亚胺COFs在电催化领域的应用研究进展

亚胺共价有机框架材料(COFs)作为一种新兴的多孔晶体聚合物,具有规整的孔结构、高的比表面积、可调的抗衡离子、丰富的活性位点等.在燃料电池中,亚胺COFs对于制备高效电催化剂和促进能量转换至关重要.首先介绍了亚胺COFs基电催化剂的优势;然后综述了其作为电催化剂在还原CO2、析氧反应、析氢反应、氧还原反应等领域的应用;最后讨论了亚胺COFs高性能电催化剂当前的挑战和未来前景.     

金属有机骨架材料储存CO_2的研究进展

随着温室效应日益严重,研发高效捕获CO_2的新型材料对于缓解环境压力具有重要意义。金属有机骨架材料具有高比表面积、结构多样性和孔道可调控性等优点,尤其在储存CO_2方面展现出惊人潜质。简要介绍金属有机骨架材料及其延伸化合物——沸石咪唑酯骨架材料和共价有机骨架材料作为新型储存CO_2材料,在结构、储存CO_2性能和机理等方面的研究进展,并阐述了该类材料在研究过程中存在的不足与发展前景。     

共价有机骨架材料的制备及在环境领域的应用

共价有机框架(Covalent organic frameworks,COFs)材料是一类多孔的,由共价有机结构块组成的有机高分子材料。由于COFs材料优良的性能使其在环境领域具有广泛的应用。本文对COFs材料的合成、修饰以及COFs材料及其衍生物在环境修复领域的应用进行了总结,并针对目前COFs材料在环境修复领域的研究存在的问题及未来的研究方向进行了讨论和展望。     

共价有机骨架化合物(COFs)储氢材料研究进展

简要介绍了二维和三维COFs的结构,重点介绍了COFs作为储氢材料的研究现状和提高其储氢性能的改性方法,并对COFs在储氢方面存在的不足和未来的研究方向作出了总结与展望。     

The investigation of gold/zirconia as a photocatalyst for the direct synthesis of imines from alcohols and aniline

Au/ZrO₂ nanoparticles have been widely used as photocatalysts in various organic syntheses because of their localized surface plasmon resonance (LSPR) effects. In our work, Au/ZrO₂ has been synthesized by a solution method and it was used as a heterogeneous catalyst in the synthesis of imines from alcohols and aniline with irradiation by visible light. The reaction occurred in two steps: step 1 was the aerobic oxidation of the alcohols and step 2 was the nucleophilic addition of aniline. Dimethyl sulfoxide (DMSO) was used as a solvent in the reaction. The selectivity in the synthesis of imines over 3 wt% Au/ZrO₂ (with mean particle size of 5 nm) was high (over 90%) with irradiation by visible light at room temperature, and an obvious difference in the conversion was observed between the reactions with light irradiation and those without light. The intensity and wavelength of the light strongly affected the reaction. The Au/ZrO₂ could be used at least 5 times. A reaction mechanism was proposed based on the experimental results. The results indicate that the reaction of alcohols and aniline using Au/ZrO₂ as the photocatalyst can proceed under mild conditions. Furthermore, this process is environmentally friendly and green.     

Standing Carbon‐Supported Trace Levels of Metal Derived from Covalent Organic Framework for Electrocatalysis

Single atom catalysts (SACs) are receiving increasing interests due to their high theoretical catalytic efficiency and intriguing physiochemical properties. However, most of the synthetic methodologies involve high‐temperature treatment. This usually leads to limited control over the spatial distribution of metal sites and collapse of porous network that result in limited active site exposure. A strategy to construct SAC by using a covalent organic framework as the precursor is reported in this study. The as‐prepared catalyst is mainly composed of standing carbon layers with the presence of edge‐site hosted metal single atoms. Such structure configuration not only allows full site exposure but also endows the metal site with high intrinsic activity. With a trace amount of cobalt loading (0.17 wt%), the nanorice‐shaped catalyst displays promising electrochemical activities toward catalyzing the oxygen reduction reaction in both alkaline and acidic medium. An ultrahigh mass activity of 838 A g_Co^–1 at 0.9 V is achieved in the acidic electrolyte. This work suggests a new route to design SACs based on covalent organic framework for energy storage and conversion devices.     

Synthesis and characterization of Schiff base derivative with pyrrole ring and electrochromic applications of its oligomer

In this study, Schiff base monomer, 2-[(1H-pyrrol-2-yl-methylene)amino]phenol (2-PMAP) was obtained by condensation reaction of 2-aminophenol with pyrrole-2-carbaldehyde. This monomer was oxidized in an aqueous alkaline medium by NaOCl to obtain the corresponding oligomer (O-2-PMAP). The resulting compounds were characterized by ¹H- and ¹³C-NMR, FT-IR, UV–vis, TG-DTA and size exclusion chromatography (SEC) techniques. Metal complexes compounds of O-2-PMAP were prepared with various metal salts, such as Cu (AcO)₂·H₂O, Zn (AcO)₂·2H₂O, Cd (AcO)₂·2H₂O, Pb (AcO)₂·3H₂O and Co (AcO)₂·4H₂O. In addition to this, electrochemical copolymerization of O-2-PMAP with thiophene (Th), 3,4-ethylenedioxythiophene (EDOT) and pyrrole (Py) were performed onto indium/tin oxide (ITO)-coated glass plate. The spectral changes of the co-polymeric films were recorded in the range of the different potentials. The film stabilities of its EDOT and Py copolymers were determined. Consequently, it was realized that the copolymer films kept their stability for a long time.     

Continuous Covalent Organic Frameworks Membranes: From Preparation Strategies to Applications

Covalent organic frameworks (COFs) are porous crystalline polymeric materials formed by the covalent bonding of organic units. The abundant organic units library gives the COFs species diversity, easily tuned pore channels, and pore sizes. In addition, the periodic arrangement of organic units endows COFs regular and highly connected pore channels, which has led to the rapid development of COFs in membrane separations. Continuous defect-free and high crystallinity of COF membranes is the key to their application in separations, which is the most important issue to be addressed in the research. This review article describes the linkage types of covalent bonds, synthesis methods, and pore size regulation strategies of COFs materials. Further, the preparation strategies of continuous COFs membranes are highlighted, including layer-by-layer (LBL) stacking, in situ growth, interfacial polymerization (IP), and solvent casting. The applications in separation fields of continuous COFs membranes are also discussed, including gas separation, water treatment, organic solvent nanofiltration, ion conduction, and energy battery membranes. Finally, the research results are summarized and the future prospect for the development of COFs membranes are outlined. More attention may be paid to the large-scale preparation of COFs membranes and the development of conductive COFs membranes in future research.     

Iminium cations as intermediates in the hydrodenitrogenation of alkylamines over sulfided NiMo/γ-Al2O3

The mechanism of the hydrodenitrogenation of the mixed dialkyl- and trialkylamines C₁NHC₆ and C₁N(C₆)₂ was studied over sulfided NiMo/γ-Al₂O₃ at 280 °C and 3 MPa. C₁NHC₆ reacted by disproportionation to C₁N(C₆)₂ as well as C₆N(C₁)₂ and by substitution by H₂S to methylamine and hexanethiol as well as hexylamine and methanethiol. C₁N(C₆)₂ reacted by substitution with H₂S to C₁NHC₆ and C₆NHC₆ and methane- and hexanethiol. The probability of breaking the C₁N bond was only slightly smaller than of breaking the C₆N bond in C₁N(C₆)₂. In the reaction of an equimolar mixture of C₅NHC₅ and C₁N(C₆)₂ both C₁N(C₅)₂ and C₆N(C₅)₂ were formed. The transfer of the methyl group in these reactions cannot be explained by imine and enamine intermediates, only iminium cation intermediates can explain all the products in the hydrodenitrogenation of monoalkyl-, dialkyl- and trialkylamines.     

Electroactive Covalent Organic Frameworks: Design,Synthesis, and Applications

Covalent organic frameworks (COFs) are an emerging class of crystalline porous polymers with tailorable compositions, porosities, functionalities, and intrinsic chemical stability. The incorporation of electroactive moieties in the structure transforms COFs into electroactive materials with great potential for energy-related applications. Herein, the recent advances in the design and use of electroactive COFs as capacitors, batteries, conductors, fuel cells, water-splitting, and electrocatalysis are addressed. Their remarkable performance is discussed and compared with other porous materials; hence, perspectives in the development of electroactive COFs are presented.