铁电材料光催化的研究进展

光催化材料因能利用太阳能净化环境而备受关注。一些铁电材料可以被太阳光激发,实现目标物的降解,且其自发极化有望解决光催化产生电子和空穴的复合问题,成为光催化材料的研究热点之一。对具有铋层状结构、钙钛矿结构、R3c空间群的菱形结构、层状钙钛矿结构和烧绿石结构的铁电材料光催化的研究现状进行了归纳和综述。     

可见光响应金属氧化物光催化剂的研究进展

研究开发可见光化的光催化剂成为当前光催化剂研究中的重要课题.综述了近年来可见光响应多元金属氧化物光催化剂的研究进展,重点描述了层状、钙钛矿型、尖晶石型、软铋矿型、烧绿石型以及白钨矿型金属氧化物光催化材料的电子结构与可见光光催化活性关系,它们的高可见光催化活性来源于自身的晶体结构和电子结构所引起的禁带窄化和光生电子空穴的有效分离,并对该领域今后的研究工作提出了个人建议.     

钛酸锶光催化材料研究进展

近年来,钙钛矿型化合物以其特有的结构在光催化领域成为国内外研究的热点。钛酸锶(SrTiO3)是一种典型的钙钛矿型复合氧化物,具有稳定性高、无毒性,载流子迁移率高,光催化活性高等特点,作为半导体有低阻的电子运输结构和对小分子高效的氧化还原能力,是一种极具开发潜力和应用前景的光催化材料。主要介绍了SrTiO3材料的结构、制备方法与光催化机理,并对近年来SrTiO3在光催化领域的改性研究进行综述。最后在现有研究成果的基础上,对SrTiO3光催化材料的未来发展动向进行简要分析,有助于研究者取得进一步突破。     

钽掺杂对层状钙钛矿镧钛酸钾光催化性能的影响

用高温固相法制备Ta5 掺杂的K2-xLa2Ti3-xTaxO10(x=0.1-1.0)系列层状钙钛矿,用XRD,UV-VIS和BET等方法对样品进行表征,研究了钽取代钛对层状钙钛矿镧钛酸钾光催化性能的影响.结果表明,掺杂Ta降低了半导体颗粒能隙,拓展了光响应范围,提高了光催化活性.随着Ta掺杂量的增加,少量Ta团聚覆盖在材料颗粒表面,x增至0.8时发生相转变,导致光催化活性下降.结果表明,K1.9La2Ti2.9Ta0.1O10具有最佳光催化活性.     

钽掺杂对层状钙钛矿镧钛酸钾光催化性能的影响

用高温固相法制备Ta^5＋掺杂的K2-xLa2Ti3-xTaxO10（x=0．1—1．0）系列层状钙钛矿,用XRD,UV—VIS和BET等方法对样品进行表征,研究了钽取代钛对层状钙钛矿镧钛酸钾光催化性能的影响．结果表明,掺杂,Ta降低了半导体颗粒能隙,拓展了光响应范围,提高了光催化活性．随着Ta掺杂量的增加,少量,Ta团聚覆盖在材料颗粒表面,x增至0．8时发生相转变,导致光催化活性下降．结果表明,K1.9La2Ti2．9Ta0.1O10具有最佳光催化活性．     

凝胶-燃烧法制备LaNiO3和La2NiFeO6光催化剂的比较研究

采用凝胶-燃烧法制备稀土单钙钛矿型LaNiO_3和双钙钛矿型La_2NiFeO_6光催化剂,利用X射线衍射、BET、红外光谱、扫描电镜进行了表征,并在可见光下以亚甲基蓝为模拟降解物进行了光催化研究。结果表明:钙钛矿LaNiO_3的结构是斜方六面体,而双钙钛矿La_2NiFeO_6的结构是立方体;La_2NiFeO_6的光催化活性高于LaNiO_3,这与二者之间的结构和表面性质的差异有关。     

半导体光解水研究进展

概述了半导体光解水的原理、光催化剂及光催化体系等方面的研究进展,主要介绍了TiO2、层状结构的铌酸盐K4Nb6O17、InTaO4和碱性金属钽酸盐ATaO3(A=Li、Na、K)等光催化剂,并展望了该领域未来的研究.     

可见光降解有机污染物催化剂研究进展

光降解水中有机污染物是解决环境问题非常有前途的策略。主要介绍了近年来光催化降解有机污染物的国内外最新研究进展,重点介绍了钛酸盐光催化剂、钽酸盐光催化剂、铌酸盐光催化剂、无机层状化合物、金属硫化物、Z型光催化反应体系。着重总结了金属硫族化合物催化剂降解有机污染物存在的问题及可行的解决方案,并对以后可见光催化降解有机物的研究发展趋势进行了展望。     

层状粘土矿物负载TiO_2光催化材料的合成与应用研究进展

TiO_2作为一种环境友好光催化材料在环境治理领域已显示出广阔的应用前景,其中易于分离和回收的负载型TiO2_光催化材料具有一定优势并被寄予厚望。层状粘土矿物由于具有特殊的层结构、大的长径比、较好的吸附性等优良特性,可作为一种较为理想的纳米TiO_2载体。综述了国内外层状粘土矿物负载TiO_2复合光催化剂的最新研究进展,重点介绍了基于蒙脱石、高岭石等几种典型层状粘土矿的负载型纳米TiO_2的合成方法以及在环境污染物治理方面的应用。     

有机-无机分子组装层状类钙钛矿结构与特性

有机-无机分子组装层状类钙钛矿材料在分子水平上结合了有机组分和无机组分的优点，无机组分通过强的共价键或离子键形成扩展的骨架，并将有机组分填入框架中形成有机层与无机层交替的结构，具有某些电学、光学、磁学等特性。在此主要介绍了有机-无机分子组装层状类钙钛矿材料的结构及相关的性能研究。     

低维钙钛矿:兼具高效率和稳定性的新型太阳能电池光吸收层候选材料

使用有机无机杂化钙钛矿材料作为光吸收层的钙钛矿太阳能电池自进入人们的视野以来,其制备工艺和器件结构不断得到优化,短短几年内效率取得了非常可观的增长。与此同时,这种基于三维钙钛矿材料的电池的缺点也越来越突出,尤其是材料的不稳定性,严重阻碍了其发展。低维钙钛矿材料具有有机胺层与无机层(金属卤化物钙钛矿晶体)之间相互交替的低维(层状)结构,其中被有机胺隔开的独立钙钛矿层中八面体的层数n越小,钙钛矿越接近二维结构。相比传统三维钙钛矿结构,低维钙钛矿材料应用于光伏器件具有两大优势:(1)耐湿性、光热稳定性大大增强;(2)可以通过改变n和插入的有机胺的种类来实现光学及电学性质的可调性。然而,低维钙钛矿具有较大的光学带隙,有机胺的引入降低了载流子迁移率,导致低维钙钛矿电池的效率明显低于三维钙钛矿电池。因此,近三年来除研究钙钛矿层数对材料性质和器件性能的影响外,研究者们主要从选择合适的有机胺和优化薄膜制备工艺方面不断尝试,并取得了丰硕的成果,在充分发挥低维钙钛矿稳定性优势的同时大幅提升了器件效率。目前,低维钙钛矿太阳能电池的光电转换效率已由2014年的4.37%跃升至13.7%。在较高效率的低维钙钛矿太阳能电池中已取得成功应用的有机胺类包括苯乙胺(PEA)、正丁胺(n-BA)、异丁胺(iso-BA)、聚乙烯亚胺(PEI)等。其中PEA应用得最早;n-BA是运用在目前为止最高效的低维钙钛矿电池中的有机胺;而PEI插层形成的低维钙钛矿拥有相对更小的光学带隙和更高的耐湿性,但载流子的传输会受到更大的限制。低维钙钛矿薄膜的制备起初主要采用简单的一步旋涂法,但此法所得的低维钙钛矿平行于基底生长,器件效率很低。近两年的研究工作将基底预热、浸泡、反溶剂滴加等手段引入到钙钛矿旋涂工艺中,实现了低维钙钛矿优先垂直基底生长,为突破低效率瓶颈提供了可能。此外,以三维钙钛矿为基础,以有机胺为添加剂,制得的二维和三维混合的钙钛矿结构,也可以实现器件效率和稳定性的双提升。本文归纳了低维钙钛矿光伏器件的研究进展,分别对低维钙钛矿的分子结构、插入的有机胺的选择、钙钛矿薄膜的制备方法等进行介绍,分析了低维钙钛矿太阳能电池面临的问题并展望其前景,以期为制备稳定和环境友好的新型钙钛矿太阳能电池提供参考。     

In Situ Investigation of Reversible Exsolution/Dissolution of CoFe Alloy Nanoparticles in a Co-Doped Sr2Fe1.5Mo0.5O6−δ Cathode for CO2 Electrolysis

Reversible exsolution and dissolution of metal nanoparticles in perovskite has been investigated as an efficient strategy to improve CO₂ electrolysis performance. However, fundamental understanding with regard to the reversible exsolution and dissolution of metal nanoparticles in perovskite is still scarce. Herein, in situ exsolution and dissolution of CoFe alloy nanoparticles in Co-doped Sr₂Fe_1.5Mo_0.5O_6–δ (SFMC) revealed by in situ X-ray diffraction, scanning transmission electron microscopy, environmental scanning electron microscopy, and density functional theory calculations are reported. Under a reducing atmosphere, facile exsolution of Co promotes reduction of the Fe cation to generate CoFe alloy nanoparticles in SFMC, accompanied by structure transformation from double perovskite to layered perovskite at 800 °C. Under an oxidizing atmosphere, spherical CoFe alloy nanoparticles are first oxidized to flat CoFeO_x nanosheets, and then dissolved into the bulk with structure evolution from layered perovskite back to double perovskite. Electrochemically, CO₂ electrolysis performance can be retrieved during 12 redox cycles due to the regenerative ability of the CoFe alloy nanoparticles. The anchoring of the CoFe alloy nanoparticles in SFMC perovskite via reduction shows enhanced CO₂ electrolysis performance and stability compared with the parent SFMC perovskite.     

A-位和B-位共掺的Bi4Ti3O12陶瓷的结构及其铁电性能

采用固相烧结法制备了Bi3.55Nd0.45Ti3-xNbxO12(x=0、0.02、0.05、0.08、0.15)系层状钙钛矿结构无铅铁电陶瓷。通过X射线衍射仪(XRD)可以看出陶瓷样品为铋层状钙钛矿结构,并无杂相生成。随着Nb的含量增多,其衍射峰向低角度移动。从扫描电子显微镜(SEM)可以看出陶瓷晶粒为片状。利用阻抗分析仪LCR(HP4284A)测试了陶瓷的介电性能,研究表明AB位共掺钛酸铋陶瓷的居里温度在275℃左右,而Bi4Ti3O12的居里点是675℃,前者比后者下降了400℃。在利用铁电综合测试系统对铁电性能的研究过程中发现,与x=0.05相比,x=0.15的矫顽场(Ec)和剩余极化强度(2Pr)分别减小了5kV/cm和2μC/cm2。     

Combining Efficiency and Stability in Mixed Tin–Lead Perovskite Solar Cells by Capping Grains with an Ultrathin 2D Layer

The development of narrow-bandgap (E_g ≈ 1.2 eV) mixed tin–lead (Sn–Pb) halide perovskites enables all-perovskite tandem solar cells. Whereas pure-lead halide perovskite solar cells (PSCs) have advanced simultaneously in efficiency and stability, achieving this crucial combination remains a challenge in Sn–Pb PSCs. Here, Sn–Pb perovskite grains are anchored with ultrathin layered perovskites to overcome the efficiency-stability tradeoff. Defect passivation is achieved both on the perovskite film surface and at grain boundaries, an approach implemented by directly introducing phenethylammonium ligands in the antisolvent. This improves device operational stability and also avoids the excess formation of layered perovskites that would otherwise hinder charge transport. Sn–Pb PSCs with fill factors of 79% and a certified power conversion efficiency (PCE) of 18.95% are reported—among the highest for Sn–Pb PSCs. Using this approach, a 200-fold enhancement in device operating lifetime is achieved relative to the nonpassivated Sn–Pb PSCs under full AM1.5G illumination, and a 200 h diurnal operating time without efficiency drop is achieved under filtered AM1.5G illumination.     

Perovskites with Enriched Oxygen Vacancies as a Family of Electrocatalysts for Efficient Nitrate Reduction to Ammonia

Electrochemical nitrate reduction to ammonia (NRA) provides an efficient, sustainable approach to convert the nitrate pollutants into value-added products, which is regarded as a promising alternative to the industrial Haber–Bosch process. Recent studies have shown that oxygen vacancies of oxide catalysts can adjust the adsorption energies of intermediates and affect their catalytic performance. Compared with other metal oxides, perovskite oxides can allow their metal cations to exist in abnormal or mixed valence states, thereby resulting in enriched oxygen vacancies in their crystal structures. Here, the catalytic activities of perovskite oxides toward NRA catalysis with respect to the amount of oxygen vacancies are explored, where four perovskite oxides with different crystal structures (including cubic LaCrO₃, orthorhombic LaMnO₃ and LaFeO₃, hexagonal LaCoO₃) are chosen and investigated. By combining X-ray photoelectron spectroscopy, electron paramagnetic resonance spectroscopy and electrochemical measurements, it is found that the amount of oxygen vacancies in these perovskite oxides surprisingly follow the same order as their activities toward NRA catalysis (LaCrO₃ < LaMnO₃ < LaFeO₃ < LaCoO₃). Further theoretical studies reveal that the existence of oxygen vacancies in LaCoO₃ perovskite can decrease the energy barriers for reduction of *HNO₃ to *NO₂, leading to its superior NRA performance.     

MLnBO_4陶瓷中K_2NiF_4型层状钙钛矿结构的稳定性

通过固相反应法制备了MLnBO_4(M=Ba,Sr,Ca;Ln=La,Nd,Sm,Y;B=(Zn0.5Ti0.5),(Mg_(0.5)Ti_(0.5)))陶瓷粉末,使用X射线衍射仪(XRD)分析其相组成,并结合文献中B位为Ga和Al时的结果,探讨了MLnBO_4中K_2NiF_4型层状钙钛矿结构的稳定性。当M~(2+)和B~(3+)固定时,K_2NiF_4型结构的稳定性随钙钛矿层许容因子t偏离1程度的增加而降低;但当M~(2+)或B~(3+)改变时,两者之间并无直接联系。而考虑M~(2+)、Ln~(3+)、B~(3+)离子半径的对比时,则发现K_2NiF_4型结构均出现在以r(M~(2+))/r(Ln~(3+))=1.1、r(Ln~(3+))/r(B~(3+))=2为中心的一定范围内。因此,用M~(2+)、Ln~(3+)、B~(3+)离子半径的对比衡量MLnBO_4中K_2NiF_4型层状钙钛矿结构的稳定性远较用钙钛矿层的许容因子更可靠,这对于相关材料的设计和开发具有重要意义。     

具有2D-EDAPbI4薄覆盖层的环境稳定的FAPbI3基钙钛矿太阳能电池（英文）

二维(2D)卤化铅钙钛矿材料是钙钛矿太阳能电池(PSC)中最有前途的吸光材料之一,具有优异的稳定性和缺陷钝化作用.然而,这些稳定的二维PSC的转换效率仍远远落后于三维钙钛矿电池.在本文中我们通过原位生长的方法将2D EDAPbI4层成功制备在3D FAPbI3层表面。这种合理设计的2D-3D钙钛矿薄膜分层结构可以明显提高电池的效率.另外,由于EDAPbI4层的高抗湿性和抑制迁移, 2D-3D电池器件显示出明显增强的长期稳定性,在200 h内一直保持初始转换效率,甚至在500 h后仍能保持其初始转化效率的90%.     

Perovskite Materials for Light‐Emitting Diodes and Lasers

Organic–inorganic hybrid perovskites have cemented their position as an exceptional class of optoelectronic materials thanks to record photovoltaic efficiencies of 22.1%, as well as promising demonstrations of light‐emitting diodes, lasers, and light‐emitting transistors. Perovskite materials with photoluminescence quantum yields close to 100% and perovskite light‐emitting diodes with external quantum efficiencies of 8% and current efficiencies of 43 cd A^?1 have been achieved. Although perovskite light‐emitting devices are yet to become industrially relevant, in merely two years these devices have achieved the brightness and efficiencies that organic light‐emitting diodes accomplished in two decades. Further advances will rely decisively on the multitude of compositional, structural variants that enable the formation of lower‐dimensionality layered and three‐dimensional perovskites, nanostructures, charge‐transport materials, and device processing with architectural innovations. Here, the rapid advancements in perovskite light‐emitting devices and lasers are reviewed. The key challenges in materials development, device fabrication, operational stability are addressed, and an outlook is presented that will address market viability of perovskite light‐emitting devices.     

高稳定性(EDA)(FA)2[Pb3I10]层状钙钛矿薄膜的制备与表征

为了提高钙钛矿太阳能电池在潮湿环境中的稳定性, 采用一步法, 通过在DMF中混合(EDA)I₂、(FA)I和PbI₂, 将乙二胺离子引入钙钛矿晶格, 成功制备了一种具有较高稳定性的二维片层状的钙钛矿结构薄膜。通过原位掠入射X射线衍射(GIXRD)、X射线衍射(XRD)、扫描电子显微镜(SEM)、紫外-可见吸收光谱(UV-Vis)和原子力显微镜(AFM)等方法检测分析(EDA)(FA)₂[Pb₃I₁₀]在低湿度及高湿度环境下的结构、形貌以及光学性能变化。结果表明: 制备的 (EDA)(FA)₂[Pb₃I₁₀]薄膜在相同湿度环境下比当前广泛应用于钙钛矿太阳能电池的甲胺铅碘薄膜(CH₃NH₃PbI₃)稳定性更高; 薄膜的光学带隙约为1.67 eV, 与太阳能电池最佳带隙比较接近。另外, (EDA)(FA)₂[Pb₃I₁₀]薄膜在可见光范围吸光性能较好; 薄膜的粗糙度很小, 适合制备太阳能电池, 而且, 成本较硅基太阳能电池低廉, 在分子水平较CH₃NH₃PbI₃的可调谐性更大, 使钙钛矿太阳能电池在未来大面积应用成为可能。