MOF-Mediated Synthesis of Supported Fe-Doped Pd Nanoparticles under Mild Conditions for Magnetically Recoverable Catalysis**

Metal–organic framework (MOF)-driven synthesis is considered as a promising alternative for the development of new catalytic materials with well-designed active sites. This synthetic approach is used here to gradually transform a new bimetallic MOF, with Pd and Fe as the metal components, by the in situ generation of aniline under mild conditions. This methodology results in a compositionally homogeneous nanocomposite formed by Fe-doped Pd nanoparticles that, in turn, are supported on iron oxide-doped carbon. The nanocomposite has been fully characterized by several techniques such as IR and Raman spectroscopy, TEM, XPS, and XAS. The performance of this nanocomposite as an heterogeneous catalyst for hydrogenation of nitroarenes and nitrobenzene coupling with benzaldehyde has been evaluated, proving it to be an efficient and reusable catalyst.     

胶质碳球为模板制备NiO空心球

以胶质碳球为模板、六亚甲基四胺为沉淀剂,在乙醇中溶剂热反应,再经500℃煅烧6 h制备了NiO空心球。通过X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、傅里叶变换红外光谱(FTIR)和低温氮吸附-脱附,对NiO的结构和形貌进行了表征。结果表明溶剂热反应时间是制备完整NiO空心球的关键因素,溶剂热反应12 h,再经空气中煅烧,可制得形貌均一的NiO空心球。所得产物是由NiO纳米粒子组装而成的具有多孔结构的空心球。同时,本文对NiO空心球结构的形成过程和可能机理进行了分析和讨论。     

无机中空球的分类、合成方法及应用

中空球是壳层结构材料的一个重要分支。与实心球相比较,中空球具有更多特殊和优异的物理及化学性质,例如具有较小的密度、较大的比表面积以及较好的稳定性和表面渗透性,其中无机中空球较有机中空球还具有耐高温、抗老化等优点。因此,近些年来无机中空球备受人们的关注,广泛应用于催化、电池、医药等众多领域。本文结合本课题组在无机氧化物中空球领域的研究和前人的工作,总结了近5年来制备无机中空球的研究进展。将无机中空球的壳层材料分为五大类,包括:无机氧化物、硫化物及硒化物、金属单质、复合物和其他无机材料。将制备方法分成四大类:硬模板法、软模板法、牺牲模板法和无模板法,对每一大类又进一步细分,并且指出了各种方法的优缺点。同时归纳了无机中空球几个重要的应用领域,如药物、电池、气体传感器和光催化领域。最后在此基础上简要展望了无机中空球的研究前景。     

Nitrogen and Oxygen Co-Doping Assisted Synthesis of Highly Dispersed Pd Nanoparticles on Hollow Carbon Spheres as Efficient Electrocatalysts for Oxygen Reduction Reaction

Electrochemical reduction of O₂ (oxygen reduction reaction; ORR) provides an opportunity to achieve the commercial application of clean energy, but it remains challenging, so the rational design of inexpensive and efficient electrocatalysts is required. Palladium-based electrocatalysts have emerged as a class of the most promising candidates for the ORR, which could accelerate O₂ adsorption, dissociation, and electron transfer. However, the metal Pd atoms tend to aggregate into nanoparticles, driven by the tendency of the metal surface free energy to decrease, which significantly reduces the atom utilization efficiency and the catalytic performance. Herein, a facile double solvent impregnation method is developed for the synthesis of highly dispersed Pd nanoparticles supported on hollow carbon spheres (Pd-HCS), which could act as efficient electrocatalysts for the ORR in basic solution. Systematic investigation reveals that the nitrogen-containing and oxygen-containing functional groups (especially −COOH groups) are essential for achieving the homogenous dispersion of Pd nanoparticles. Significantly, the optimized Pd-HCS electrocatalyst with homogeneously dispersed Pd nanoparticles and Pd−N sites delivers high electrocatalytic activity for the ORR and excellent stability, without significant decay in onset potential and half-potential and good resistance to methanol crossover. This work offers a new route for the rational design of efficient ORR electrocatalysts toward advanced materials and emerging applications.     

聚氯乙烯多乙烯多胺树脂的相转移催化作用

聚氯乙烯多乙烯多胺树脂可作为酯水解、氧取代(醚和酯的合成)、卤素取代(丁基碘和硫氰酸卞酯的合成)和缩合反应(卞叉丙酮的合成)的催化剂,效果良好。它是一种新型的高分子相转移催化剂。     

Pd/MIL-101的制备及非均相催化吲哚C-H活化

水热合成MIL-101,过量浸渍法吸附Pd(OAc)_2,原位还原Pd~(2+)制得Pd/MIL-101催化剂.采用XRD、XPS、SEM、ICP、HRTEM和N_2吸/脱附实验对其结构进行表征,催化剂Pd纳米粒子尺寸在1.5~2.5 nm之间,含量为1.5%.催化实验表明,Pd/MIL-101能高效催化吲哚C_2位芳基化,对于活性较差的溴代芳烃,也能得到中等以上的收率,催化剂循环5次后仍能保持较高的反应活性,发展了吲哚C_2位衍生物的简单、高效的合成方法.     

Recent Advances in Covalent Organic Frameworks for Catalysis

Covalent organic frameworks (COFs) as an emerging type of crystalline porous materials, have obtained considerable attention recently. They have exhibited diverse structure and attractive performance in various catalytic reactions. It is highly expected to have a systematic and comprehensive review summing up COFs‐derived catalysts in homogeneous and heterogeneous catalysis, which is favorable to the judicious design of an efficient catalyst for targeted reaction. Herein, we focus on summarizing recent and significant developments in COFs materials, with an emphasis on both the synthetic strategies and targeted functionalization, and categorize it in accordance with the different types of catalytic reactions. Their potential catalysis applications are reviewed thoroughly. Moreover, a personal view about the future development of COFs catalysts with respect to the large‐scale production is also discussed.     

Template Polymerization Based on Stober Method： an improved Method for Fabrication of Hollow Polysiloxane Spheres

Composite materials derived from coating or templating colloidal particles often exhibit unique properties and therefore has been intensively pursued1-3. For example, hollow spheres produced by colloidal templating are of interest in diverse applications,…     

Design of Photoactive Covalent Organic Frameworks as Heterogeneous Catalyst for Preparation of Thiophosphinates from Phosphine Oxides and Thiols

Two new covalent organic frameworks (COFs) were synthesized from 4,4′,4′′,4′′′-(pyrene-1,3,6,8-tetrayl)tetraaniline and 2,5-dimethoxyterephthalaldehyde (Py-DMTA-COF) or 2′,5′-dimethoxy-[1,1′:4′,1′′-terphenyl]-4,4′′-dicarbaldehyde (Py-DMTPDA-COF) under solvothermal conditions. These two COFs were further facilely developed as efficient photocatalytic platforms for the synthesis of thiophosphinates. Py-DMTA-COF exhibited better photocatalytic activity, broad substrate applicability, and excellent recycling capacity for the preparation of thiophosphinates from P(O)H compounds and thiols compared to Py-DMTPDA-COF. This methodology was further extended to the seamless gram-scale production of target phosphorothioate derivatives. The results demonstrate that COFs can provide a robust platform for developing metal-free, base-free, highly efficient, and reusable heterogeneous photocatalysts for organic transformations.     

Zr-MOF-808 as Catalyst for Amide Esterification

In this work, zirconium-based metal–organic framework Zr-MOF-808-P has been found to be an efficient and versatile catalyst for amide esterification. Comparing with previously reported homogeneous and heterogeneous catalysts, Zr-MOF-808-P can promote the reaction for a wide range of primary, secondary and tertiary amides with n-butanol as nucleophilic agent. Different alcohols have been employed in amide esterification with quantitative yields. Moreover, the catalyst acts as a heterogeneous catalyst and could be reused for at least five consecutive cycles. The amide esterification mechanism has been studied on the Zr-MOF-808 at molecular level by in situ FTIR spectroscopic technique and kinetic study.     

Homochiral Covalent Organic Frameworks for Asymmetric Catalysis

Owing to their permanent porosity, highly ordered and extended structure, good chemical stability, and tunability, covalent organic frameworks (COFs) have emerged as a new type of organic materials that can offer various applications in different fields. Benefiting from the huge database of organic reactions, the required functionality of COFs can be readily achieved by modification of the corresponding organic functional groups on either polymerizable monomers or established COF frameworks. This striking feature allows homochiral covalent organic frameworks (HCCOFs) to be reasonably designed and synthesized, as well as their use as a unique platform to fabricate asymmetric catalysts. This contribution provides an overview of new progress in HCCOF-based asymmetric catalysis, including design, synthesis, and their application in asymmetric organic synthesis. Moreover, major challenges and developing trends in this field are also discussed. It is anticipated that this review article will provide some new insights into HCCOFs for heterogeneous asymmetric catalysis and help to encourage further contributions in this young but promising field.     

Formation of Triple‐Shelled Molybdenum–Polydopamine Hollow Spheres and Their Conversion into MoO2/Carbon Composite Hollow Spheres for Lithium‐Ion Batteries

Unique triple‐shelled Mo‐polydopamine (Mo‐PDA) hollow spheres are synthesized through a facile solvothermal process. A sequential self‐templating mechanism for the multi‐shell formation is proposed, and the number of shells can be adjusted by tuning the size of the Mo‐glycerate templates. These triple‐shelled Mo‐PDA hollow spheres can be converted to triple‐shelled MoO₂/carbon composite hollow spheres by thermal treatment. Owing to the unique multi‐shells and hollow interior, the as‐prepared MoO₂/carbon composite hollow spheres exhibit appealing performance as an anode material for lithium‐ion batteries, delivering a high capacity of ca. 580 mAh g^?1 at 0.5 A g^?1 with good rate capability and long cycle life.     

Water‐dispersible Hollow Microporous Organic Network Spheres as Substrate for Electroless Deposition of Ultrafine Pd Nanoparticles with High Catalytic Activity and Recyclability

Microporous organic networks (MONs) have been considered as an ideal substrate to stabilize active metal nanoparticles. However, the development of highly water‐dispersible hollow MONs nanostructures which can serve as both the reducing agent and stabilizer is highly desirable but still challenging. Here we report a template‐assisted method to synthesize hollow microporous organic network (H‐MON) spheres using silica spheres as hard template and 1,3,5‐triethynylbenzene as the building blocks through a Glaser coupling reaction. The obtained water‐dispersible H‐MON spheres bearing sp‐ and sp²‐hybridized carbon atoms possess a highly conjugated electronic structure and show low reduction potential; thus, they can serve as a reducing agent and stabilizer for electroless deposition of highly dispersed Pd clusters to form a Pd/H‐MON spherical hollow nanocomposite. Benefitting from their high porosity, large surface area, and excellent solution dispersibility, the as‐prepared Pd/H‐MON hollow nanocomposite exhibits a high catalytic performance and recyclability toward the reduction of 4‐nitrophenol.     

Oxidation of Benzyl Alcohol Using Cobalt Oxide Supported Inside and Outside Hollow Carbon Spheres

Cobalt oxide nanoparticles (6 nm) supported both inside and outside of hollow carbon spheres (HCSs) were synthesized by using two different polymer templates. The oxidation of benzyl alcohol was used as a model reaction to evaluate the catalysts. PXRD studies indicated that the Co oxidation state varied for the different catalysts due to reduction of the Co by the carbon, and a metal oxidation step prior to the benzyl alcohol oxidation enhanced the catalytic activity. The metal loading influenced the catalytic efficiency, and the activity decreased with increasing metal loading, possibly due to pore filling effects. The catalysts showed similar activity and selectivity (to benzaldehyde) whether placed inside or outside the HCS (63 % selectivity at 50 % conversion). No poisoning was observed due to product build up in the HCS.     

Sonochemical Preparation of Hierarchical ZnO Hollow Spheres for Efficient Dye‐Sensitized Solar Cells

Hierarchical ZnO hollow spheres (400–500 nm in diameter) consisting of ZnO nanoparticles with a diameter of approximately 15 nm have been successfully prepared by a facile and rapid sonochemical process. The formation of hierarchical ZnO hollow spheres is attributed to the oriented attachment and subsequent Ostwald ripening process according to time‐dependent experiments. The as‐prepared ZnO hollow spheres are used as a photoanode in dye‐sensitized solar cells and exhibit a highly efficient power conversion efficiency of 4.33 %, with a short‐circuit current density of 9.56 mA cm^?2, an open‐circuit voltage of 730 mV, and a fill factor of 0.62 under AM 1.5 G one sun (100 mW cm^?2) illumination. Moreover, the photovoltaic performance (4.33 %) using the hierarchical ZnO hollow spheres is 38.8 % better than that of a ZnO nanoparticle photoelectrode (3.12 %), which is mainly attributed to the efficient light scattering for the former.     

纳米SnSe2空心球上乙酰胆碱酯酶的固定及辛硫磷传感器的构建

描述了一种将乙酰胆碱酯酶固定在SnSe2空心球上检测辛硫磷的简单方法,用水热法合成了SnSe2空心球,并用透射电镜对其表征.固定的乙酰胆碱酯酶能保持其生物学活性,催化乙酰胆碱为胆碱,胆碱被氧化产生可检测的信号.基于辛硫磷对乙酰胆碱酯酶活性有抑制作用这个机理,在理想条件下,这种传感器对辛硫磷检测的线性范围是0.008～56μg/mL,检测限为0.004μg/mL.这种新型的传感器有很好的稳定性和重现性.这项工作表明SnSe2空心球可以作为固定乙酰胆碱酯酶的理想载体并用于构建相应的传感器.     

一种制备单分散SiO2空心微球的新方法

在乙醇/氨水介质中, 分别以分散聚合和无皂乳液聚合方法制得的不同粒径聚苯乙烯(PS)微球为模板, 以正硅酸乙酯(TEOS)为前驱体, 通过控制介质中氨水的初始体积, 一步法制得了不同粒径的单分散SiO2空心微球. 整个过程无需添加其它溶剂溶解或高温煅烧的方法来除去模板微球. 对SiO2空心微球进行测试表征, 提出了SiO2空心微球的可能形成机制.     

Covalent Triazine Framework Nanoparticles via Size-Controllable Confinement Synthesis for Enhanced Visible-Light Photoredox Catalysis

For metal-free, organic conjugated polymer-based photocatalysts, synthesis of defined nanostructures is still highly challenging. Here, we report the formation of covalent triazine framework (CTF) nanoparticles via a size-controllable confined polymerization strategy. The uniform CTF nanoparticles exhibited significantly enhanced activity in the photocatalytic formation of dibenzofurans compared to the irregular bulk material. The optoelectronic properties of the nanometer-sized CTFs could be easily tuned by copolymerizing small amounts of benzothiadiazole into the conjugated molecular network. This optimization of electronic properties led to a further increase in observed photocatalytic efficiency, resulting in total an 18-fold enhancement compared to the bulk material. Full recyclability of the heterogeneous photocatalysts as well as catalytic activity in dehalogenation, hydroxylation and benzoimidazole formation reactions demonstrated the utility of the designed materials.     

Heat‐Treated Aerogel as a Catalyst for the Oxygen Reduction Reaction

Aerogels are fascinating materials that can be used for a wide range of applications, one of which is electrocatalysis of the important oxygen reduction reaction. In their inorganic form, aerogels can have ultrahigh catalytic site density, high surface area, and tunable physical properties and chemical structures—important features in heterogeneous catalysis. Herein, we report on the synthesis and electrocatalytic properties of an iron–porphyrin aerogel. 5,10,15,20‐(Tetra‐4‐aminophenyl)porphyrin (H₂TAPP) and Fe^II were used as building blocks of the aerogel, which was later heat‐treated at 600 °C to enhance electronic conductivity and catalytic activity, while preserving its macrostructure. The resulting material has a very high concentration of atomically dispersed catalytic sites (9.7×10²⁰ sites g^?1) capable of catalyzing the oxygen reduction reaction in alkaline solution (E_onset=0.92 V vs. RHE, TOF=0.25 e^? site^?1 s^?1 at 0.80 V vs. RHE).     

Outside‐In Recrystallization of ZnS–Cu1.8S Hollow Spheres with Interdispersed Lattices for Enhanced Visible Light Solar Hydrogen Generation

For the first time an earth‐abundant and nontoxic ZnS–Cu_1.8S hybrid photocatalyst has been engineered with well‐defined nanosheet hollow structures by a template‐engaged method. In contrast to conventional surface coupling and loading, the unique outside‐in recrystallization promotes co‐precipitation of ZnS and Cu_1.8S into homogeneous interdispersed lattices, hence forming a hybrid semiconductor with visible responsive photocatalytic activity. The as‐derived ZnS–Cu_1.8S semiconductor alloy is tailored into a hierarchical hollow structure to provide readily accessible porous shells and interior spaces for effective ion transfer/exchange. Notably, this synergistic morphology, interface and crystal lattice engineering, aim towards the design of novel nanocatalysts for various sustainable environmental and energy applications.