Chemical Research in Chinese Universities

Themed Issue Dedicated to Professor Ruren Xu on the Occasion of his 90th Birthday

YU Jihong, ZHAO Dongyuan, YAN Wenfu

2022, 38(1): 1-4. doi:10.1007/s40242-022-1000-x

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Progress in Seed-assisted Synthesis of (Silico) Aluminophosphate Molecular Sieves

ZHANG Xiaosi, YANG Miao, TIAN Peng, LIU Zhongmin

2022, 38(1): 1-8. doi:10.1007/s40242-022-1407-4

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Aluminophosphate(AlPO) and silicoaluminophosphate(SAPO) molecular sieves are an important class of open-framework crystalline materials with wide applications thanks to their molecular-scale selectivity, moderate/strong acidity and excellent (hydro)thermal stability. In recent decades, the manufacturing of new microporous solids with ordered structures has been widely investigated and many effective methods have been developed, which enriches the material types and broadens their applications beyond the traditional use as catalysts and adsorbents. However, the development on the synthesis of AlPO/SAPO molecular sieves is still insufficient and lags behind the needs of applications. Herein, we summarize the work on the seed-assisted synthesis of AlPO/SAPO molecular sieves compared with the zeolite synthetic system, aiming to prompt the synthesis and application of AlPO/SAPO molecular sieves.

Synthesis of Pure Silica Zeolites

MI Zhenrui, LU Tingting, ZHANG Jia-Nan, XU Ruren, YAN Wenfu

2022, 38(1): 9-17. doi:10.1007/s40242-021-1383-0

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Pure silica zeolite has become an important porous material in the chemical industry due to its excellent stability and hydrophobicity. However, there are still some problems in the synthesis process of pure silica zeolite, such as environmental pollution, complex operation and high cost. How to effectively and environmentally synthesize pure silica zeolite still remains a significant challenge. This review summarizes the pure silica zeolitetype frameworks that have been discovered currently, introduces the progresses achieved in the synthesis of pure silica zeolite and prospects the areas for future exploration in the synthesis and development of pure silica zeolite.

Recent Advances of Porous Solids for Ultradilute CO₂ Capture

LIU Ru-Shuai, XU Shuang, HAO Guang-Ping, LU An-Hui

2022, 38(1): 18-30. doi:10.1007/s40242-021-1394-x

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The urgency of dealing with global climate change caused by greenhouse gas(GHG) emissions is increasing as the carbon dioxide(CO₂) concentration in the atmosphere has reached a record high value of 416 ppm(parts per million). Technologies that remove CO₂ from the surrounding air(direct air capture, DAC) could result in negative carbon emissions, and thus attracts increasing attention. The steady technical progress in adsorption-based CO₂ separation greatly advanced the DAC, which largely relies on advanced sorbent materials. This review focuses on the latest development of porous solids for air capture; first discussed the main types of sorbents for air capture, which include porous carbons, zeolites, silica materials, and metal-organic frameworks(MOFs), particularly their modified counterparts. Then, we evaluated their performances, including uptake and selectivity under dry and humid CO₂ streams for practical DAC application. Finally, a brief outlook on remaining challenges and potential directions for future DAC development is given.

Self-assembly of 3p-Block Metal-based Metal-Organic Frameworks from Structural Perspective

QIAO Junyi, LIU Xinyao, ZHANG Lirong, LIU Yunling

2022, 38(1): 31-44. doi:10.1007/s40242-021-1406-x

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Metal-organic frameworks(MOFs) are a class of porous inorganic-organic hybrid materials, which are constructed from diverse inorganic building units and multi-functional organic ligands. Highly ordered pore structures and tailored functionalization have made MOF materials potential for applications in many fields. Among various MOF materials, 3p-block metal(Al, Ga, and In)-based MOFs exhibit higher chemical stability than divalent transition metal-based MOFs due to their higher valence. In this review, Al-MOFs and In-MOFs were mainly discussed from the perspective of categories of inorganic building blocks, coordination types, and numbers of organic ligands. This review will give intuitive guidance to the design and synthesis of novel 3p-block metal-based MOFs with potential applications.

A Double Layer Laminated Film of Cellulose Nanocrystals and Dye Displaying Vibrant Circularly Polarized Light

WEI Lihong, MA Xiaoting, XU Yan

2022, 38(1): 45-49. doi:10.1007/s40242-021-1436-4

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Tailoring Porosity and Titanium Species of TS-1 Zeolites via Organic Base-assisted Sequential Post-treatment

XU Wenjing, LI Li, ZHANG Tianjun, YU Jihong

2022, 38(1): 50-57. doi:10.1007/s40242-021-1272-6

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The exploration of high-efficient catalysts based on hierarchical Ti-containing zeolites with optimized active titanium species distribution is of great value in enhancing the epoxidation of bulky olefins. Herein, hierarchical TS-1(MFI) zeolite with an extra-large external surface area(210 m²/g) and highly active octahedral- coordinated Ti species was prepared via organic base-assisted sequential post-treatment. Such a catalyst afforded a high turnover number value(TON, 114) in 1-octene epoxidation reaction, which was over twice than that(53) of the untreated conventional microporous TS-1 parent. According to the detailed characterization results, we revealed the hierarchical porosity construction effect of tetrapropylamonium hydroxide(TPAOH) treatment(first step) and the octahedral-coordinated Ti species fabrication effect of ethylamine(EA) treatment(second step) under hydrothermal condition. Such a facile post-treatment strategy reported in this work may provide guidance for the rational synthesis of TS-1 zeolite with enhanced catalytic activity.

Photo Switchable Two-step Photochromism in a Series of Ln-Phosphonate(Ln=Dy, Gd, Tb, Y) Dinuclear Complexes

HU Ji-Xiang, ZHANG Qian, XIA Bin, LIU Tao, PANG Jiandong, BU Xian-He

2022, 38(1): 58-66. doi:10.1007/s40242-021-1373-2

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Exploring the discrete complexes with multi-step coloration is still a challenge in the field of electron transfer photochromic materials. Herein, we synthesized a series of dinuclear Ln-diphosphonate compounds[Ln=Dy(1); Gd(2); Tb(3); Y(4)] with a remarkably and reversibly photoactive coloration phenomenon. These compounds showed two-step coloration behavior, which were the first discrete architectures in the reported electron transfer photochromic complexes. This two-step coloration phenomenon was originated from the large distortion of H₃-TPT acceptors, which in turn reduced the π-conjugation of electron acceptors and slowed the decay process of electron transfer. The photogenerated stable doublet radicals originated from electron transfer from diphosphonate donor to polypyridine acceptor in these complexes were detected by UV-Vis and electron spin resonance(ESR) spectra. Furthermore, the photogenerated radicals were estimated by direct current magnetic susceptibilities and variable temperature ESR spectra, suggesting the doublet radicals in the dinuclear structure for all the compounds. This work revealed a series of discrete phosphonate-based systems with a multi-step coloration process, providing a new pathway for designing multicolor photochromic materials with potential photoswitching or other applications.

Rational Design of Ratiometric Fe³⁺ Fluorescent Probes Based on FRET Mechanism

LI Mingfeng, FANG Hongbao, JI Yifan, CHEN Yuncong, HE Weijiang, GUO Zijian

2022, 38(1): 67-74. doi:10.1007/s40242-021-1398-6

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As the most abundant transition metal element in mammals, iron(Fe) plays a vital role in life activities. It is of great significance to study the variation of Fe³⁺ level in living organisms. In virtue of the advantages of high sensitivity, good selectivity and low damage to living systems, the fluorescence detection of Fe³⁺ has attracted much attention. Compared with the intensity-based fluorescent probe, the ratiometric fluorescent probe has less interference of environmental and can realize quantitative detection. In this study, four ratiometric Fe³⁺ fluorescent probes, R1, R2, R3 and R4_, were designed and synthesized using fluorescence resonance energy transfer(FRET) mechanism to achieve quantitative detection of Fe³⁺. In the FRET systems, 1,8-naphthalimide fluorophore derivatives were adopted as donors while rhodamine B derivatives were selected as receptors. The connection sites of the donor and acceptor in R3 and R4 are different from those in R1 and R2. All the four probes showed good response and selectivity to Fe³⁺. The energy transfer efficiencies of R3 and R4 were obviously higher than those of R1 and R2. This work provided a promising strategy for the development of fluorescent ratiometic Fe³⁺sensors.

Crystallographic Understanding of Photoelectric Properties for C₆₀ Derivatives Applicable as Electron Transporting Materials in Perovskite Solar Cells

XING Zhou, LI Shu-Hui, XU Piao-Yang, TIAN Han-Rui, DENG Lin-Long, YAO Yang-Rong, CHEN Bin-Wen, XIE Fang-Fang, AN Ming-Wei, YUN Da-Qin, XIE Su-Yuan, ZHENG Lan-Sun

2022, 38(1): 75-81. doi:10.1007/s40242-021-1264-6

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Hundreds of C₆₀ derivatives stand out as electrontransporting materials(ETMs), for example, in perovskite solar cells(PSCs), due to their properties on electron extraction or defect passivation. However, it still lacks of guidelines to update C₆₀-based ETMs with excellent photoelectric properties. In this work, crystallographic data of eight C₆₀-based ETMs, including pristine C₆₀ and the well-known PCBM as well as six newly synthesized fullerenes, are analyzed to establish the connections between derivatized structures and photoelectric properties for the typical carbon cluster of C₆₀. In terms of packing centroid-centroid distance between neighboring carbon cages, the crystallographic data are useful for probing photoelectric properties, such as electrochemical properties, electron mobility and photovoltaic performances, and therefore facilitate to design novel C₆₀-based ETMs for PSCs with high performances.

A Cage-based Porous Metal-Organic Framework for Efficient C₂H₂ Storage and Separation

LI Hengbo, WANG Kuikui, WU Mingyan, HONG Maochun

2022, 38(1): 82-86. doi:10.1007/s40242-021-1361-6

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Exploring the application potentials of metal-organic frameworks(MOFs) in the field of light hydrocarbons storage and separation is of great significance for solving the critical energy problem. However, designing porous materials with efficient separation capacity is still a challenging task. In this work, we synthesized a cage-based porous materiel(FJI-H32) with a large surface area. After activation, FJI-H32 exhibits the feature of high C₂H₂ storage capacity(113 cm³/g) and promising C₂H₂/CO₂ separation ability at 298 K and under 100 kPa. More importantly, the C₂H₂/CO₂ separation was verified by actual breakthrough experiments.

Microporous Zinc Formate for Efficient Separation of Acetylene over Carbon Dioxide

LI Jing-Hong, XIE Yi, ZHOU Mu-Yang, LIN Rui-Biao, CHEN Xiao-Ming

2022, 38(1): 87-91. doi:10.1007/s40242-021-1380-3

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Separation of acetylene(C₂H₂) from carbon dioxide(CO₂) by adsorbents is very challenging owing to their high similarity on molecular shape and dimension. Exploring inexpensive and easily available porous materials is of importance to facilitate the practical implementation of the challenging but energy-efficient separation. Herein, we utilize an easily available porous material[Zn₃(HCOO)₆] for the selective separation of C₂H₂ over CO₂. Because of the pore confinement in[Zn₃(HCOO)₆](pore size of 0.47 nm) and accessible oxygen sites for preferential binding of C₂H₂, this material exhibits high low-pressure uptake for C₂H₂(63 cm³/cm³ at 10 kPa and 298 K) and high C₂H₂/CO₂ selectivity(7.4 under ambient conditions) that is comparable to those of out-performing porous materials. The efficient separation of[Zn₃(HCOO)₆] for C₂H₂/CO₂ mixture has also been confirmed by the breakthrough experiments.

Loading Nickel Atoms on GDY for Efficient CO₂ Fixation and Conversion

ZHENG Zhiqiang, HE Feng, XUE Yurui, LI Yuliang

2022, 38(1): 92-98. doi:10.1007/s40242-021-1387-9

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Carbon dioxide(CO₂) is an important and valuable C1 resource for the synthesis of numerous of value-added products. However, efficient fixation and conversion of CO₂ into organic carbonates under mild conditions remain great challenges. Herein, graphdiyne(GDY)-based nickel atomic catalysts(Ni⁰/GDYs) were synthesized through a facile in-situ reduction method. Experimental results showed that the obtained Ni⁰/GDY had outstanding catalytic performances for converting CO₂ into cyclic carbonates with a high reaction conversion(99%) and reaction selectivity(ca. 100%) at 80℃ and under 1 atm(1 atm=101325 Pa). Specially, the activation energy (E_a) value for the Ni⁰/GDY is 37.05 kJ/mol, lower than those of reported catalysts. The reaction mechanism was next carefully analyzed by using density functional theory(DFT) calculations. Such an excellent catalytic property could be mainly attributed to the high dispersion of active sites on the Ni⁰/GDY, and the unique incomplete charge transfer properties of GDY-based zero-valent metallic catalysts.

Understanding on the Surfactants Engineered Morphology Evolution of Block Copolymer Particles and Their Precise Mesoporous Silica Replicas

YANG Shaobo, CAO Yuanyuan, WANG Shuqi, LI Yongsheng, SHI Jianlin

2022, 38(1): 99-106. doi:10.1007/s40242-021-1403-0

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Surfactant-directed block copolymer(BCP) particles have gained intensive attention owing to their attractive morphologies and ordered domains. However, their controllable fabrication suffers several limitations including complex design and synthesis of multiple surfactant systems, limited choices of block copolymers, and time-consuming post-processes, etc. Herein, a surfactant size-dependent phase separation route is proposed to precisely manipulate the architectures of the anionic block copolymer particles in the binary co-assembly system of BCP and surfactants. In the system of polystyrene block polyacrylic acid (PS-b-PAA) and quaternary ammonium surfactants, it is verified that facile control on the ordered phase separation structures and morphologies of BCP particles can be achieved via simply varying the alkyl lengths of the surfactants. The cationic surfactants are demonstrated participating in the fabrication of the internal structures of BCP particles. Especially, it is found that the cationic surfactants are integrate into the anionic polyacrylic acid(PAA) domain of BCP particles of PS-b-PAA to influence the volume fraction of PAA blocks, so that varied architectures of BCP particles are constructed. Based on these understandings, spherical or ellipsoidal BCP particles are obtained as expected, as well as their precisely inorganic mesoporous silica replicas through the block copolymer nanoparticle replicating route. More interestingly, the ellipsoidal mesoporous silica exhibits higher cellular internalization capability due to its lower energy expenditure during the internalization process, which presents promising potentials in biomedical applications, especially for high-efficient drug delivery systems. These findings may provide valuable insights into the confinement assembly of anionic block copolymers and the creation of special nanocarriers for high-efficiency biomacromolecule delivery in the biomedical community.

A Unique Layered Cu-formate Hydrate of Cu(HCOO) ₂·1/3H₂O: Structures, Dehydration, and Thermal and Magnetic Properties

FAN Huimin, WANG Bingwu, WANG Zheming, GAO Song

2022, 38(1): 107-116. doi:10.1007/s40242-022-1457-7

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Anew layered Cu-formate hydrate of Cu(HCOO)₂·1/3H₂O is unique in its water content and the strongly waved (4,4) Cu-formate layers held by interlayer weak axial Cu-O_formate bonds and O-H_water···O_formate hydrogen bonds. The crystal is in orthorhombic space group Pbcn, with cell parameters at 80 K:a=7.9777(2) Å, b=7.3656(2) Å, c=21.0317(5) Å(1 Å=10⁻¹ nm), and V=1235.83(5) Å³. The Cu²⁺ ions are in the environments of a square pyramid and elongated octahedron, in a ratio of 1/2 within the structure. In the layer, Cu²⁺ ions are connected by anti-anti formates via short basal Cu-O bonds. The structure remains unchanged until the dehydration that produces the layered anhydrous β-Cu(HCOO)₂, and the possible transformation mechanism, supported by diffraction evidence, is the reorganization of the Cu-O_formate bonds across the parent layers after dehydration. The two phases exhibit anisotropic thermal expansion behaviors closely relevant to the transverse thermal vibrations of the constituents. Cu(HCOO)₂·1/3H₂O is a 2-dimensional Heisenberg antiferromagnet, and exhibits a global spin-canted antiferromagnetism with the Néel temperature of 32.1 K. This is not only higher than that of the magnetically denser β-Cu(HCOO)₂, but also the highest among the copper formate frameworks.

Eliminating Hysteresis of Perovskite Solar Cells with Hollow TiO₂ Mesoporous Electron Transport Layer

HAN Wensheng, WANG Yongling, WAN Jiawei, WANG Dan

2022, 38(1): 117-122. doi:10.1007/s40242-022-1401-x

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Current density-voltage(J-V) hysteresis issue caused by unbalanced charge transport has greatly limited the improvement of power conversion efficiency(PCE) of halide perovskite solar cells(PSCs). Herein, hollow TiO₂ mesoporous electron transport layer(ETL) was used to fabricate PSCs. The structure-dependent charge collection as well as its effect on PCE and hysteresis impactor(HI) of PSC were investigated. The results demonstrate that TiO₂ hollow spheres in a size of around 50 nm (HS-50) can form a high quality perovskite/ETL interface with a less trap density. Moreover, the hollow TiO₂ with the thin shell can help promote the extraction of electrons from perovskite layer to ETL, so as to reduce the charge accumulation and recombination at the perovskite/ETL interface and alleviate the hysteresis behavior. As a result, PSCs with HS-50 TiO₂ delivered a champion PCE of 16.81% with a small HI of 0.0297, indicating a better performance than the commercial P25(PCE of 15.87%, HI of 0.2571).

A New Tubular Borate Built by[B₁₄O₂₄(OH) ₆]^12- Cluster Units

SUN Xiao-Shuang, QIN Dan, LI Xu-Yan, YANG Guo-Yu

2022, 38(1): 123-127. doi:10.1007/s40242-021-1183-6

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Anew mixed alkali and alkaline-earth metal borate Na₄Ca₂[B₁₄O₂₂(OH)₆]·2H₂O(1) has been made under a mild solvothermal condition and characterized by single-crystal X-ray diffraction, infrared(IR) spectroscopy, UV-Vis diffuse reflectance spectroscopy, powder X-ray diffraction and thermogravimetric analysis, respectively. Compound 1 features a 1D tube based on[B₁₄O₂₄(OH)₆]^12-({B₁₄}-1) oxo-boron clusters. Such a tube built by {B₁₄}-1 units has been discovered for the first time in borate system. These tubes are arranged orderly to generate 2D layers and a further 3D supramolecular network through hydrogen bond interactions. UV-Vis diffuse reflectance spectrum reveals that compound 1 is a wide band-gap semiconductor and has potential application in UV region.

Regulating the Deposition of Insoluble Sulfur Species for Room Temperature Sodium-Sulfur Batteries

WANG Chaozhi, CUI Jingqin, FANG Xiaoliang, ZHENG Nanfeng

2022, 38(1): 128-135. doi:10.1007/s40242-021-1273-5

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Room temperature sodium-sulfur(RT-Na-S) batteries are regarded as promising candidates for next-generation high-energy-density batteries. However, in addition to the severe shuttle effect, the inhomogeneous deposition of the insoluble sulfur species generated during the discharge/charge processes also contributes to the rapid capacity fade of RT-Na-S batteries. In this work, the deposition behavior of the insoluble sulfur species in the traditional slurry-coated sulfur cathodes is investigated using microporous carbon spheres as model sulfur host materials. To achieve uniform deposition of insoluble sulfur species, a self-supporting sulfur cathode fabricated by assembling microporous carbon spheres is designed. With homogeneous sulfur distribution and favorable electron transport pathway, the self-supporting cathode delivers remarkably enhanced rate capability(509 mA·h/g at 2.5 C, 1 C=1675 mA/g), cycling stability(718 mA·h/g after 480 cycles at 0.5 C) and areal capacity(4.98 mA·h/cm² at 0.1 C), highlighting the great potential of manipulating insoluble sulfur species to fabricate high-performance RT-Na-S batteries.

Sustainable Synthesis of Core-Shell Structured ZSM-5@Silicalite-1 Zeolite

LUAN Huimin, WU Qinming, ZHANG Jian, WANG Yeqing, MENG Xiangju, XIAO Feng-Shou

2022, 38(1): 136-140. doi:10.1007/s40242-021-1288-y

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Core-shell structured ZSM-5@Silicalite-1 zeolite could effectively hinder the deactivation of catalyst surface. Currently, organic structure directing agents(OSDAs) are necessary in the conventional route for the synthesis of this core-shell zeolite under hydrothermal conditions, which is costly and environmental-unfriendly. In this research, a synthesis of the core-shell structured ZSM-5@Silicalite-1 zeolite with a strategy of alcohol filling and zeolite seeding without any organic template or solvent is exhibited. The obtained products are well characterized by X-ray powder diffractometer(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), N₂ sorption isotherms, solid magic angle spinning(MAS) NMR, temperature-programmed-desorption of ammonia(NH₃-TPD), and X-ray photoelectron spectroscopy(XPS) techniques, in order to confirm the core-shell structure. More importantly, the core-shell structured ZSM-5@Silicalite-1 zeolite exhibits a long lifetime and a high p-xylene selectivity in the alkylation of toluene with methanol, compared with the conventional ZSM-5 catalyst.

Synthesis of Micro-Mesoporous Ti-MOR/Silica Composite Spheres in Oil-in-Water Microemulsion System

XU Hao, WANG Yanhong, PENG Rusi, JIANG Jingang, ZHANG Kun, WU Peng

2022, 38(1): 192-199. doi:10.1007/s40242-021-1321-1

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The hierarchically structured micro-mesoporous spheres(MMS) composed of mesoporous silica and Ti-containing mordenite (Ti-MOR) zeolite were self-assembled in an oil-in-water microemulsion system containing tetrabutyl orthosilicate as silica source, cetyltrimethylammonium bromide as template and aluminum sulfate as additive. The composite materials possessed the connatural microporosity of zeolite together with the disordered mesopores(5.41 nm) in silica part. With a special focus on the importance of aluminum sulfate additive, a possible formation mechanism has been proposed, in which double electrostatic interactions played the crucial role of mediating the mesosilica species and zeolite crystals. The obtained MMS materials, with a tunable particle dimension(250-720 μm) and a changeable content of active component Ti-MOR(44%-70%), showed enhanced catalytic activity and lifetime in the liquid-phase ammoximation of cyclohexanone in comparison to the parent Ti-MOR powder.

Boron-doped Covalent Triazine Framework for Efficient CO₂ Electroreduction

YI Jundong, LI Qiuxia, CHI Shaoyi, HUANG Yuanbiao, CAO Rong

2022, 38(1): 141-146. doi:10.1007/s40242-021-1384-z

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Converting CO₂ into chemicals with electricity generated by renewable energy is a promising way to achieve the goal of carbon neutrality. Carbon-based materials have the advantages of low cost, wide sources and environmental friendliness. In this work, we prepared a series of boron-doped covalent triazine frameworks and found that boron doping can significantly improve the CO selectivity up to 91.2% in the CO₂ electroreduction reactions(CO₂RR). The effect of different doping ratios on the activity by adjusting the proportion of doped atoms was systematically investigated. This work proves that the doping modification of non-metallic materials is a very effective way to improve their activity, and also lays a foundation for the study of other element doping in the coming future.

Towards High-performance Lithium-Sulfur Batteries: the Modification of Polypropylene Separator by 3D Porous Carbon Structure Embedded with Fe₃C/Fe Nanoparticles

LIU Yusi, ZHAO Xinghe, LI Sesi, ZHANG Qiang, WANG Kaixue, CHEN Jiesheng

2022, 38(1): 147-154. doi:10.1007/s40242-021-1386-x

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Lithium-sulfur(Li-S) batteries with high energy densities have received increasing attention. However, the electrochemical performance of Li-S batteries is still far from the satisfactory of the practical application, which can be mainly attributed to the shuttling of polysulfides and the slow reaction kinetics of polysulfide conversion. To address this issue, a 3D porous carbon structure constructed by 2D N-doped graphene and 1D carbon nanotubes with embedded Fe₃C/Fe nanoparticles(NG@Fe₃C/Fe) was designed and prepared by a simple programmed calcination method for the modification of polypropylene(PP) separator. The Fe₃C/Fe nanoparticles demonstrate an excellent catalytic conversion and strong chemisorption towards polysulfides, while the unique architecture of N-doped graphene promotes the Li⁺/electron transfer and the physical adsorption of polysulfides. The electrochemical performance of the Li-S batteries with the NG@Fe₃C/Fe-modified separator is significantly improved. A large discharge capacity of 1481 mA∙h∙g^-1 is achieved at 0.2 C(1 C=1675 mA/g), and a high capacity of 601 mA∙h∙g^-1 is maintained after discharged/charged for 500 cycles at a current rate of 1 C. This work provides a new approach for the development of high-performance Li-S batteries through the modification of the PP separator by rationally designed composites with large adsorption capability to polysulfides, good wettability to the electrolyte and high catalytic property.

Mechanistic Insight into Ethanol Dehydration over SAPO-34 Zeolite by Solid-state NMR Spectroscopy

ZHOU Xue, WANG Chao, CHU Yueying, WANG Qiang, XU Jun, DENG Feng

2022, 38(1): 155-160. doi:10.1007/s40242-022-1450-1

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The reaction mechanism of ethanol dehydration over SAPO-34 zeolite is investigated by using solid-state NMR spectroscopy. SAPO-34 zeolites with different Si contents are prepared and their acidities are characterized by NMR experiments. The higher content of stronger Brønsted acid sites is correlated to the higher Si content. The adsorption of ethanol on the Brønsted acid sites in SAPO-34 leads to the formation of frustrated Lewis pairs(FLPs). Surface ethoxy species is observed by the dehydration of the FLP sites at room temperature, which can be further converted into ethene products. The decomposing of diethyl ether over Brønsted acid sites is responsible for the formation of ethoxy species at higher reaction temperatures. Triethyloxonium ions are formed in the reaction. A plausible reaction mechanism is proposed for the dehydration of ethanol over SAPO-34.

High-throughput Screening of Aluminophosphate Zeolites for Adsorption Heat Pump Applications

SHI Chao, WANG Jiaze, LI Lin, LI Yi

2022, 38(1): 161-166. doi:10.1007/s40242-021-1335-8

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Owing to their high porosity, high water sorption capacity, and thermal stability, aluminophosphate(AlPO) zeolites have shown promising applications in adsorption heat pump(AHP) systems to utilize low-temperature waste heat from heat sources. To accelerate the development of new high-efficiency AHP adsorbents, we report a high-throughput grand canonical Monte Carlo(GCMC) approach to predict the heat storage capabilities of 78 known and 84292 hypothetical AlPO zeolites. We employ three evaluation metrics, including water working capacity, energy density, and regenerability, to comprehensively evaluate the performance of these AlPO structures. Finally, we identify 29 promising candidates with water adsorption properties superior to the commercial adsorbent AQSOA-Z02. This is the first study in large-scale screening of AlPO zeolites for water adsorption. The obtained results will provide important guidance toward the experimental discovery of high-performance AlPO zeolites for AHP applications.

A Nitrogen, Sulfur co-Doped Porphyrin-based Covalent Organic Framework as an Efficient Catalyst for Oxygen Reduction

YU Xiaoming, MA Yunchao, LI Cuiyan, GUAN Xinyu, FANG Qianrong, QIU Shilun

2022, 38(1): 167-172. doi:10.1007/s40242-021-1374-1

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Oxygen reduction reaction(ORR) is a significant reaction for energy conversion systems(such as fuel cells, metal-air batteries, etc.). It is an urgent need to develop cheap, durable and highly-active catalysts for efficient ORR. Hence, we report a metal-free nitrogen and sulfur co-doped porphyrin-based covalent organic framework(COF) as a high-efficiency ORR catalyst[the onset potential(E_o) is 0.79 V and the half-wave potential(E_1/2) is 0.70 V]. The double doping of N and S atoms causes uneven charge distribution around carbon atoms, which can act as catalytic active centers, improving ORR activity. Compared with single-atom doping, double atoms doping exhibits a higher activity due to the synergistic effect between different elements. These results demonstrate that reasonable design of stable metal-free COFs with a high electrochemical activity can promote their wide applications.

Catalytic Hydration of Aromatic Alkynes to Ketones over H-MFI Zeolites

ZHANG Yunzhe, DAI Weili, WU Guangjun, GUAN Naijia, LI Landong

2022, 38(1): 173-180. doi:10.1007/s40242-021-1209-0

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The hydration of alkyne represents the most straightforward and simplest route toward the synthesis of ketone. Herein, Brønsted acidic zeolites are explored as potential catalysts for the liquid-phase phenylacetylene hydration. The topology structure and Si/Al ratio are disclosed to be key factors controlling the catalytic activity of zeolites. Typically, H-MFI zeolite with a Si/Al molar ratio of 13 exhibits the highest catalytic activity, with turnover frequency of 6.0 h^-1 at 363 K. Besides, H-MFI zeolite shows good catalytic stability and recyclability in the reaction of phenylacetylene hydration, and the substrate scope can be simply extended to other soluble aromatic alkynes. The reaction mechanism of phenylacetylene hydration is investigated by means of kinetic and spectroscopic analyses. The Markovnikov electrophilic addition of phenylacetylene by hydrated protons is established as the rate-determining step, followed by deprotonation and enol isomerization to derive acetophenone product.

Solid-state[2+2] Photocycloaddition Reaction of Zinc(II) Complex Based on Quaternized 1,2-Bis(4'-pyridyl) ethylene

JIA Mengze, SUN Li, CHEN Yunrui, ZHANG Jie

2022, 38(1): 181-185. doi:10.1007/s40242-021-1226-z

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Aphotoactive metal-organic complex[Zn₂(BCbpe)₂(p-DBC)₂]∙

5H₂O(1) has been synthesized based on an olefin-containing pyridinium compound, 1-(4-carboxybenzyl)-4-[2-(4-pyridyl)-vinyl]pyridinium chloride(HBCbpeCl), and characterized by single-crystal X-ray diffraction, IR spectroscopy, powder X-ray diffraction and thermogravimetric analysis, respectively. In the solid state, the BCbpe ligands are packed in a head-to-tail manner through weak cation-π interaction, undergoing a photo-induced cycloaddition quantitatively upon UV-light irradiation.

Metal-Organic Framework-based Wood Aerogel for Effective Removal of Micro/Nano Plastics

YOU Dongyu, ZHAO Yujuan, YANG Weiting, PAN Qinhe, LI Jiyang

2022, 38(1): 186-191. doi:10.1007/s40242-021-1317-x

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The large amount of microplastic pollution in the aquatic environment has been regarded as a major challenge facing the world. Although some traditional water treatment processes can effectively remove microplastics in the millimeter range, research is still needed to solve the problem of removing smaller microplastics. Here, we made a durable zinc metal-organic framework-based composite material ZIF-8@Aerogel by in situ growing ZIF-8 on wood aerogel fibers, which can successfully remove microplastics in simulated water and seawater. The removal efficiencies on micro/nano plastics including poly(1,1-difluoroethylene)(60-110 nm) and polystyrene(90-140 nm) reached 91.4% and 85.8%, respectively. This work is expected to provide a new and efficient way to remove small-sized microplastic particles in the environment.

Nature-inspired Three-dimensional Au/Spinach as a Binder-free and Self-standing Cathode for High-performance Li-O₂ Batteries

WANG Yue, WANG Xiaoxue, SHE Ping, GUAN Dehui, SONG Lina, XU Jijing

2022, 38(1): 200-208. doi:10.1007/s40242-021-1339-4

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Design and fabrication of functional porous air cathode materials with superior catalytic activity is still the key point for non-aqueous lithium-oxygen(Li-O₂) batteries. Herein, inspired by the self-standing three-dimensional(3D) structure of the natural spinach leaves, a unique binder-free and self-standing porous Au/spinach cathode for high-performance Li-O₂ batteries has been developed. The carbonized spinach leaves serve as a superconductive current collector and an ideal porous host for accommodating catalysts. The Au/spinach cathode could offer enough spaces for accommodating the discharge products, shorten the distance of the oxygen and electrolyte diffusion, and promote the oxygen reduction reaction(ORR) and oxygen evolution reaction (OER) processes. This optimized Au/spinach cathode achieved a high specific area capacity of 7.23 mA‧h/cm² at a current density of 0.05 mA/cm² and exhibited excellent stability(280 cycles at 0.05 mA/cm² with a fixed capacity of 0.2 mA‧h/cm²). The superior performance encourages the construction of more advanced cathode architectures by the use of bio-composites for Li-O₂ batteries.

Coordination Polymers with Bipyridyl Diene and Triene Ligands: Synthesis, Structures and Luminescent Properties

HUA Chen, YI Pin, LIU Wencong, WANG Mengfan, NIU Zheng, LANG Jianping

2022, 38(1): 209-216. doi:10.1007/s40242-021-1352-7

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Solvothermal reactions of cadmium salts with bipyridyl diene and triene ligands[1,3-bis((E)-2-(pyridin-4-yl)vinyl)benzene-(1,3-bpeb) and 1,6-bis(4-pyridyl)-1,3,5-hexatriene(bphte)] and one bipyridyl triene ligand[1,6-bis(4-pyridyl)-1,3,5-hexatriene-(bphte)] in the presence of auxiliary carboxylic acids including 2,6-dichlorobenzoic acid(2,6-HDCBA) and 2-naphthal-enecarboxylic acid(2-HNCA) gave rise to four coordination polymers[Cd(bphte)(2,6-DCBA)₂]_n(1), {[Cd(bphte)(2-NCA)₂]·5.8H₂O}_n(2),[Cd₂(1,3-bpeb)₂(2,6-DCBA)₄]_n(3) and {[Cd₄(1,3-bpeb)₄(2-NCA)₇(HCOO)]·

2-HNCA·H₂O}_n(4), respectively. Compounds 1-4 were structurally characterized by elemental analysis, IR, ¹H NMR, powder X-ray diffraction, thermogravimetric analysis and single-crystal X-ray diffraction. They possess one-dimensional linear(1, 2) and zigzag(3, 4) chain structures. Their luminescent properties were explored while the representative sample 4 exhibited good luminescent performance in sensing Fe(III) in water.

Remote Synthesis of Layered Double Hydroxide Nanosheets Through the Automatic Chemical Robot

WANG Zelin, LIU Guihao, SHEN Tianyang, TAN Ling, ZHAO Yufei, SONG Yu-Fei

2022, 38(1): 217-222. doi:10.1007/s40242-021-1358-1

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As a family of two-dimensional functional materials, layered double hydroxides(LDHs) have the characteristics of adjustable lamellar element type and proportion, variable interlamellar anion, controllable particle size and thickness, providing a robust platform for photo/electro/thermal-catalysis. With the continuous progress of materials science, the synthesis of LDHs is becoming more and more refined. Herein, to achieve the fine preparation of LDHs materials, especailly for the no-chemical/material researchers, we successfully assembled the automatic synthesis device and wrote corresponding computer software to control this device, and the automatic synthesis of bulk and monolayer LDHs nanosheets on a laboratory scale can be realized. This work paves a new labor-saving way for the fine synthesis of LDHs nanostructures, further improving the development of LDHs-based materials.

Conversion of CO₂ to Multi-carbon Compounds over a CoCO₃ Supported Ru-Pt Catalyst Under Mild Conditions

HUANG Jin, CAI Yichen, YU Yulv, WANG Yuan

2022, 38(1): 223-228. doi:10.1007/s40242-021-1382-1

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The catalytic hydrogenation of CO₂ to multi-carbon compounds under mild conditions would not only provide value-added products, but also benefit for the reduction of CO₂ emission if hydrogen derives from renewable energy sources. Herein, we report CoCO₃ supported Ru and Pt nano-particles, which could catalyze hydrogenation of CO₂ to produce higher hydrocarbons(C₂-C₂₆) and higher alcohols(C₂OH-C₆OH) at low temperatures of 80-130℃. The selectivity for C₂₊ compounds reached 81.1% at 80℃, which was the highest value reported so far. This work provides a promising catalyst for highly selective converting CO₂ and H₂ to C₂₊ compounds at low temperatures.

Influence of the ZSM-5 Support Acidity on the Catalytic Performance of Pd/ZSM-5 in Lean Methane Oxidation

LUO Li, WANG Sen, WU Zhiwei, QIN Zhangfeng, DONG Mei, WANG Jianguo, FAN Weibin

2022, 38(1): 229-236. doi:10.1007/s40242-021-1391-0

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Although zeolites are characterized by their special acidic properties, there is still no clear consensus on the effect of zeolite support acidity on the catalytic activity of supported Pd catalyst in methane oxidation. Herein, a series of Pd/H-ZSM-5 and Pd/Silicalite-1 catalysts was prepared by the deposition-precipitation method and used in lean methane oxidation. The effect of ZSM-5 support acidity on the catalytic performance of Pd/ZSM-5 was investigated. The results indicate that with the decrease of Si/Al ratio(x), viz., the increase of acid sites in H-ZSM-5(x), the catalytic activity of Pd/H-ZSM-5(x) increases substantially; the activity of various catalysts in the lean methane oxidation decreases in the order of Pd/H-ZSM-5(28)>Pd/H-ZSM-5(48)>Pd/H-ZSM-5(88)>Pd/H-ZSM-5(204)>Pd/Silicalite-1. Furthermore, various characterization measures reveal that the catalytic activity of Pd/H-ZSM-5(x) in lean methane oxidation is mainly related to the Lewis acid sites in the H-ZSM-5 support, whereas less relevant to the Brønsted acid sites. The abundant Lewis acid sites in H-ZSM-5 are capable to enhance the interaction between the Pd species and H-ZSM-5 support, which can inhibit the agglomeration of Pd particles and improve the dispersion of Pd species, and thus boost the catalytic activity of Pd/H-ZSM-5 in methane oxidation.

Molten Salts Strategy for the Synthesis of CoP Nanoparticles Entrapped, N,P co-Doped Mesoporous Carbons as Electrocatalysts for Hydrogen Evolution

XU Jing, MIAO Sijia, TANG Duihai, ZHANG Wenting, ZHAO Zhen, QIAO Zhen-An

2022, 38(1): 237-242. doi:10.1007/s40242-021-1402-1

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Amolten salt process was developed to prepare CoP nanoparticles(NPs) embedded, N,P co-doped carbons with the combination of hand milling and high temperature carbonization. The characterization results implied that the as-prepared samples possessed mesoporous structures. Moreover, the mass ratios of the precursors affected the crystalline structures and the porosities of the final electrocatalysts. The as-prepared catalysts exhibited excellent electrocatalytic performances towards hydrogen evolution reaction(HER) under acidic and alkaline conditions. The as-prepared samples were designed as GxMyCoz, where x, y and z meant the amounts of glucose, melamine and CoCl₂, respectively. The optimum sample of G6.0M2.0Co5.0 showed the best HER property with a low onset overpotential and a small Tafel slope, as well as excellent electrocatalytic stability.

Synthesis of FER Zeolite Using 4-(Aminomethyl) pyridine as Structure-directing Agent

LIANG Jun, FU Wenhua, LIU Chuang, LI Xiangcheng, WANG Yu, MA Duozheng, LI Yuekun, WANG Zhendong, YANG Weimin

2022, 38(1): 243-249. doi:10.1007/s40242-021-1404-z

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This paper describes the synthesis of FER zeolite using commercially available 4-(aminomethyl)pyridine as organic structure-directing agent(OSDA). FER zeolites were prepared in mixtures with SiO₂/Al₂O₃ molar ratios in a narrow range and the resultant products possessed a typical flake-shaped morphology. The crystallization of FER zeolite was tracked in order to better understand the formation mechanism and the products obtained at different crystallization time were systematically characterized using multiple techniques. It showed that a majority of Si atoms and nearly all the Al atoms transformed into the solid phase during the hydrothermal synthesis. The rearrangement of inorganic species gave rise to zeolitic 5-membered rings(5-MRs) and 6-membered rings(6-MRs). Consequently, FER zeolite crystals were formed by the consumption of amorphous bulky gel/solid matrix. Tracking the synthesis process of FER can help.

Synthesis Optimization of SSZ-13 Zeolite Membranes by Dual Templates for N₂/NO₂ Separation

LI Jun, RONG Huazhen, CHEN Cong, LI Ziyi, ZUO Jiayu, WANG Wenjian, LIU Xinjian, GUAN Yixing, YANG Xiong, LIU Yingshu, ZOU Xiaoqin, ZHU Guangshan

2022, 38(1): 250-256. doi:10.1007/s40242-021-1420-z

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High-silica SSZ-13 zeolite membranes are promising in industrial separations of light gases and continuous membranes are highly demanded for better separation performances. Herein, pure-phase, continuous and thin SSZ-13 zeolite membranes were synthesized using dual templates of N,N,N-trimethtyl-1-adamantammonium hydroxide(TMAdaOH) and tetraethylammonium hydroxide(TEAOH). Systematical investigations of TMAdaOH/TEAOH ratios and their concentrations show that TMAdaOH acts as the main structure-directing agent in the formation of the SSZ-13 zeolite. TMAdaOH cooperatively plays with TEAOH in promoting the SSZ-13 crystal intergrowth to form a continuous polycrystalline membrane. Additionally, appropriate introduction of TEAOH is able to adjust the membrane thickness to the crystal-comparable size of ca. 2.0 μm. The SSZ-13 membranes are further applied for N₂/NO₂separation, which is firstly reported on zeolite membranes. The gas permeation results show that the SSZ-13 membrane synthesized by the dual-template approach exhibits selective separation of N₂ over NO₂ with N₂/NO₂ separation factor of 7.6 and N₂ permeance of 1.66×10^-8 mol·m^-2·s^-1·Pa^-1.

Insights into the Active Acid Sites for Isosorbide Synthesis from Renewable Sorbitol and Cellulose on Solid Acid Catalysts

DENG Tianyin, HE Xiaohui, LIU Haichao

2022, 38(1): 257-264. doi:10.1007/s40242-022-1499-x

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Sustainable synthesis of isosorbide, an important renewable platform chemical, from sorbitol and cellulose, has attracted increasing attention, but still remains challenging. Here, we have studied the effects of the acidity on the dehydration of sorbitol in water on a variety of solid acids, including zeolites, sulfonic materials, montmorillonite and mixed SiO₂-Al₂O₃ oxide. These solid acids showed markedly different activities, which were found to be closely related to their strong Brønsted acid sites, while the weak Brønsted acid and Lewis acid sites were essentially inactive. Different from the other solid acids examined, H-ZSM-5 zeolites in a wide range of Si/Al molar ratios(25-300) exhibited superior selectivities to isosorbide in dehydration of sorbitol, consistent with the observed difference in their formation rates of the 1,4-sortbitan and 3,6-sorbitan intermediates. Kinetic studies on the sorbitol dehydration showed that 3,6-sorbitan, once it formed, dehydrated to isosorbide more readily than 1,4-sorbitan by a factor of 19, and the formation rate constant of 3,6-sorbitan on H-ZSM-5(Si/Al=25) was about three times higher than that of H-Beta(Si/Al=25). Such favorable formation of the reactive 3,6-sorbitan intermediate and the higher isosorbide selectivity on H-ZSM-5 appear to be induced by its confined pore structure composed of the paired 5-membered rings. H-ZSM-5 was also found to be efficient for the direct conversion of cellulose to isosorbide in coupling with Ru/C hydrogenation catalyst. This work provides fundamental insights into the acidity and pore structures that are helpful for the design of novel solid acids toward the efficient synthesis of isosorbide from the dehydration of sorbitol and even directly from the tandem reaction of cellulose.

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