铜离子掺杂CsPbCl3量子点光学性能及稳定性探究

近年来,钙钛矿因其特殊的结构受到广泛的关注。其中,全无机钙钛矿量子点作为下一代发光材料更因其优异的发光性能得到了广泛的研究和关注。但是因为其本身的铅（Pb）元素带来的毒性和较差的稳定性,钙钛矿量子点在生产和应用方面依然面临着诸多阻碍。为了解决这些难题,介绍了一种铜离子（Cu²⁺）B位掺杂CsPbCl₃钙钛矿量子点。采用了热注射的方法成功地将Cu²⁺引入CsPbCl₃钙钛矿量子点中。研究发现,Cu²⁺掺杂CsPbCl₃量子点能够保持初始四方晶体结构。由于Cu²⁺的掺杂,有效地消除了CsPbCl₃量子点的表面缺陷,从而通过辐射途径促进了激子复合,提高了CsPbCl₃量子点的发光性质。通过稳定性对比测试发现,一段时间内,Cu²⁺掺杂CsPbCl₃量子点在水中的发光强度明显高于CsPbCl₃量子点。     

锡掺杂溴铅铯钙钛矿纳米晶的合成、结构及发光性能

为了降低CsPbBr₃钙钛矿纳米晶的Pb²⁺毒性，同时优化Sn²⁺掺杂CsPbBr₃纳米晶的发光性能，采用热注入法合成了Sn²⁺掺杂的Cs Pb_1-xSn_x Br₃纳米晶(x=0.1、0.2、0.3、0.4和0.5)，使用X射线衍射仪(XRD)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)和荧光光谱仪(PL)对所合成纳米晶的物相结构、微观形貌及发光性能进行表征。结果表明，纳米晶中掺杂的Sn元素以Sn²⁺和Sn⁴⁺形式存在，且含有Pb²⁺阳离子空位，当x=0.3时，Sn元素实际掺杂物质的量分数高达43.91%。x=0.1～0.4时，纳米晶为纯单斜相钙钛矿结构，尺寸约16～20 nm，立方块形貌较均匀。Sn²⁺掺杂调控了Cs Pb_1-xSn_x Br₃纳米晶的...     

陈化过程对溴铅甲胺钙钛矿太阳能电池性能影响的研究

氧气氛下的器件陈化对钙钛矿光伏电池的性能有显著影响。本文研究了通过溶液法组装的溴铅甲胺(MAPbBr₃)电池的性能,其中致密的和介孔的Ti O₂作为电子传输层,Spiro-OMeTAD作为空穴传输层。将MAPbBr₃钙钛矿太阳能电池置于湿度<10%的氧气氛暗箱中不同时间,探究O₂对钙钛矿薄膜缺陷的钝化影响,并且采用瞬态光电压(TPV)技术分析陈化前后器件在不同光照时间下的离子迁移。结果表明,陈化处理后,基于MAPbBr₃的器件性能得到明显改善,光电转换效率从4.18%提高到6.73%。这种原因可能归结于钙钛矿材料的缺陷态密度降低,因为在黑暗条件下,O₂在MAPbBr₃钙钛矿太阳能电池中进行扩散,从而起到钝化缺陷的作用。     

基于荧光强度比钙钛矿温敏材料的合成及表征

钙钛矿是指一类陶瓷氧化物,其分子通式为ABO₃。钙钛矿材料特殊的结构,在温敏材料方面具有潜在的应用前景,在近些年来得到了越来越多的关注。在钙钛矿材料中,所掺杂的铋Bi离子根据自身价态和基质的不同可以显示为不同的光色;所掺杂的铕Eu离子发光性质与基质的结构密切相关。不同基质的晶体场影响Bi离子和Eu离子的发光性能,丰富了发光特性。本文通过高温固相法合成钙钛矿结构类型化合物,并利用其发光机制作为测定温度的一种方法。     

CsPbBr3钙钛矿量子点的合成与表征

钙钛矿量子点由于具有独特的电子和发光性质,近几年已成为生物标记、发光二极管、激光和太阳能电池等领域的研究热点。以全无机钙钛矿类量子点为例设计一个研究型综合实验,实验涵盖了CsPbBr₃钙钛矿量子点的制备、表征以及利用钙钛矿量子点荧光性质进行LED器件封装等内容,旨在用简单实验揭开钙钛矿量子点的神秘面纱,让学生感受到科技的魅力。该实验既能让学生更好地了解钙钛矿量子点材料基本知识和应用,还能让学生熟悉液相沉淀法和掌握X射线衍射仪、扫描电子显微镜以及荧光光谱仪等仪器的相关原理及操作,对激发学生科学研究的兴趣和培养学生的综合实践技能、创新思维能力具有积极意义。     

铪金属-有机骨架材料的孔尺寸调控及其吸附性能

利用三种不同长度的有机配体--反丁烯二酸（H₂FUM）、对苯二甲酸（H₂BDC）和联苯二甲酸（H₂BPDC）,合成了一系列具有不同孔尺寸的新型铪（Hf）金属-有机骨架（MOF）材料（Hf-FUM、Hf-BDC和Hf-BPDC）,并考察了CO₂、N₂和CH₄三种气体在这些材料中吸附分离行为。研究结果表明,这三种材料具有和UiO-66（Zr）相同的拓扑结构,且具有很好的热稳定性。Hf-FUM和Hf-BDC的结构在水中能够保持稳定,而Hf-BPDC在水中会发生降解。同时,具有最小孔尺寸的Hf-FUM材料对CO₂/N₂以及CO₂/CH₄体系具有最好的分离性能。这为以后设计用于CO₂分离的新型纳微结构材料提供了参考依据。     

准二维钙钛矿晶体中自限域激子发光机制研究

通过冷却结晶法成功地合成了准二维钙钛矿(C₄H₁₀N)₂(CH₃NH₃)Pb₂Br₇晶体，并研究了该晶体的晶体结构以及自由激子和自限域激子复合发光行为。单晶XRD结构分析表明，该晶体中PbBr₆八面体单元具有极大的结构扭曲。通过光谱分析发现，该准二维钙钛矿材料在紫外光激发下表现为蓝色发光，并且具有两个荧光峰，峰位分别为440 nm和477 nm。其中，较强的荧光峰(440 nm)和较弱的荧光峰(477 nm)分别来源于准二维钙钛矿材料的自由激子和自限域激子的复合发光。该研究结果将有助于深入理解钙钛矿晶体中激子自限域过程和发光机制。     

基于MOFs材料的低碳烃（C1~C3）分离研究进展

低碳烃（C₁~C₃）混合物的分离和纯化是化工过程中最重要且耗能最大的过程单元之一,开发温和条件下低能耗高选择性吸附分离C₁~C₃分子的固体吸附材料迫在眉睫。金属有机框架材料（MOFs）作为一类相对新颖的多孔有机-无机杂化材料,因其可控的拓扑结构和多样的化学微环境,在低碳烃分离和纯化领域受到广泛关注。本文概述了MOFs作为分离和纯化低碳烃气体吸附剂的特性,重点关注了MOFs材料在C₁（CO₂/CH₄）、C₂、C₃烯/烷烃以及烯/炔烃分离领域的应用进展。首先归纳了MOFs材料在C₁~C₃烃类物质分离过程中的三种常见分离机制,并据此回顾了近年来MOFs材料对常见C₁~C₃烃类分子的吸附及分离性能;分析了MOFs材料在C₁~C₃烃类物质分离过程中的构效关系,总结了MOFs材料的孔道尺寸/形状、骨架柔性和表面功能的调控理念与方法,并提出MOFs材料成本高、水热稳定性差、主客体关系难以精准探测等制约其应用发展的现状。文章指出未来研究重点为开发低成本多样化专一性的新型配体,构造复合型吸附剂,并明确吸附分离过程中分离体系主客体性质,为MOFs材料用于低碳烃分离的定向设计提供了探索方向。     

MgAl2O4:Ce荧光粉辐照合成及发光机理研究

通过伽马射线辐照辅助聚丙烯酰胺凝胶法合成了MgAl₂O₄和MgAl₂O₄:Ce荧光粉。通过X射线粉末衍射仪（XRD）、透射电子显微镜（TEM）、紫外可见分光光度计和荧光分光光度计研究了MgAl₂O₄:Ce荧光粉的晶体结构、表面形貌、光学性质和发光性质;基于实验所获得的结果,分析了纳米级MgAl₂O₄:Ce荧光粉的发光机理。实验结果表明:采用伽马射线辐照辅助聚丙烯酰胺凝胶法制备纯相MgAl₂O₄和MgAl₂O₄:Ce荧光粉的结晶温度要比传统聚丙烯酰胺凝胶法低100 ℃左右;MgAl₂O₄:Ce荧光粉的平均颗粒尺寸为14 nm,Ce离子掺杂后导致样品颗粒细化;Ce离子的掺入,降低了MgAl₂O₄的能带值,改善了其颜色性质和发光性质;当采用275 nm的光去激发MgAl₂O₄:Ce荧光粉时,获得了425 nm和464 nm的蓝光发射。通过能量传递原理分析认为,杂质缺陷（Ce³⁺）在整个发光过程中扮演了重要角色。MgAl₂O₄:Ce作为一种抗辐射能力强的荧光粉,在空间照明领域具有很好的应用前景。     

锂离子电池负极材料磷酸钛锂研究进展

NASICON结构的磷酸钛锂[LiTi₂（PO₄）₃]作为新型的锂离子电池负极材料,具有环境友好、循环性能好、优异的热稳定性等优点,被认为是最具有应用前景的负极材料。LiTi₂（PO₄）₃具有138 mA·h/g的理论容量和2.5 V的平稳放电平台,但是LiTi₂（PO₄）₃电子电导率低、锂离子扩散系数小等缺点限制了其实际应用。因此,针对以上缺点,众多研究者通过对LiTi₂（PO₄）₃进行改性,极大地提高其电子电导率和锂离子扩散系数。简单介绍了LiTi₂（PO₄）₃的结构与性能,主要从制备方法和改性方法两方面综述了近年来的研究进展,并指出了LiTi₂（PO₄）₃材料目前研究存在的问题,展望了未来的应用前景。     

Enhanced charge extraction for all-inorganic perovskite solar cells by graphene oxide quantum dots modified TiO2 layer

All-inorganic cesium lead bromide (CsPbBr₃) perovskite solar cells have been attracting growing interest due to superior performance stability and low cost. However, low light absorbance and large charge recombination at TiO₂/CsPbBr₃ interface or within CsPbBr₃ film still prevent further performance improvement. Herein, we report devices with high power conversion efficiency (9.16%) by introducing graphene oxide quantum dots (GOQDs) between TiO₂ and perovskite layers. The recombination of interfacial radiation can be effectively restrained due to enhanced charge transfer capability. GOQDs with C-rich active sites can involve in crystallization and fill within the CsPbBr₃ perovskite film as functional semiconductor additives. This work provides a promising strategy to optimize the crystallization process and boost charge extraction at the surface/interface optoelectronic properties of perovskites for high efficient and low-cost solar cells.     

制备方法对钙钛矿薄膜结构及形貌的影响

采用液相连续沉积法制备了有机/无机杂化钙钛矿（CH₃NH₃PbI₃,MAPbI₃）光吸收层,并研究了不同薄膜形貌、晶体结构和光吸收能力对钙钛矿太阳能电池性能的影响。结果表明：制备工艺对吸光层形貌和器件光电性能产生很大的影响。相对于分步浸渍法,分步旋涂法（分步旋涂无机相碘化铅PbI₂和有机相甲胺碘CH₃NH₃I前驱液）和气体辅助修复法（新制初始MAPbI₃薄膜在室温下置于甲胺气氛中）能有效改善薄膜形貌和平整度,获得覆盖完全的均匀钙钛矿吸光层。同时,进一步分析了初始MAPbI₃膜的形貌对气体修复法制备全覆盖平整钙钛矿薄膜的影响,发现初始钙钛矿膜的形貌对最终修复后的膜层形貌没有影响,这可能是因为不同初始MAPbI₃膜经甲胺气体处理后均形成一种"甲胺铅化碘-甲胺"（MAPbI₃·MA）的液态中间相,再经退火处理后均获得平整、致密的钙钛矿膜层,极大地提高了MAPbI₃的结晶度和薄膜均匀性,从而提高活性层的吸光率、光电流和电池效率。     

Catalytic oxidation over lanthanum-transition metal perovskite materials

The thrust of this work is to follow the defect chemistry of the simple LaCoO₃ system in an attempt to probe if there is a relationship between the defect chemistry and the activity of this perovskite-type material to catalytic methane combustion. A simple flow-through reactor has been used to study the combustion of methane between room temperature and 1100°C. Using a gel-type precipitation method it has been proved possible to synthesise a single phase perovskite material with a bulk La:Co metal atom ratio of 1:1.1. PXRD, Rietveld analysis and density measurements show that the perovskite phase is non-stoichiometric with a deficiency of lanthanum ions in the lattice. This material is rather ineffective as a catalytic material. A more active form can be prepared at a La:Co metal atom ratio of 1:1 when a mixed phase (perovskite/lanthana) is produced. This material exhibits both higher activity to methane combustion and the storage/evolution of oxygen (as measured using DSC and TPD techniques).

The results of activity tests have been rationalised using XPS where large amounts of O⁻ species are seen at the surface. It is proposed that these ions occupy anion vacancies created to compensate for the reduced cation charge in the lattice. This is not possible for the single phase material where vacancies are compensated for by the presence of valency changes of cobalt and/or oxygen.

Further work has been carried by doping of the perovskite with cations of valencies +2, +3 and +4 in an attempt to control the non-stoichiometry. In this way, it has been proved possible to provide simple synthetic routes to active methane combustion catalysts.     

Honeycomb supported perovskite catalysts for ammonia oxidation processes

Pechini route (M.P. Pechini. U.S. Patent no. 3,330,697 (1967)) was used for supporting perovskite – like systems LaBO₃ (B = Mn, Fe, Co, Ni, Cu) on thin-wall (0. 35 mm) cordierite honeycomb support with low thermal expansion coefficient to prepare stable to thermal shocks supported catalysts for high-temperature processes of ammonia oxidation into NO in nitric acid production. In this preparation route, perovskites (2–6%) have nearly uniform distribution in the walls as well as form surface grainy perovskite layer 2–3 μm thick that may be also important for the high temperature processes occurring at short contact times. Cordierite supported lanthanum manganite and cobaltite are the most active in the reaction of ammonia oxidation into NO especially when supported twice or on a secondary sublayer (Ln₂O₃, ZrO₂, MeO, LaBO₃).     

掺杂离子的种类对介孔La0.6A0.4NiO3钙钛矿催化剂的结构与催化活性的影响

以十六烷基三甲基溴化铵（CTAB）为模板剂,用共沉淀法分别制备了介孔La_0.6A_0.4NiO₃（A=Ce、Sr、Y、Nd、Pr）钙钛矿复合氧化物,用XRD、SEM、FTIR、BET和程序升温技术等对复合氧化物的晶相结构、表面形貌、表面积、孔径分布及表面性能等进行了表征,同时在蔗渣高压液化反应中探讨了A位离子掺杂种类对介孔La_0.6A_0.4NiO₃催化活性和液化产物分布及液化油含量的影响。结果表明,掺杂的A位离子均能进行不同程度的同晶取代,其中掺杂的Pr³⁺能较好的与La³⁺发生同晶取代,且具有较大的比表面积和孔径分布,表面存在较强的氧物种传导性和碱性中心,在蔗渣高压液化反应中具有较高的液化油产率和较低的残渣率,生物质油的主要成分为乙酰柠檬酸三丁酯、柠檬酸三正丁酯、对乙基苯酚、6-乙基-3-肽酸酯,有利于提高油品的质量。     

Lead oxide enables lead volatilization pollution inhibition and phase purity modulation in perovskite quantum dots embedded borosilicate glass

Embedding all-inorganic cesium lead halide CsPbX₃ (X=Cl, Br, I) perovskite quantum dots (PQDs) PQDs into glass is one of the most effective strategies to improve their optical, thermal and chemical stabilities. Herein, by using PbO instead of PbBr₂ as the lead source, it is effective to lower the melting temperature and reduce the volatilization pollution from lead halide raw materials. Thus, a high-purity CsPbBr₃ PQDs embedded glass with 71.5 % PLQY was successfully prepared. The thermal stability, and photo-aging properties were also improved. By simply changing the halogen element, the red and blue CsPbX₃ PQDs embedded glasses were successfully prepared. The white LED fabricated by coating obtained green/red CsPbX₃ PQDs embedded glass on a blue chip displays high color gamut of 121.9 % NTSC standard and >91.1 % Rec. 2020 standard, which embodies the great potential of PQDs embedded glass in lighting and display fields.     

Ce的掺杂对负载型催化剂LaMnO3/赤铁矿脱硝性能的影响

采用柠檬酸络合浸渍法,通过对A位离子进行掺杂或取代和调节Ce的掺杂量,制备了一系列的负载型催化剂La_1-xA_xMnO₃/赤铁矿（A=Ce、Co,x=0/0.1/0.2/0.3）,并将催化剂应用于固定床NH₃-SCR脱硝。采用XRD、BET、XRF、H₂-TPR、NH₃-TPD等表征手段对催化剂进行分析和表征。结果表明,Ce的掺杂提高了催化剂LaMnO₃/赤铁矿的低温脱硝效率和拓宽了催化剂的活性温度窗口,如La_0.8Ce_0.2MnO₃/赤铁矿催化剂,在180℃时,脱硝效率就高达98%,且在150～250℃温度区间的脱硝效率均在90%以上。结合表征分析证明,稀土元素Ce的适量掺杂,明显提高了LaMnO₃/赤铁矿催化剂的氧化还原能力和催化剂表面NH₃分子的吸附能力;稀土元素Ce的适量掺杂也改善了催化剂比表面积,也使活性物质高度分散在载体表面上。     

Role of oxygen vacancies and Sr sites in SrCo0.8Fe0.2O3 perovskite on efficient activation of peroxymonosulfate towards the degradation of aqueous organic pollutants

Metal-based perovskite oxides have contributed significantly to the advanced oxidation processes (AOPs) due to their diverse active sites and excellent compositional/structural flexibility. In this study, we specially designed a perovskite oxide with abundant oxygen vacancies, SrCo_0.8Fe_0.2O₃ (SCF), and firstly applied it as a catalyst in peroxymonosulfate (PMS) activation towards organic pollutants degradation. The result revealed that the prepared SCF catalyst exhibited excellent performance on organic compounds degradation. Besides, SCF showed much better activity than La_0.5Sr_0.5Co_0.8Fe_0.2O₃ (LSCF) in terms of reaction rate and stability for the degradation of the organic compounds. Based on the analysis of scanning electron microscope, transmission electron microscope, X-ray diffraction, N₂ adsorption–desorption, X-ray photoelectron spectroscopy and electron paramagnetic resonance, it was confirmed that the perovskite catalysts with high content of Sr doping at A-site could effectively create a defect-rich surface and optimize its physicochemical properties, which was responsible for the excellent heterogeneous catalytic activity of SCF. SCF can generate three highly active species: ¹O₂, SO^-₄· and ·OH in PMS activation, revealing the degradation process of organic compounds was a coupled multiple active species in both radical and nonradical pathway. Moreover, it was mainly in a radical pathway in the degradation through PMS activation on SCF and SO^-₄· radicals produced were the dominant species in SCF/PMS system. This study demonstrated that perovskite-type catalysts could enrich OVs efficiently by doping strategy and regulate the PMS activation towards sulfate radical-based AOPs.     

Sr掺杂强化LaCo0.5Cu0.5O3型钙钛矿活化过一硫酸盐的性能

采用溶胶-凝胶法制备A位掺Sr的La_xSr_1-xCo_0.5Cu_0.5O₃钙钛矿增强传统B位掺杂钙钛矿活化过一硫酸盐（PMS）的能力。本文选取效果最好的La_0.7Sr_0.3Co_0.5Cu_0.5O₃型钙钛矿为研究对象,以偶氮染料AO7为目标污染物,考察了钙钛矿投加量、PMS浓度、pH和染料废水中常见Cl^-对La_0.7Sr_0.3Co_0.5Cu_0.5O₃/PMS体系降解AO7的影响,并测试了材料的重复利用性和矿化能力。结果表明,La_0.7Sr_0.3Co_0.5Cu_0.5O₃/PMS降解AO7的速度随着材料投加量和PMS浓度的增加而加快,在中性条件下反应速度最快且矿化率良好。该体系主要活性物种之一为·OH,但Sr掺杂后钙钛矿的O空位增多使得¹O₂也参与到降解过程之中。