空气电极/AC作载体对TiO2光催化性能的影响

研究了空气电极和活性碳 (AC)作载体对TiO2 光催化氧化活性艳红 (K 2BP)性能的影响 .实验结果表明 ,用空气电极 /AC作载体能显著提高TiO2 的光催化反应速度 ;空气电极不仅具有良好的合成H2 O2 的性能 ,而且对TiO2 光催化剂可产生大约 +0 .5V的偏压作用 ,大大减小了TiO2 光生电荷的复合几率 ;AC对有机物分子良好的吸附作用提高了有机物分子在TiO2 表面及周围的富集浓度 ,其含量在 2 1%左右可使光催化剂达到最佳的催化效果 .复合电极工作电流密度对活性艳红的氧化脱色速度有影响 ,i=15mA/cm2 ,速度达到最大 ;活性艳红分子在复合电极表面的吸附受溶液pH值的影响 ;提出了复合电极的工作原理 .     

水热预处理合成Bi0.5Y0.5VO4及其光解水性能研究

采用水热反应预处理法制备了Bi0.5Y0.5VO4光催化剂,考察了预处理条件及焙烧温度对光催化活性的影响.利用XRD、SEM、UV-vis和BET等测试手段对样品的晶相组成、表面形貌、光吸收性能和比表面积等物理性质进行了表征.结果表明:预处理后可在温和条件下合成Bi0.5Y0.5VO4(BYV)固溶体,当水热预处理条件为pH=1,焙烧温度为800℃时制备材料活性最高,共负载Pt-Cr2O3助催化剂后具有完全分解水性能,生成氢气和氧气的量分别为80.5μmol/h和43.8μmol/h.     

Electronic properties,quantum capacitance and photocatalyst for water splitting of Sc2CO2 MXene under uniaxial strain

MXenes have wide applications because of the structural flexibility and compositional diversity. Quantum capacitance, electronic and photocatalytic properties of Sc₂CO₂ monolayer under uniaxial strains are investigated by first-principles calculation. Sc₂CO₂ monolayer can withstand stress up to 13.96 N/M and about 14% tensile uniaxial strain limit. Sc₂CO₂ undergoes a transition from semiconductor to metal at −15% uniaxial strain. Sc₂CO₂ under uniaxial strains are only used for the water reduction at pH = 0. Sc₂CO₂ under uniaxial strains of −10%, −7%, −3%, 0%, and 4% within the appropriate pH scope are potential photocatalysts for water redox reaction. Sc₂CO₂ with −15% uniaxial strain is promising anode material, and Sc₂CO₂ with tensile uniaxial strain is more potential cathode material. Wide voltage improves the top quantum capacitance at negative bias under uniaxial strain and keeps the type of electrode materials. Quantum capacitance of Sc₂C with mixed termination (Sc₂CO_0.59F_1.19(OH)_0.22) under uniaxial strain is explored. The introduction of uniaxial strain and mixed termination has little effect on the electrode type of Sc₂CO₂ MXene.     

Investigation on a novel ZnO/TiO2–B photocatalyst with enhanced visible photocatalytic activity

A new type of composite photocatalysts (ZnO/TiO₂–B) with Zinc oxide nanoparticles dispersed on boron doped titanium dioxide was prepared via a sol–gel method. The as-prepared powders were characterized by HRTEM, XRD, XPS, UV–vis DRS, and PL techniques. The results reveal that B³⁺ ions are doped into the TiO₂ lattice in interstitial mode, while ZnO nanoparticles are dispersed on the surface of TiO₂. The absorption of photocatalysts was extended into visible light region and the photogenerated electrons and holes were separated efficiently. Hence, ZnO/TiO₂–B composite photocatalyst exhibits much better photocatalytic activity than those of pure TiO₂ and TiO₂–B on photodegradation of 4-chlorophenol under visible light irradiation.     

V-N共掺纤锌矿ZnO光催化性质的第一性原理研究

基于第一性原理的密度泛函理论对V, N单掺杂和V-N共掺杂ZnO的电子结构和光学性质进行了对比研究. 结果表明:三种掺杂均在可见光区域出现光吸收增强的现象, 其中V-N共掺最为明显; 结合能的计算发现V-N共掺的ZnO体系相对V, N单掺而言结构更稳定, 因此V-N共掺的ZnO是一种稳定而有效的光催化剂. 进一步研究表明, 阴-阳离子共掺的形式可以很好地应用于光电化学领域, 并可以制备出高性能稳定的短波光电材料. 关键词： 基于ZnO的光催化剂 电子结构 光催化性质     

N掺杂纳米ZnO的制备及光催化性能

通过NH3等离子体后处理引入N使其进入到ZnO晶格中,制备出了N掺杂的纳米ZnO光催化剂。通过测试,研究了该样品的结构性质、表面形貌和在不同催化剂浓度、不同反应物浓度、氧气等条件下光催化降解甲基橙的降解效率。分析结果表明,N的掺杂提高了光催化剂的光催化效率。     

玻璃微珠/Ag/TiO2可见光催化剂的制备与表征

通过离子交换法将Ag纳米颗粒负载于玻璃微珠的表面及浅表层,并以钛酸四丁酯的乙醇溶液为前驱体,将TiO₂负载于包含银的玻璃微珠表面,制得一种玻璃微珠/Ag/TiO₂复合光催化剂。由于纳米银的表面等离子体吸收效应,该复合光催化剂具有一定的可见光响应特性。利用XRD、SEM对样品进行表征,可发现玻璃微珠表面形成一层均匀多孔的锐钛矿TiO₂,其粒径均在50 nm左右。由漫反射光谱可得出该催化剂具有较强的可见光吸收,并在降解甲基橙溶液的试验中表现出较好的可见光催化活性。     

掺杂SiO_2-TiO_2光催化剂的制备及对染料废水脱色研究

将ＴｉＯ2 光催化剂用于染料废水脱色处理的工作近几年研究的较多。在可作为光催化剂的Ｎ 型半导体中 ,ＴｉＯ2 性质最优。曹曼等人[1] 用ＴｉＯ2 作催化剂 ,研究了水中活性艳红Ｋ 2Ｇ的光催化氧化机理 ,Ｍａｔｔｅｗｓ[2 ] 将ＴｉＯ2 粉末固定于某一载体上 ,其催化活性比粉末状高 ,ＹｕＺｈｉｇｏｎｇ等[3]对ＴｉＯ2 的催化机理进行了研究。有学者指出 ,由于电子 空穴对产生的时间短 ,为防止其自发合并 ,可在半导体中加入导体物质 ,有利于电子与空穴转移并延长分离时间 ,ＴｉＯ2 的催化活性有明显提高。但在这些研究中都使用了紫外光作为…     

B掺杂TiO2/AC光催化剂的制备及活性

以硼酸和钛酸丁酯为主要原料，以活性炭(AC)为载体。用溶胶-凝胶法制备了B掺杂TiO2／AC光催化剂．用X射线衍射(XRD)、紫外可见漫反射吸收光谱(UV—VIS)对制得的光催化剂进行了表征．以甲基橙水溶液的光催化脱色反应和氧化乐果水溶液的光催化降解反应。考查了不同B掺杂TiO2／AC光催化剂的活性．结果表明，所有B掺杂TiO2／AC光催化剂均为锐钛矿晶相．B的掺杂未导致TiO2／AC光催化剂的吸收带边发生明显的移动．当B-TiO2质量分数分别为2．0％和2．5％时，TiO2／AC光催化剂的活性有明显的提高．B-TiO2质量分数2．0％时活性最高．但是，当B-TiO2质量分数分别为1．5％和3．0％时。TiO2／AC光催化剂的活性降低．B的缺电子特性可能改变了TiO2能带中的电子密度，使光催化反应中光生电子和空穴的俘获方式发生变化；同时。B的缺电子特性也会使光催化剂表面的Lewis酸强度增强，导致表面吸附OH-数量和目标反应物的吸附方式发生变化．这些可能是B-TiO2／AC光催化剂活性发生变化的主要原因．     

Kinetic peculiarities of redox reactions sensitized by colloidal CdS under steady-state irradiation. The effect of adsorption-desorption processes on the reaction

Photoreduction of Methyl Orange dye (MOr) by sodium sulfide was studied under steady-state photolysis ( = 365 nm). The reaction was sensitized by the CdS colloid with the characteristic 5-nm particle size. The quantum yield of the reaction is independent of the light intensity when the latter is less than 5 mW cm^–2. The form of the dependence of the initial quantum yield of the reaction on [MOr] coincides qualitatively with the adsorption isotherm of the dye on the CdS surface. The reaction kinetics under steady-state irradiation were analyzed. The kinetics in solution as a whole are shown to be adequate to those on a single colloidal particle. On the basis of the experimental data, two types of surfaces of the colloidal particles are suggested (open and covered with macromolecules of a colloid stabilizer), which significantly differ in the rate at which they establish an adsorption-desorption equilibrium with the solution.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 244–254, February, 1995.This work was financially supported by the Russian Foundation for Basic Research (Project No. 93-03-4816).