Bi2MoO6/Ag3PO4复合光催化剂的制备及其光催化性能EI北大核心CSCD

以片状的Bi2MoO6为前驱物,通过原位化学沉淀法制备了Bi2MoO6/Ag3PO4复合光催化剂,考察了其光催化降解罗丹明B（Rh B）的活性。研究表明：Bi2MoO6和Ag3PO4复合可显著提高光催化活性,Bi2MoO6和Ag3PO4匹配的能级结构有利于光生电子和空穴的分离,延长光生载流子的寿命;当Bi2MoO6的质量分数为35%时,复合光催化剂具有最佳的光催化活性。     

稀土钙钛矿锰氧化物催化活性的研究概况

钙钛矿型复合氧化物（ABO3）具有独特的电磁性质和氧化还原催化活性。受主掺杂的ABO3（A=RE,B=Mn,B,Co,Ni）具有较高的电导率,常用作固态氧燃料电池的阴极,但有关其光催化活性的研究却很少见报。如何提高光生载流子的分离效率,实现光催化剂对可见光的响应,开拓光催化剂更广泛的应用领域,是研究者主要思考的一些问题。     

Ag3PO4/AgI光催化剂的制备及降解2-氨基-4-乙酰氨基苯甲醚机理

研究了Ag₃PO₄复合棒状AgI光催化剂的制备及降解2-氨基-4-乙酰氨基苯甲醚（AMA）的性能和机理,利用X射线衍射（XRD）、扫描电镜（SEM）、紫外可见漫反射（UV-Vis）、光电子能谱（XPS）等方法对合成样品的物相组成和形貌结构进行了表征。通过可见光催化降解AMA来评价光催化剂的催化性能。实验结果显示,Ag₃PO₄/AgI复合光催化剂比Ag₃PO₄和AgI单体具有更强的光催化氧化与还原能力,其中以I和P的比例为1∶5时效果最佳,且在五次循环使用之后仍有较好的光催化活性。自由基捕获实验证明光催化过程中光生空穴（h⁺）是主要的活性物种。投加量为30mg、光照时间60min的条件下可将AMA几乎完全去除。本文研究结果为构筑新型可见光光催化剂提供了新视角,为促进光催化降解有机污染物提供了新途径。     

Fe掺杂Bi12TiO20光催化剂的制备及光催化性能

采用水热法制备Fe元素掺杂的Bi12TiO20光催化剂，对Bi12TiO20结构进行修饰，使用X射线衍射（XRD）、紫外-可见漫反射（UV-Vis DRS）、扫描电镜（SEM）、氮气吸附脱附、X射线光电子能谱（XPS）对光催化剂的形貌微观结构和化学价态进行表征，并应用在光催化降解亚甲基蓝（MB）上。实验结果表明，当Fe的掺杂量为5%时，催化剂的投加量为0.05g，对10mg/L的MB的降解率达到98.949%。经过Fe掺杂后，Fe-Bi12TiO20光催化剂形成了新的杂化能级，吸收带边界发生红移，进而提高催化剂的光催化活性，Fe是以+3和+2价掺杂于Bi12TiO20的晶体中。Fe-Bi12TiO20光催化剂，经过重复使用5次后，对MB的降解率仍然可以达到88%以上，具有优秀的光催化稳定性能。h+和·O2-是光催化降解过程中的主要活性物种。本文为Bi12TiO20材料的掺杂改性研究提供了参考。     

Bi_2MoO_6/Ag_3PO_4复合光催化剂的制备及其光催化性能

以片状的Bi_2MoO_6为前驱物,通过原位化学沉淀法制备了Bi_2MoO_6/Ag_3PO_4复合光催化剂,考察了其光催化降解罗丹明B(Rh B)的活性。研究表明:Bi_2MoO_6和Ag_3PO_4复合可显著提高光催化活性,Bi_2MoO_6和Ag_3PO_4匹配的能级结构有利于光生电子和空穴的分离,延长光生载流子的寿命;当Bi_2MoO_6的质量分数为35%时,复合光催化剂具有最佳的光催化活性。     

Ni、B共掺杂TiO2-陶粒表征及降解甲基橙研究

采用溶胶-凝胶法制备了陶粒负载Ni2O3和B元素共掺杂纳米TiO2可见光催化剂。XRD和FT-IR表征结果表明,B的掺杂以取代晶格中的O离子的形式存在,Ni以Ni2O3形式游离于TiO2表面存在;光催化试验结果表明,B、Ni的掺杂使Bx-TiO2-(Ni2O3)y-陶粒催化剂中TiO2粒径减小、比表面积增大,同时抑制电子与空穴对的复合,有利于电荷分离,从而使催化剂光催化活性提高。以甲基橙为目标污染物,探讨了复合光催化剂光催化氧化降解COD的规律,结果表明,在600℃温度下焙烧的催化剂具有最佳光催化活性,优化的Ni、B元素掺杂质量分数均为3.0%;催化剂最佳投加量为300 g/L,在强酸条件下COD的去除率最大。     

BiOCl/g-C3N4异质结催化剂可见光催化还原CO2

以KCl、Bi（NO₃）₃和类石墨氮化碳（g-C₃N₄）为前体,采用水热法成功制备了BiOCl/g-C₃N₄异质结光催化剂,并进行可见光催化还原CO₂,考察了催化剂的活性及稳定性,同时研究BiOCl：g-C₃N₄（摩尔比）、催化剂用量和光照强度对光催化还原CO₂的影响。结果表明,在水蒸气的存在下,BiOCl/g-C₃N₄较纯BiOCl和g-C₃N₄具有更高的光催化还原CO₂活性,在催化剂用量为0.1 g,光照强度为2.413×10^-6 einstein·min^-1·cm^-2,BiOCl：g-C₃N₄摩尔比为1：1的异质结催化剂显示了最高的光催化还原CO₂活性,且可见光催化剂在5次套用实验后其活性基本不变。基于X射线衍射（XRD）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、X射线光电子能谱（XPS）、比表面积测试（BET）和紫外-可见（UV-vis）吸收光谱表征,可以推断BiOCl和g-C₃N₄之间形成的p-n结能有效分离光生电子和空穴,是增强光催化剂活性的主要原因。     

Fe3+掺杂Bi2MoO6光催化剂的合成及其活性研究

以钼酸铵、硝酸铋和硝酸铁为原料,采用水热/溶剂热法合成了铁掺杂的钼酸铋光催化剂,用X-射线粉末衍射、扫描电镜及紫外-可见吸收光谱等进行表征,并以罗丹明B为模型污染物,考察了纳米钼酸铋对罗丹明B溶液的光催化降解活性;以噻吩作为典型的含硫污染物,评价样品的光催化氧化脱硫活性。结果表明,Fe元素掺杂导致Bi2 MoO6的尺寸下降,比表面积增大;Fe掺杂,Bi2 MoO6吸收边发生红移;光催化活性与Fe元素的掺杂浓度有关,当掺杂量为0.5%时,活性最高;Fe掺杂Bi2MoO6对模拟汽油具有较好的脱硫活性,模拟可见光照射3 h,可使用模拟汽油的硫含量降低至70μg/g以下,脱硫率达到89%。     

Fe^3＋掺杂Bi_2MoO_6光催化剂的合成及其活性研究

以钼酸铵、硝酸铋和硝酸铁为原料,采用水热/溶剂热法合成了铁掺杂的钼酸铋光催化剂,用X-射线粉末衍射、扫描电镜及紫外-可见吸收光谱等进行表征,并以罗丹明B为模型污染物,考察了纳米钼酸铋对罗丹明B溶液的光催化降解活性;以噻吩作为典型的含硫污染物,评价样品的光催化氧化脱硫活性。结果表明,Fe元素掺杂导致Bi2 MoO6的尺寸下降,比表面积增大;Fe掺杂,Bi2 MoO6吸收边发生红移;光催化活性与Fe元素的掺杂浓度有关,当掺杂量为0.5%时,活性最高;Fe掺杂Bi2MoO6对模拟汽油具有较好的脱硫活性,模拟可见光照射3 h,可使用模拟汽油的硫含量降低至70μg/g以下,脱硫率达到89%。     

钙钛矿型LaFeO3和SrFeO3的光催化性能

采用柠檬酸法合成钙钛矿型复合氧化物LaFeO3和SrFeO3,并以其为光催化剂对不同水溶性染料进行光催化降解实验.结果表明:SrFeO3的光催化活性明显高于LaFeO3,这与A位离子(La3+,Sr2+)的电子构型的不同有关.     

Partial Oxidation of Hydrocarbons and Oxygenated Compounds on Perovskite Oxides

Research of perovskite oxide catalysts (AB03) with a rare-earth ion as an A-site and a transition metal ion as a B-site has been concentrated on the complete oxidation of hydrocarbons, particularly related to exhaust control, and revealed that they are potential catalysts for deep combustion of hydrocarbons (1). The complete oxidation activities have been reported to be mainly controlled by the physicochemical property of the B-site metal cations such as the electronic configuration of d-electron (2), the binding energy of B-0 bond (3) and the stabilization energy of the crystal field (4), rather than the relatively small and less important effect of the rare-earth ion of the A-site (5) and also improved by the substitution of other metal cations for A- or B-site (6,7). Although it is difficult to find many investigations on the application of perovskite-type oxides to partial oxidation, in this chapter, the movement to the partial oxidation of hydrocarbons and oxygenated compounds using various perovskite oxides as catalysts is summarized.     

Heterogeneous-Homogeneous Mechanism of Catalytic Oxidation

Research of perovskite oxide catalysts (AB03) with a rare-earth ion as an A-site and a transition metal ion as a B-site has been concentrated on the complete oxidation of hydrocarbons, particularly related to exhaust control, and revealed that they are potential catalysts for deep combustion of hydrocarbons (1). The complete oxidation activities have been reported to be mainly controlled by the physicochemical property of the B-site metal cations such as the electronic configuration of d-electron (2), the binding energy of B-0 bond (3) and the stabilization energy of the crystal field (4), rather than the relatively small and less important effect of the rare-earth ion of the A-site (5) and also improved by the substitution of other metal cations for A- or B-site (6,7). Although it is difficult to find many investigations on the application of perovskite-type oxides to partial oxidation, in this chapter, the movement to the partial oxidation of hydrocarbons and oxygenated compounds using various perovskite oxides as catalysts is summarized.     

Tailoring Curie temperature and dielectric properties by changing the doping sites of Y ions in (Ba,Ca)(Zr,Ti)O3 ceramics

Doping rare earth element significantly influences electrical properties of BaTiO₃-based ceramics. In this work, Y-doped (Ba_0.95Ca_0.05)(Zr_0.19Ti_0.81)O₃ (BCZT) ceramics are investigated by comparing the microstructure, dielectric and conduction properties of BCZT with different doping-sites of Y ions, A-site, B-site and A/B-site, respectively. Y ions are successfully incorporated into the BCZT lattice, irrespective of the doping sites. A-site doping has marginal effect on the grain size and Curie Temperature, however, B-site doping leads to a decreased grain size and Curie temperature with doping concentration. For A/B-site doping sample, the grain size and Curie temperature are dependent on doping concentration. Furthermore, the T_c regulation mechanism is discussed based on the average size effect (<R>), variance effect (σ²), the local electric field and tolerance factor (t) theories. This work provides a potential strategy for adjusting T_c and improving diele_ctric performance by tuning the doping sites and selecting appropriate rare earth elements with suitable size.     

AB位掺杂对La2NiO4同时催化还原脱除NOx和柴油机碳烟颗粒性能的影响

用溶胶凝胶法制备了一系列的La2NiO4型氧化物催化剂,考察了其同时催化还原脱除NOx和碳烟颗粒的性能,结果表明未改性的La2NiO4具有较好的催化活性,300℃时NO的转化率可达42%,选择性为54%,氧气对于目标反应具有一定的促进作用。为了考察A、B位掺杂改性对其催化性能的影响,分别对A位进行了Sr、Ba掺杂,B位进行了Mn、Fe掺杂,研究表明A、B掺杂改性会起到不同的作用,A位改性主要影响反应的选择性,B位改性主要影响反应的温度。A位Sr改性可以提高催化剂的催化活性和选择性,300℃时NO的转化率从42%提高到64%,选择性从54%提高到69%。     

Understanding microwave dielectric properties of Pb-based complex perovskite ceramics via bond valence

Correlations between microwave dielectric properties and the dielectric polarizabilities related to the bond valences of A- and B-site ions in Pb-based complex perovskite ceramics have been investigated. With the decrease of A-site bond valence, the dielectric constants were higher than those obtained from the dielectric additivity rule due to the rattling behavior of A-site ions. The temperature coefficient of the resonant frequency (TCF) depended strongly on the bond valences of the A- and B-sites, as well as the tolerance factor (t) in the perovskite structure. In the tilted region (t<1.0), the tilting of the oxygen octahedra increased and the TCF decreased because of the increasing bond valence of the B-site. Also, the dependence of TCF on the bond valence of the A-site was similar to its dependence on the tolerance factor (t).     

Simultaneous removal of nitrogen oxides and diesel soot particulates catalyzed by perovskite-type oxides

Perovskite-type oxides (ABO₃) catalyzed the simultaneous removal of NO_x and diesel soot particulates in the presence of oxygen, and were superior to transition metal simple oxides in the selectivity for NO_x reduction. Although the catalytic activity of perovskite-type oxides depended on both A-site and B-site cations, the substitution of potassium at A sites prominently promoted the oxidation of soot and the reduction of NO_x.     

Simultaneous removal of NO and carbon particulates over lanthanoid perovskite-type catalysts

The simultaneous removal of carbon particulate and NO_x has been studied over perovskite-type oxides prepared by malic acid method. The catalysts were modified to enhance the activity by substitution of metal into A- or B-site of perovskite oxide. In the LaCoO₃ catalyst, the partial substitution of Cs into A-site enhanced the catalytic activity in the combustion of soot particulate and NO reduction. In La_1−xCs_xCoO₃ catalysts, the ignition temperature of carbon particulate decreases with increasing x values and shows almost constant values at substitution of x>0.2 and NO conversion also shows the similar tendency. In the Cs-substituted oxide, the ignition temperature of carbon particulate slightly decreased in the order Co>Mn>Fe of B-site metal cation but NO conversion showed almost similar values. With increasing NO concentration, NO conversion decreased but the ignition temperature moved to high temperature when the NO concentration was higher than 1000 ppm. The carbon particulate played an important role on the reduction of NO, but NO had little effect on the oxidation of carbon particulate.     

A- and B-compensated PLZT x/90/10: Sintering and microstructural analysis

Structure–property relationship has been performed in the lanthanum-modified lead–zirconate–titanate (PLZT) with a lanthanum content of 6 and 10 at.% and a Zr/Ti ratio of 90/10 as a function of A- and B-compensation model. The X-ray powder-diffraction analysis, electron microscopy, energy-dispersive spectroscopy, density measurements and sintering behavior have evidently demonstrated that it is possible to tailor the microstructural properties of PLZT with using selected type of the compensation. The densification of B-site compensated PLZT occurs at lower temperatures and leads to higher density when compared to A-site compensated PLZT. A presence of PbO at the grain boundaries in B-site compensated PLZT and the lack of it in A-site compensated PLZT leads to different sintering mechanism. The dielectric response characteristics of A- and B-site compensation model do not vary significantly.     

Ba1-3x/2Lax(Mg1/3Ta2/3)O3陶瓷的微波介电性能

采用固相合成法制备了Ba1-3x/2Lax(Mg1/3Ta2/3陶瓷,研究了La掺杂对钽镁酸钡的结构和微波介电性能的影响.结果表明:A位取代能改进其烧结性能.在x≤0.02时,烧结样品为单相的钙钛矿结构,B位离子1:2有序;当x>0.02时出现第二相Ba0.5TaO3.B位离子有序度随着x的增大先增加后减小,在x=0.04时出现最大值.x≤0.02时介电常数变化较小,而后其值逐渐增大.品质因数与谐振频率的乘积(Q×f)值随着x的增大先增大后减小,在x=0.02时取得最大值;谐振频率温度系数(τf)值随着x增大而增大.     

偏压下弛豫型铁电陶瓷有效介电系数稳定方法的研究

本研究利用调整有效介电常数的互补公式