It is found that M-TiO₂ exhibits reasonable activity under UV light and can significantly degrade methylthionine chloride, rhodamine B, gentian violet, safranine T, methyl violet and fuchsine basic under visible-light irradiation (λ≥420 nm).     

Solvothermal synthesis and photocatalytic properties of CdS nanowires under UV and visible irradiation

CdS nanowires (NWs) were synthesized by the solvothermal method. The synthesis yields NWs with hexagonal phase structure. The phase, vibration modes, morphologies and optical properties of CdS NWs were investigated by X-ray powder diffraction (XRD), Raman spectrophotometry, scanning and transmission electron microscopy (SEM and TEM) and UV–visible spectroscopy, respectively. The results show that the as-synthesized product is hexagonal CdS NWs with the diameter of 20–30 nm and length of up to 5 μm. Photocatalytic degradation of methyl orange (MO) and rhodamine B (RhB) was investigated. It was found that CdS NWs possess excellent catalytic degradation activity owing to their effective absorption over the visible range. The highly photocatalytic activity suggested possible application in the treatment of organic pollutants under visible light irradiation.     

Enhanced photo-induced charge separation and solar-driven photocatalytic activity of g-C3N4 decorated by SO42−

SO₄²⁻ decorated g-C₃N₄ with enhanced photocatalytic performance was prepared by a facile pore impregnating method using (NH₄)₂S₂O₈ solution. The photocatalysts were characterized by the Brunauer–Emmett–Teller (BET) method, X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–vis diffuse reflectance spectroscopy (DRS), transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS) and surface photovoltage (SPV) spectroscopy, respectively. The separation efficiency of photo-generated charge was investigated using benzoquinone as scavenger. The results demonstrate that sulfating of g-C₃N₄ increases the adsorption of rhodamine B on g-C₃N₄, the hydroxyl content and the separation efficiency of photo-generated charge. The photocatalytic activity of SO₄²⁻/g-C₃N₄ for decolorization of rhodamine B and methyl orange (MO) aqueous solution was evaluated. The result shows that loading of 6.0 wt% SO₄²⁻ results in the best photocatalytic activity under simulated solar irradiation and SO₄²⁻ play an important role in boosting the photocatalytic activity.