A Robust Molecular Porous Material for C2H2/CO2 Separation

A molecular porous material, MPM-2, comprised of cationic [Ni₂(AlF₆)(pzH)₈(H₂O)₂] and anionic [Ni₂Al₂F₁₁(pzH)₈(H₂O)₂] complexes that generate a charge-assisted hydrogen-bonded network with pcu topology is reported. The packing in MPM-2 is sustained by multiple interionic hydrogen bonding interactions that afford ultramicroporous channels between dense layers of anionic units. MPM-2 is found to exhibit excellent stability in water (>1 year). Unlike most hydrogen-bonded organic frameworks which typically show poor stability in organic solvents, MPM-2 exhibited excellent stability with respect to various organic solvents for at least two days. MPM-2 is found to be permanently porous with gas sorption isotherms at 298 K revealing a strong affinity for C₂H₂ over CO₂ thanks to a high (ΔQ_st)_AC [Q_st (C₂H₂) − Q_st (CO₂)] of 13.7 kJ mol⁻¹ at low coverage. Dynamic column breakthrough experiments on MPM-2 demonstrated the separation of C₂H₂ from a 1:1 C₂H₂/CO₂ mixture at 298 K with effluent CO₂ purity of 99.995% and C₂H₂ purity of >95% after temperature-programmed desorption. C-H···F interactions between C₂H₂ molecules and F atoms of AlF₆³⁻ are found to enable high selectivity toward C₂H₂, as determined by density functional theory simulations.     

Electrospun N‐Doped Porous Carbon Nanofibers Incorporated with NiO Nanoparticles as Free‐Standing Film Electrodes for High‐Performance Supercapacitors and CO2 Capture

Carbon nanofibers (CNF) with a 1D porous structure offer promising support to encapsulate transition‐metal oxides in energy storage/conversion relying on their high specific surface area and pore volume. Here, the preparation of NiO nanoparticle‐dispersed electrospun N‐doped porous CNF (NiO/PCNF) and as free‐standing film electrode for high‐performance electrochemical supercapacitors is reported. Polyacrylonitrile and nickel acetylacetone are selected as precursors of CNF and Ni sources, respectively. Dicyandiamide not only improves the specific surface area and pore volume, but also increases the N‐doping level of PCNF. Benefiting from the synergistic effect between NiO nanoparticles (NPs) and PCNF, the prepared free‐standing NiO/PCNF electrodes show a high specific capacitance of 850 F g^?1 at a current density of 1 A g^?1 in 6 m KOH aqueous solution, good rate capability, as well as excellent long‐term cycling stability. Moreover, NiO NPs dispersed in PCNF and large specific surface area provide many electroactive sites, leading to high CO₂ uptake, and high‐efficiency CO₂ electroreduction. The synthesis strategy in this study provides a new insight into the design and fabrication of promising multifunctional materials for high‐performance supercapacitors and CO₂ electroreduction.     

相变溶剂吸收CO2研究进展

二氧化碳捕集是应对全球变暖的有效途径,溶剂吸收法是目前最为成熟的二氧化碳燃烧后捕集技术,但过高的二氧化碳解吸能耗是限制其进一步推广的瓶颈。相变溶剂吸收CO2由于有再生能耗低的优点,受到了越来越多研究者的关注。综述了有机胺溶剂吸收CO2的反应机理,并介绍了传统溶剂吸收CO2的装置和吸收CO2的各种方法。重点阐述了热致相变溶剂吸收CO2的热力学计算方法、临界溶解温度、热致相变原理和其溶剂选择标准,在此基础上,综述了热致相变溶剂的研究现状。最后概述了近年来国内外其他相变溶剂吸收CO2的研究进展。     

Efficient Mercury Capture Using Functionalized Porous Organic Polymer

The primary challenge in materials design and synthesis is achieving the balance between performance and economy for real‐world application. This issue is addressed by creating a thiol functionalized porous organic polymer (POP) using simple free radical polymerization techniques to prepare a cost‐effective material with a high density of chelating sites designed for mercury capture and therefore environmental remediation. The resulting POP is able to remove aqueous and airborne mercury with uptake capacities of 1216 and 630 mg g^?1, respectively. The material demonstrates rapid kinetics, capable of dropping the mercury concentration from 5 ppm to 1 ppb, lower than the US Environmental Protection Agency's drinking water limit (2 ppb), within 10 min. Furthermore, the material has the added benefits of recyclability, stability in a broad pH range, and selectivity for toxic metals. These results are attributed to the material's physical properties, which include hierarchical porosity, a high density of chelating sites, and the material's robustness, which improve the thiol availability to bind with mercury as determined by X‐ray photoelectron spectroscopy and X‐ray absorption fine structure studies. The work provides promising results for POPs as an economical material for multiple environmental remediation applications.     

掺氮多孔碳在二氧化碳吸附分离中的应用

CO₂作为温室气体, 其捕集和存储有着重要的现实意义。多孔碳材料掺杂N原子后可以极大地改变材料的表面化学性质, 增强表面碱性, 在CO₂吸附领域具有广泛的应用。基于N掺杂最新研究进展, 本文系统地介绍了原位、后处理等掺N方法和不同孔道结构对CO₂吸附分离或扩散传质的影响, 总结归纳了材料的物理结构参数、表面化学性质与CO₂吸附分离性能的关系, 指出了各种制备方法存在的问题及解决的方法, 为高性能的CO₂吸附剂的定向设计、制备以及工业化提供了理论参考。     

Specific K+ Binding Sites as CO2 Traps in a Porous MOF for Enhanced CO2 Selective Sorption

Metal–organic frameworks (MOFs) can be fine‐tuned to boost sorbent‐sorbate interactions in order to improve gas sorption and separation performance, but the design of MOFs with ideal structural features for gas separation applications remains a challenge. Herein it is reported that unsaturated alkali metal sites can be immobilized in MOFs through a tetrazole based motif and that gas affinity can thereby be boosted. In the prototypal MOF of this type‐ NKU‐521 (NKU denotes Nankai University), K⁺ cations are effectively embedded in a trinuclear Co²⁺‐tetrazole coordination motif. The embedded K⁺ sites are exposed to the pores of NKU‐521 through water removal, and the isosteric heat (Q_st) for CO₂ is boosted to 41 kJ mol^‐1. The nature of the binding site is validated by molecular simulations and structural characterization. The K⁺ cations in effect serve as gas traps and boost the CO₂‐framework affinity, as measured by the Q_st, by 24%. In addition, the impact of unsaturated alkali metal sites upon the separation of hydrocarbons is evaluated for the first time in MOFs using ideal adsorbed solution theory (IAST) calculations and column breakthrough experiments. The results reveal that the presence of exposed K⁺ sites benefits gas sorption and hydrocarbon separation performances of this MOF.     

阴离子功能化超微孔MOF高效选择性捕获低浓度CO2

CO2捕获,尤其低浓度CO2捕获,对人类在限域空间中长时间工作、降低天然气液化过程中CO2腐蚀及冻结效应极为重要.本文首次报道了一种具有一维孔道的ZU-16-Co(TIFSIX-3-Co)材料,该材料孔道中含大量电负性F原子,可实现400–10,000 ppm浓度下CO2的高效捕获.相比同构材料,孔径为3.62?的ZU...     

Metallic Cobalt–Carbon Composite as Recyclable and Robust Magnetic Photocatalyst for Efficient CO2 Reduction

CO₂ conversion into value‐added chemical fuels driven by solar energy is an intriguing approach to address the current and future demand of energy supply. Currently, most reported surface‐sensitized heterogeneous photocatalysts present poor activity and selectivity under visible light irradiation. Here, photosensitized porous metallic and magnetic 1200 Co C composites (PMMCoCC‐1200) are coupled with a [Ru(bpy)₃]Cl₂ photosensitizer to efficiently reduce CO₂ under visible‐light irradiation in a selective and sustainable way. As a result, the CO production reaches a high yield of 1258.30 µL with selectivity of 64.21% in 6 h, superior to most reported heterogeneous photocatalysts. Systematic investigation demonstrates that the central metal cobalt is the active site for activating the adsorbed CO₂ molecules and the surficial graphite carbon coating on cobalt metal is crucial for transferring the electrons from the triplet metal‐to‐ligand charge transfer of the photosensitizer Ru(bpy)₃²⁺, which gives rise to significant enhancement for CO₂ reduction efficiency. The fast electron injection from the excited Ru(bpy)₃²⁺ to PMMCoCC‐1200 and the slow backward charge recombination result in a long‐lived, charge‐separated state for CO₂ reduction. More impressively, the long‐time stability and easy magnetic recycling ability of this metallic photocatalyst offer more benefits to the photocatalytic field.     

Nanostructured Carbon Nitrides for CO2 Capture and Conversion

Carbon nitride (CN), a 2D material composed of only carbon (C) and nitrogen (N), which are linked by strong covalent bonds, has been used as a metal-devoid and visible-light-active photocatalyst owing to its magnificent optoelectronic and physicochemical properties including suitable bandgap, adjustable energy-band positions, tailor-made surface functionalities, low cost, metal-free nature, and high thermal, chemical, and mechanical stabilities. CN-based materials possess a lot of advantages over conventional metal-based inorganic photocatalysts including ease of synthesis and processing, versatile functionalization or doping, flexibility for surface engineering, low cost, sustainability, and recyclability without any leaching of toxic metals from photocorrosion. Carbon nitrides and their hybrid materials have emerged as attractive candidates for CO₂ capture and its reduction into clean and green low-carbon fuels and valuable chemical feedstock by using sustainable and intermittent renewable energy sources of sunlight and electricity through the heterogeneous photo(electro)catalysis. Here, the latest research results in this field are summarized, including implementation of novel functionalized nanostructured CNs and their hybrid heterostructures in meeting the stringent requirements to raise the efficiency of the CO₂ reduction process by using state-of-the-art photocatalysis, electrocatalysis, photoelectrocatalysis, and feedstock reactions. The research in this field is primarily focused on advancement in the synthesis of nanostructured and functionalized CN-based hybrid heterostructured materials. More importantly, the recent past has seen a surge in studies focusing significantly on exploring the mechanism of their application perspectives, which include the behavior of the materials for the absorption of light, charge separation, and pathways for the transport of CO₂ during the reduction process.     

氨基改性CO2固体吸附材料的研究进展

以固态胺吸附剂和CO2吸附性能为主线,综述了改性剂的类型以及氨基负载的碳基、沸石、硅基、聚合物等CO2固体吸附剂的研究进展及优缺点,并对改性的硅基吸附剂的吸附性能的影响因素进行了讨论,如水的存在、温度以及CO2分压等,指出改性剂的选择以及分子筛的物理化学性质是未来CO2吸附的研究趋势.     

CO2/N2分离中水合物膜形成的影响因素研究

温室效应是如今人类所面临的一个重大问题,而二氧化碳对温室效应的"贡献"最大,因此发展研究捕集CO2的新型高效节能技术及相关理论,对避免温室效应,保护环境具有极其重要的意义.本文提出了将膜分离法和水合物法结合起来即水合物膜法,并利用自行组建的水合物膜法分离二氧化碳实验系统初步探索了多孔陶瓷管的孔径,体系的压力、温度、气体...     

Strain-Engineering of Mesoporous Cs3Bi2Br9/BiVO4 S-Scheme Heterojunction for Efficient CO2 Photoreduction

Slow charge kinetics and unfavorable CO₂ adsorption/activation strongly inhibit CO₂ photoreduction. In this study, a strain-engineered Cs₃Bi₂Br₉/hierarchically porous BiVO₄ (s-CBB/HP-BVO) heterojunction with improved charge separation and tailored CO₂ adsorption/activation capability is developed. Density functional theory calculations suggest that the presence of tensile strain in Cs₃Bi₂Br₉ can significantly downshift the p-band center of the active Bi atoms, which enhances the adsorption/activation of inert CO₂. Meanwhile, in situ irradiation X-ray photoelectron spectroscopy and electron spin resonance confirm that efficient charge transfer occurs in s-CBB/HP-BVO following an S-scheme with built-in electric field acceleration. Therefore, the well-designed s-CBB/HP-BVO heterojunction exhibits a boosted photocatalytic activity, with a total electron consumption rate of 70.63 µmol g⁻¹ h⁻¹, and 79.66% selectivity of CO production. Additionally, in situ diffuse reflectance infrared Fourier transform spectroscopy reveals that CO₂ photoreduction undergoes a formaldehyde-mediated reaction process. This work provides insight into strain engineering to improve the photocatalytic performance of halide perovskite.