TiO2/活性炭负载型光催化剂的溶胶-凝胶法合成及表征

以钛酸四丁酯为钛源,采用溶胶-凝胶法在多孔活性炭(AC)表面合成TiO2前驱体,在氮气保护下程序升温处理制得TiO2/AC负载型光催化剂.采用X射线衍射、漫反射光谱、傅里叶变换红外光谱、扫描电镜、能量色散谱和低温液氮吸附等对光催化剂晶相结构、光谱特征及表面结构进行了表征.结果表明,AC可提高TiO2分散性能,降低TiO2团聚体的尺寸,并抑制其由锐钛矿相向金红石相的转变.TiO2与AC接触界面处有Ti-O-C键生成.另外,AC的含量对TiO2的能阈结构和晶粒大小影响不大.苯酚溶液的光催化降解测试结果表明,AC负载可为TiO2提供高浓度反应环境,适宜量的负载可显著提高TiO2对有机稀溶液的光催化降解活性.对于50mg/L苯酚的光催化降解,AC的质量分数分别为5%,9%和11%时催化剂协同系数分别为1.1,1.5和1.3.循环使用7次后,AC含量为9%的催化剂对苯酚的降解率仍达95.84%.     

Photocatalytic Hydrogen Production by the Sensitization of Sn(IV)-Porphyrin Embedded in a Nafion Matrix Coated on TiO2

Efficient utilization of visible light for photocatalytic hydrogen production is one of the most important issues to address. This report describes a facile approach to immobilize visible-light sensitizers on TiO₂ surfaces. To effectively utilize the sensitization of Sn(IV) porphyrin species for photocatalytic hydrogen production, perfluorosulfonate polymer (Nafion) matrix coated-TiO₂ was fabricated. Nafion coated-TiO₂ readily adsorbed trans-diaqua[meso-tetrakis(4-pyridinium)porphyrinato]tin(IV) cation [(TPy^HP)Sn(OH₂)₂]⁶⁺ via an ion-exchange process. The uptake of [(TPy^HP)Sn(OH₂)₂]⁶⁺ in an aqueous solution completed within 30 min, as determined by UV-vis spectroscopy. The existence of Sn(IV) porphyrin species embedded in the Nafion matrix coated on TiO₂ was confirmed by zeta potential measurements, UV-vis absorption spectroscopy, TEM combined with energy dispersive X-ray spectroscopy, and thermogravimetric analysis. Sn(IV)-porphyrin cationic species embedded in the Nafion matrix were successfully used as visible-light sensitizer for photochemical hydrogen generation. This photocatalytic system performed 45% better than the uncoated TiO₂ system. In addition, the performance at pH 7 was superior to that at pH 3 or 9. This work revealed that Nafion matrix coated-TiO₂ can efficiently produce hydrogen with a consistent performance by utilizing a freshly supplied cationic Sn(IV)-porphyrin sensitizer in a neutral solution.     

基于晶体学原理的高效光催化材料的设计与制备

光催化技术是一种将太阳能转换为化学能的新技术,基于该技术可利用半导体光催化材料实现光催化分解水制氢、二氧化碳还原制备有机物、降解有机污染物等,是解决未来能源和环境问题的潜在途径之一.然而,作为光催化技术的核心,光催化材料面临着光吸收范围窄、光生载流子分离效率低等问题,这些问题严重制约着光催化能量转化效率及其实际应用.针...     

凹凸棒黏土-SnO2-TiO2复合材料的制备及其光催化性能

以凹凸棒黏土为基体,通过原位溶胶-凝胶包覆工艺,将SnO2-TiO2复合氧化物负载于凹凸棒黏土表面制备凹凸棒黏土复合光催化剂(Att-SnO2-TiO2)。采用XRD、BET、TEM等分析测试技术对产物进行了表征。结果表明,SnO2-TiO2复合氧化物均匀地负载于凹凸棒黏土表面,其平均粒径约为10 nm;经过复合氧化物负载改性后,凹凸棒黏土的表面形貌得到明显改善,产物的包覆效果好、比表面大。以光催化降解甲基橙为探针,研究了凹凸棒黏土复合光催化剂的光催化性能。结果表明,凹凸棒黏土复合光催化剂显示出优异的光催化性能,其光催化活性顺序为Att-SnO2-TiO2>Att-SnO2>Att-TiO2。以性能最佳的Att-SnO2-TiO2为催化剂光降解甲基橙30min后,甲基橙的降解率达99%。实验表明,Att-SnO2-TiO2复合光催化剂可重复利用。     

亚硝酸盐的光催化氧化

利用半导体光催化剂Bi₂O₃对含亚硝酸盐废水的处理进行了研究,并讨论了影响亚硝酸盐氧化率的主要因素.实验结果表明:选择活性较高的Bi₂O₃作为光催化剂,当其用量为0.050 g,试液pH＝3.70,NO₂^--N起始浓度为 400.0 mg/L,光照1 h时,亚硝酸盐的氧化率达到7.0%.     

新型复合电极与偶氮染料分子的氧化降解反应的研究

介绍了具有合成H_2O_2和光催化性能的双功能型复合电极、双功能复合电极是 将TiO_2/C光催化剂负载在具有合成H_2O_2性能的新型载体上形成的。在光反应器 中,复合电极作阴极,钌-钛不溶性电极作阳极,低压汞灯作光源,实现了光化学 氧化与光催化氧化在同一电极/溶液界面上的联合作用。当反应器工作时,复合电 极中的TiO_2/C光催化层表面进行着光催化反应,在载体的三相界面上进行着O_2的 2电子H_2O_2的电化学反应,电流效率达82%（J = 15 mA/cm~2）,为·OH自由基的 生成提供了物质源,而且氧的2电子还原反应电位使其表面的TiO_2获得相对于平带 电位约+0.5 V的阳极偏压,改善了TiO_2的光催化活性。实验结果表明,复合电极 对提高偶氮染料分子活性艳红（K-2BP）的氧化降解速度起了重要作用。实验发现 偶氮染料分子在复合电极表面的吸附量与反应速度密切相关。文中讨论了复合电极 的作用原理及偶氮染料分子的氧化降解过程。     

纳米SnO2@TiO2包覆催化剂的制备及表征

采用活性层包覆法在自制细SnO2胶体粒子表面包覆TiO2,制备出SnO2@TiO2包覆型复合催化剂,以其对有机磷农药DDVP的降解效果作为评价光催化活性的标准,对制备条件进行了优化,并用XRD、TEM和BET等手段对样品进行了表征,结果表明,SnO2胶体乙醇溶液含水量20％,钛酸丁酯质量分数为34.5％。灼烧温度680℃时制得TiO2含量56.45％的包覆样品SnO2@TiO2为纳米级粒子,且其光催化活性最佳。     

SO4^2—／TiO2固体酸催化剂的酸强度及光催化性能

SO4^2-/TiO2固体酸可用于光催化降解溴代甲烷,其光催化性能明显优于TiO2光催化剂,晨相同反应条件下,SO4^2-/TiO2的光催化活性比TiO2提高2－10倍,当H2S4浸渍液浓度为1mol/L时,制得的SO4^2-/TiO2酸性最强（H0＜－12.14）,具有超强酸性和最高的光催化活性。     

Preparation of Ag3PO4/TiO2(B) Heterojunction Nanobelt with Extended Light Response and Enhanced Photocatalytic Performance

Photocatalytic degradation, as an emerging method to control environmental pollution, is considered one of the most promising environmental purification technologies. As Tibet is a region with some of the strongest solar radiation in China and even in the world, it is extremely rich in solar energy resources, which is ideal for applying photocatalytic technology to its ecological environment protection and governance. In this study, Na₂Ti₃O₇ nanobelts were prepared via a hydrothermal method and converted to TiO₂∙xH₂O ion exchange, which was followed by high-temperature calcination to prepare TiO₂(B) nanobelts (“B” in TiO₂(B) means “Bronze phase”). A simple in situ method was used to generate Ag₃PO₄ particles on the surface of the TiO₂ nanobelts to construct a Ag₃PO₄/TiO₂(B) heterojunction composite photocatalyst. By generating Ag₃PO₄ nanoparticles on the surface of the TiO₂(B) nanobelts to construct heterojunctions, the light absorption range of the photocatalyst was successfully extended from UV (ultraviolet) to the visible region. Furthermore, the recombination of photogenerated electron–hole pairs in the catalyst was inhibited by the construction of the heterojunctions, thus greatly enhancing its light quantum efficiency. Therefore, the prepared Ag₃PO₄/TiO₂(B) heterojunction composite photocatalyst greatly outperformed the TiO₂(B) nanobelt in terms of photocatalytic degradation.     

Effect of Binder on the Structure and Properties of Silicon Powder-supported TiO2 Photocatalysis Material

Recoverable TiO2 photocatalysis material supported by silicon powder was prepared with sol-gel method, afterwards the silica gol and sodium silicate were used as molding binder respectively to investigate their effects （including binder type and binder addition quantity） on the crystal structure and catalysis properties of photocatalyst. In this work, the catalysis activity was defined as the degradation rate of methyl orange solution upon ultraviolet lamp irradiation, and the specific areas were determined with nitrogen desorption method. TiO2 crystal form was measured with X-ray powder diffraction and their micro-morphology was observed with SEM. Experimental results indicate that these two binders do not affect the crystal form transformation of TiO2, but silica gol can increase the specific surface area of TiO2 photocatalyst obviously and the addition of sodium silicate can decrease it. In all, silica gol is a better candidate than sodium silicate for higher catalysis property. In conclusion, 6% silica gol is the optimal addition concentration. Under this condition, the ratio of anatase to rutile TiO2 is 64：36, the specific area is 29.67 m^2/g, and as expected, the degradation rate of methyl orange could be as high as 90% after irradiation for 5 days.