过渡金属掺杂的双钙钛矿Ba2InNbO6的光催化分解水性能研究

双钙钛矿材料由于其丰富的化学组成及晶体结构被认为是一类优良的光催化材料,但大多数双钙钛矿氧化物仅表现出紫外光催化活性。因此,本文通过过渡金属离子Fe、Cr、Ni等掺杂调控双钙钛矿化合物Ba2InNbO6的能带结构,期望实现高效的可见光催化活性,并研究掺杂元素对晶体结构、微观形貌、表面状态等物化性质的影响。结果表明,过渡金属能够成功地引入到双钙钛矿的Ba2InNbO6的In位点,并能拓宽材料的可见光吸收范围。此外,过渡金属引入晶胞发生收缩,颗粒尺寸增大,表面亲水性也得到了极大的改善。与Ba2InNbO6相比,过渡金属掺杂的样品光催化析氢活性得到了极大的改善。其中,Ba2In0.9Fe0.1NbO6在全范围照射(λ≥250 nm)下的析氢量最高,达到了15.8μmol,并且在可见光(λ≥420 nm)照射下的析氢速率为2.71μmol/h,其对应的表观量子效率为0.016%。     

环境友好型无铅卤化物钙钛矿太阳能电池研究进展

ABX₃(A为甲胺、甲脒等有机离子或铯离子,B为铅或锡等金属离子,X为溴、碘等卤化物离子)卤化物钙钛矿材料具有优异的光电特性,是当前太阳能电池研究的前沿和热点之一。然而,这类太阳能电池普遍面临含毒性元素铅和稳定性差等问题,极大地阻碍了钙钛矿太阳能电池商业化应用进程。因此,发展新型高效无铅钙钛矿太阳能电池势在必行。本文评述了环境友好型无铅卤化物钙钛矿太阳能电池的最新研究动态和进展,探讨了该类太阳能电池的制备、性能及其稳定性等问题,展望了其未来发展趋势。     

钙钛矿材料光催化还原CO2综述

利用半导体材料光催化还原CO2合成可燃物是目前解决能源危机和缓解温室效应的理想途径.本文对几种钙钛矿型材料,包括纯无机卤化物钙钛矿材料、金属有机钙钛矿材料、氧化物型钙钛矿材料和复合型钙钛矿材料在光催化还原CO2领域的应用进行了简单的归纳与总结.     

金属有机框架(MOFs)基光催化剂的设计及其在太阳能燃料生产和污染物降解领域的研究进展

金属有机骨架(MOFs)具有较高的比表面积,丰富的金属/有机物种,较大的孔体积以及结构和成分可调节的特性,因此在太阳能燃料生产和污染物的光降解领域具有广泛的应用.根据其结构特点,研究者们主要从有机配体和孔道结构两方面对MOFs进行调控:(1)对有机配体进行修饰,如将杂原子、羟基、卤素原子、金属离子、生物大分子等引入MO...     

无铅卤系钙钛矿纳米晶:新一代光催化材料

由于TiO₂光催化材料具有反应速度快、稳定性好、不产生二次污染等优点,常被应用于污染物降解、CO₂还原、制氢等领域,然而TiO₂可见光利用率低,限制了其进一步广泛应用。近年来,无铅卤系钙钛矿纳米晶由于其带隙可调、可见光吸收能力强等优势在光催化领域显示出巨大的潜力。相关研究表明:无铅卤系钙钛矿纳米晶可成功应用于CO₂还原、有机污染物降解等领域,效果显著。基于此,本文首先阐述了无铅卤系钙钛矿纳米晶的制备方法,并系统地总结了其在CO₂还原、制氢、污染物降解、NO去除等领域的应用研究进展,最后就现阶段无铅卤系钙钛矿纳米晶光催化材料研究中存在的问题及今后的研究方向进行了分析和展望。     

金属卤化物钙钛矿光电材料和器件

2009年ABX₃钙钛矿晶型的甲胺铅卤CH₃NH₃PbX₃(X=I、Br、Cl)钙钛矿材料首次应用于太阳能电池,但初始报道效率低、稳定性差。2012年后,可溶液法制备的钙钛矿太阳能电池凭借其吸光系数高、激子结合能低等优点,迅速表现出低成本和高效率的突出优势,并在光电器件等交叉领域具有很强的应用潜力。因此,钙钛矿太阳能电池被Science杂志评为2013年度国际十大科技进展,是化学和材料领域特别是光伏领域新兴的变革性技术之一。钙钛矿太阳能电池材料与器件的发展一直面临大面积、高效率、稳定性和环境友好性等挑战,对应的是钙钛矿晶体可控生长、缺陷钝化、器件优化材料稳定性和铅毒性等科学问题。     

金属有机框架(MOFs)基光催化剂的设计及其在太阳能燃料生产和污染物降解领域的研究进展（英文）

金属有机骨架(MOFs)具有较高的比表面积,丰富的金属/有机物种,较大的孔体积以及结构和成分可调节的特性,因此在太阳能燃料生产和污染物的光降解领域具有广泛的应用.根据其结构特点,研究者们主要从有机配体和孔道结构两方面对MOFs进行调控:(1)对有机配体进行修饰,如将杂原子、羟基、卤素原子、金属离子、生物大分子等引入MOFs结构;(2)将无机纳米粒子引入MOFs孔道内,如将贵金属、金属氧化物、多金属氧酸盐等纳米粒子封装在MOFs的孔道内.这些策略可有效增强MOFs的导电性、稳定性等,并进一步提高MOFs基催化剂的光催化性能.本文首先概述了四种经典MOFs类型,即UiO, ZIF, MIL和PCN系列的结构特点和催化性能.其次,总结了在设计MOFs基光催化材料过程中,根据不同类型MOFs特点着重考虑的五方面因素,即稳定性、能带结构、吸附作用、选择性和电导性.再次,讨论了提高MOFs基光催化剂活性的策略,如助催化剂修饰、构建异质结、配体或金属中心修饰和缺陷工程.最后,总结了MOFs基光催化材料在催化还原CO₂、分解水制氢和降解有机污染物反应中的应用进展及影响其催化性能的...     

金属卤化物钙钛矿纳米晶高效发光二极管的制备与器件性能优化

金属卤化物钙钛矿作为一类新型的离子型直接带隙半导体材料在电致发光二极管(LED)中有着重要应用前景. 但实现其应用的前提在于金属卤化物钙钛矿材料需要保持高的发光效率和好的稳定性. 为了提高金属卤化物钙钛矿作为LED发光层的激子结合效率, 从而提升其发光效率, 设计和合成金属卤化物钙钛矿纳米晶材料是一个有效途径. 目前, 基于纳米晶材料设计的金属卤化物钙钛矿LED在绿光和红光(包括近红外光)范围已经展现了高的发光亮度和外量子效率(EQE), 其中最高EQE已经超过了20%, 但其稳定性仍无法满足器件应用的要求. 此外, 更值得关注且更重要的是, 蓝光钙钛矿LED的发光亮度和EQE目前仍然不高. 如何制备高效、 稳定的金属卤化物钙钛矿纳米晶LED, 特别是蓝光LED, 是一个具有重大应用前景且具有挑战性的课题. 本文重点介绍了金属卤化物钙钛矿纳米发光层的结构设计和合成方法及金属卤化物钙钛矿LED的研究进展, 分析了金属卤化物钙钛矿LED不稳定的原因, 并对金属卤化物钙钛矿LED研究面临的挑战和未来发展方向进行了总结与展望.     

皂土固载金属酞菁用于光催化还原CO2的反应

制备了三种皂土固载金属酞菁(ZnPc,CoPc,NiPc),研究了它们在可见光照射下,对CO2还原反应的催化作用.MPc/皂土作为P-型半导体,光照下可产生电子转移得到MPc. .研究结果表明,皂土固载金属酞菁比未固载金属酞菁具有更好的催化性能和重复使用性能,而且与酞菁中心配位的金属对其催化性能有影响,本实验中ZnPc/皂土较好,其负载量为1.0%.     

Recent Advances and Future Perspectives of Lead-Free Halide Perovskites for Photocatalytic CO2 Reduction

It is still challenging to design and develop the state-of-the-art photocatalysts toward CO₂ photoreduction. Enormous researchers have focused on the halide perovskites in the photocatalytic field for CO₂ photoreduction, due to their excellent optical and physical properties. The toxicity of lead-based halide perovskites prevents their large-scale applications in photocatalytic fields. In consequence, lead-free halide perovskites (LFHPs) without the toxicity become the promising alternatives in the photocatalytic application for CO₂ photoreduction. In recent years, the rapid advances of LFHPs have offer new chances for the photocatalytic CO₂ reduction of LFHPs. In this review, we summarize not only the structures and properties of A₂BX₆, A₂B(I)B(III)X₆, and A₃B₂X₉-type LFHPs but also their recent progresses on the photocatalytic CO₂ reduction. Furthermore, we also point out the opportunities and perspectives to research LFHPs photocatalysts for CO₂ photoreduction in the future.     

Bismuth-Based Halide Perovskites for Photocatalytic H2 Evolution Application

Metal halide perovskites (MHPs), in particular lead-based perovskites, have earned recognized fame in several fields for their outstanding optoelectronic properties, including direct generation of free charge carriers, optimal ambipolar charge carrier transport properties, high absorption coefficient, point-defect tolerance, and compositional versatility. Nowadays, this class of materials represents a real and promising alternative to silicon for photovoltaic technologies. This worthy success led to a growing interest in the exploration of MHPs in other hot research fields, such as solar-driven photocatalytic water splitting towards hydrogen production. Nevertheless, many of these perovskites show air and moisture instability problems that considerably hinder their practical application for photocatalytic water splitting. Moreover, if chemical instability is a problem that can be in part mitigated by the optimization of the chemical composition and crystal structure, the presence of lead represents a real problem for the practical application of MHPs in commercial devices due to environmental and healthcare issues. To successfully overcome these problems, lead-free metal halide perovskites (LFMHPs) have gained increasing interest thanks to their optoelectronic properties, comparable to lead-based materials, and their more eco-friendly nature. Among all the lead-free perovskite alternatives, this mini-review considers bismuth-based perovskites and perovskite derivatives with a specific focus on solar-driven photocatalysis application for H₂ evolution. Special attention is dedicated to the structure and composition of the different materials and to the advantage of heterojunction engineering and the relative impact on the photocatalytic process.     

Photoredox Organic Synthesis Employing Heterogeneous Photocatalysts with Emphasis on Halide Perovskite

Lately, heterogeneous semiconductor materials have been explored as an emerging type of efficient photocatalyst for photoredox organic synthesis. Among these semiconductors, lead halide perovskite materials demonstrate unique properties towards excellent charge separation and charge transfer, extremely long charge carrier migration, high efficiency in visible light absorption, and long excited states lifetimes, etc., as proved in ground-breaking solar cell applications, garnering necessary merits for an efficient catalytic system for photoredox organic reactions. Here, the latest progress in heterogeneous semiconductor materials towards this endeavor is examined, with particular emphasis on lead halide perovskite nanocrystals (NCs) in photocatalytic organic synthesis.     

A Review on Cs-Based Pb-Free Double Halide Perovskites: From Theoretical and Experimental Studies to Doping and Applications

Despite the progressive enhancement in the flexibility of Pb-based perovskites for optoelectronic applications, regrettably, they are facing two main challenges; (1) instability, which originates from using organic components in the perovskite structure, and (2) toxicity due to Pb. Therefore, new, stable non-toxic perovskite materials are demanded to overcome these drawbacks. The research community has been working on a wide variety of Pb-free perovskites with different molecular formulas and dimensionality. A variety of Pb-free halide double perovskites have been widely explored by different research groups in search for stable, non-toxic double perovskite material. Especially, Cs-based Pb-free halide double perovskite has been in focus recently. Herein, we present a review of theoretical and experimental research on Cs-based Pb-free double halide perovskites of structural formulas Cs₂M⁺M³⁺X6 (M⁺ = Ag⁺, Na⁺, In⁺ etc.; M³⁺= Bi³⁺, In³⁺, Sb³⁺; X = Cl⁻, Br⁻, I¯) and Cs₂M⁴⁺X₆ (M⁴⁺ = Ti⁴⁺, Sn⁴⁺, Au⁴⁺ etc.). We also present the challenges faced by these perovskite compounds and their current applications especially in photovoltaics alongside the effect of metal dopants on their performance.     

Two-Dimensional Halide Perovskites: Approaches to Improve Optoelectronic Properties

Three-dimensional (3D) halide perovskites (HPs) are in the spotlight of materials science research due to their excellent photonic and electronic properties suitable for functional device applications. However, the intrinsic instability of these materials stands as a hurdle in the way to their commercialization. Recently, two-dimensional (2D) HPs have emerged as an alternative to 3D perovskites, thanks to their excellent stability and tunable optoelectronic properties. Unlike 3D HPs, a library of 2D perovskites could be prepared by utilizing the unlimited number of organic cations since their formation is not within the boundary of the Goldschmidt tolerance factor. These materials have already proved their potential for applications such as solar cells, light-emitting diodes, transistors, photodetectors, photocatalysis, etc. However, poor charge carrier separation and transport efficiencies of 2D HPs are the bottlenecks resulting in inferior device performances compared to their 3D analogs. This minireview focuses on how to address these issues through the adoption of different strategies and improve the optoelectronic properties of 2D perovskites.     

DFT Simulations as Valuable Tool to Support NMR Characterization of Halide Perovskites: the Case of Pure and Mixed Halide Perovskites

Solid state NMR spectroscopy is swiftly emerging as useful tool to characterize the structure, composition and dynamic properties of lead halide perovskites. On the other hand, interpretation of solid state NMR signatures is often challenging, because of the potential presence of many overlapping signals in small range of chemical shifts, hence complicating the extraction of detailed structural features. Here, we demonstrate the reliability of periodic Density Functional Theory in providing theoretical support for the NMR characterization of halide perovskite compounds, considering nuclei with spin I=1/2. For light ¹H and ¹³C nuclei, we predict NMR chemical shifts in good agreement with experiment, further highlighting the effects of motional narrowing. Accurate prediction of the NMR response of ²⁰⁷Pb nuclei is comparably more challenging, but we successfully reproduce the downshift in frequency when changing the halide composition from pure iodine to pure bromine. Furthermore, we confirm NMR as ideal tool to study mixed halide perovskite compounds, currently at the limelight for tandem solar cells and color-tunable light emission.     

Solubility of Hybrid Halide Perovskites in DMF and DMSO

Solution methods remain the most popular means for the fabrication of hybrid halide perovskites. However, the solubility of hybrid perovskites has not yet been quantitively investigated. In this study, we present accurate solubility data for MAPbI₃, FAPbI₃, MAPbBr₃ and FAPbBr₃ in the two most widely used solvents, DMF and DMSO, and demonstrate huge differences in the solubility behavior depending on the solution compositions. By analyzing the donor numbers of the solvents and halide anions, we rationalize the differences in the solubility behavior of hybrid perovskites with various compositions, in order to take a step forward in the search for better processing conditions of hybrid perovskites for solar cells and optoelectronics.     

Glycine-Functionalized CsPbBr3 Nanocrystals for Efficient Visible-Light Photocatalysis of CO2 Reduction

Capping ligands are indispensable for the preparation of metal-halide-perovskite (MHP) nanocrystals (NCs) with good stability; however, the long alkyl-chain capping ligands in conventional MHP NCs will be unfavorable for CO₂ adsorption and hinder the efficient carrier separation on the surface of MHP NCs, leading to inferior catalytic activity in artificial photosynthesis. Herein, CsPbBr₃ nanocrystals with short-chain glycine as ligand are constructed through a facile ligand-exchange strategy. Owing to the reduced hindrance of glycine and the presence of the amine group in glycine, the photogenerated carrier separation and CO₂ uptake capacity are noticeably improved without compromising the stability of the MHP NCs. The CsPbBr₃ nanocrystals with glycine ligands exhibit a significantly increased yield of 27.7 μmol g⁻¹ h⁻¹ for photocatalytic CO₂-to-CO conversion without any organic sacrificial reagents, which is over five times higher than that of control CsPbBr₃ NCs with conventional long alkyl-chain capping ligands.     

The Role of Surface Termination in Halide Perovskites for Efficient Photocatalytic Synthesis

Halide perovskites have received attention in the field of photocatalysis owing to their excellent optoelectronic properties. However, the semiconductor properties of halide perovskite surfaces and the influence on photocatalytic performance have not been systematically clarified. Now, the conversion of triose (such as 1,3‐dihydroxyacetone (DHA)) is employed as a model reaction to explore the surface termination of MAPbI₃. By rational design of the surface termination for MAPbI₃, the production rate of butyl lactate is substantially improved to 7719 μg g^?1 cat. h^?1 under visible‐light illumination. The MAI‐terminated MAPbI₃ surface governs the photocatalytic performance. Specially, MAI‐terminated surface is susceptible to iodide oxidation, which thus promotes the exposure of Pb^II as active sites for this photocatalysis process. Moreover, MAI‐termination induces a p‐doping effect near the surface for MAPbI₃, which facilitates carrier transport and thus photosynthesis.