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10 November 2020, Volume 41 Issue 11

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Cover and Content of Chemical Journal of Chinese Universities Vol.41 No.11(2020)

2020, 41(11):  0-0. 

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Theoretical Study on the Construction and Characteristics of the Host-guest Intercalated Structure of Layered Double Hydroxides

ZHU Yuquan, ZHAO Xiaojie, ZHONG Yuan, CHEN Ziru, YAN Hong, DUAN Xue

2020, 41(11):  2287-2305.  doi:10.7503/cjcu20200404

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Due to the large variety of the layer cations and interlayer anions， layered double hydroxides （LDHs） have shown the applications in the fields of catalyst， adsorption， biomedicine and optics， electricity and magnetism. Theoretical methods have become the powerful tools to uncover the microstructure and properties of LDHs. Herein， we systematically summarize the recent research progress in the field of theoretical studies on the host structure， guest structure and host-guest interaction of LDHs， and its application as an optical-driven catalyst， including the type of the layer cations， the composition of the cations， charge distribution， topotactic transformation mechanism， band structure， density of states， orientation of interlayer anions， ion-exchange properties， host-guest interaction， energy properties， and photocatalytic properties， etc. The relationship between the structure and the properties of LDHs materials has been systematically studied on the level of molecule and electron. This work provides abundant theoretical information and guidance for construc- ting novel LDHs-based functional materials.



Recent Advances of Exosomes Bioanalysis and Their Clinic Applications

ZHANG Yimeng, ZHANG Huixin, LIU Yang

2020, 41(11):  2306-2323.  doi:10.7503/cjcu20200408

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Exosomes are extracellular vesicles with various pivotal bioactive molecules such as lipids， proteins and nucleic acids. They are secreted by all types of cells and distributed in all biofluids， e.g. blood， saliva， sweat and urine. More importantly， the exosomes participate in multiple physiological activities including intercellular communication， mammalian reproduction and immune responses， and play the important role in the pathological progression including the metabolic and cardiovascular diseases， neurodegeneration and cancer， which make them the attractive natural non-invasive biomarkers， and are considered to be potential tools for the clinical diagnosis and therapy. In this review， we summarize the recent developments of biosensors for the detection of exosomes including series of methods such as fluorescence， electrochemistry， electrogenerated chemiluminescence， surface enhanced Raman spectra， colorimetry and microfluidic analysis. In addition， the clinic applications of exosomes were also described on the clinic diagnostic and diseases therapies. Finally， the challenges on the exosomes analysis as well as the potential researches on the clinic diagnostics and diseases therapies in the future were also discussed.



Structural Modification of Fluorescent Proteins and Their Applications in Biosensing

LI Huiyuan, LEI Chunyang, HUANG Yan, NIE Zhou

2020, 41(11):  2324-2334.  doi:10.7503/cjcu20200405

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Since the discovery of fluorescent proteins， they have played important roles in life science， due to their genetic coding and spontaneous emission of robust fluorescence. With the development of protein engineering technology and organic synthesis， and a better understanding of the structure and function of fluorescent proteins， structural modifications and designs of fluorescent proteins were performed to give them new properties and functions， and broaden their applications in biological field such as bioimaging and biosensing. This paper focuses on the progress of the structural modification of green fluorescent protein（GFP）， as well as its mimics， including mutagenesis， barrel structure reconstruction， surface reconstruction， and nucleic acid mimics of fluorescent proteins. The representative applications of these fluorescent proteins and mimics in biosensing are also introduced.



Developments of in situ Cryo-electron Tomography for Biological Applications

ZHAO Guanfang, ZOU Tianyi, CHENG Sihang, YU Yang, WANG Huili, WANG Hongda

2020, 41(11):  2335-2344.  doi:10.7503/cjcu20200323

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The study and structural analysis of biological macromolecular complexes are crucial for a comprehensive understanding of their function and biological significance. The cryo-electron microscopy has become the mainstream technology for providing information about the structure and distribution of macromolecules in biology. In addition， the advancement of hardware and software in rencet years has further improved the effectiveness of cryo-electron microscopy， making it more accurate and faster to analyze various biological structures and proteins. However， for biological systems， proteins or macromolecular complexes are in a complex physiological environment， so in situ detection of the 3D biological structures is crucial for biological system and structural biology. As a powerful technology， cryo-electron tomography can rely on the intrinsic contrast of frozen samples to identify the structure of biological macromolecules directly without marking， and can perform 3D imaging with nano-resolution in their native environment. In this review， we summerized the methods of sample preparation and technical aspects relevant for cryo-electron tomography as well as the biological applications from isolated macromolecular complexes to entire cells and tissues.



Deoxyribozymes： Selection， Biosensing and Outlook

TONG Zongxuan, HU Qinqin, GU Hongzhou

2020, 41(11):  2345-2355.  doi:10.7503/cjcu20200397

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In this review， we briefly describe the origin of deoxyribozymes and the selection strategies for the isolation of these deoxyribonucleic acid（DNA） enzymes. We compare deoxyribozymes with ribozymes and protein enzymes. We focus on the recently developed product-capturing and cancelling selection strategies， as well as the metal-ion-specific and particular-biological-sample-sensing ribonucleic acid（RNA）-cleaving deoxyribozymes which have worked as molecular tools in many aspects. In the end， we summarize the challenges for the deoxyribozyme field that need to be tackled down in the future.



Organic Small Molecule Nanoparticles for Phototheranostics

SHAO Wei, LEE Jiyoung, LI Fangyuan, LING Daishun

2020, 41(11):  2356-2382.  doi:10.7503/cjcu20200319

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Cancer is a global public health issue that is severely threatening human health. Efficient diagnostic and therapeutic methods are in great demand. Photosensitizer（PS）-enabled phototheranostics that integrate diagnosis and therapy into a single platform under near-infrared（NIR） laser irradiation is superior to conventional surgery resection and chemotherapy in terms of noninvasiveness， minimal harm to normal tissues， and high spatial selectivity. With the merits of defined and easily-tuned chemical structure， good reproducibility， and excellent biocompatibility， organic small molecule dyes are promising PSs in phototheranostics as compared to their inorganic and polymeric counterparts. We herein summarize the recent advances of organic small molecules， including conventional small molecule dyes， donor-acceptor（D-A） conjugated small molecules， and aggregation-induced emission molecules（AIEgens）， organic small molecule nanoparticles（OSMNs） in phototheranostics. The future challenges and perspectives of OSMNs in phototheranostics are also discussed.



Structure Prediction of Heterojunction Interfaces and the Application of AutoInterface Program

LI Yefei, LIU Zhipan

2020, 41(11):  2383-2392.  doi:10.7503/cjcu20200417

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The interface in heterojunction plays an essential role in the performance of devices. To date， the structure prediction of the heterojunction interface is challenging. This paper introduces the recent theoretical process in this field. By combining the phenomenological theory of martensitic crystallography， graph theory， and stochastic surface walking method， we have developed an approach to predict the structure of the heterojunction.



Advances in CO₂ Hydrogenation to Methanol by Heterogeneous Catalysis

WANG Yanyan, LIU Huizhen, HAN Buxing

2020, 41(11):  2393-2403.  doi:10.7503/cjcu20200427

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In recent years， with the gradually increased content of carbon dioxide in air， the catalytic conversion of CO₂ has attracted broad attention in scientific and industrial community. CO₂ hydrogenation to methanol by heterogeneous catalysis is one of the most important means to realize the utilization of CO₂， which has a promising application prospect. In this review， we outline recent advances in CO₂ hydrogenation to methanol by heterogeneous catalysis and focus on widely studied metal and metal oxide catalysts. Besides， we give a brief introduction to the reaction mechanism. Finally， we provide the challenges and opportunities in this area.



Progress on the Application of Long Persistent Phosphors in Photocatalytic System

SU Gaoming, SHEN Ruichen, TAN Jie, YUAN Quan

2020, 41(11):  2404-2414.  doi:10.7503/cjcu20200411

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Long persistent phosphor is a new and promising luminescent material， which can maintain luminescence after stopping excitation. In the past few years， long persistent phosphors with unique optical properties have been developed and their applications in the field of photocatalysis have been widely studied. Owing to the characteristic of leaving the light source， long persistent luminescence can effectively promote the photocatalytic reaction in the dark environment. Meanwhile， long persistent phosphor has an important position in the long-time catalytic system due to its long luminous life， which makes round-the-clock photocatalysis possible. In brief， long persistent phosphors have been proved to be a new functional material with unprecedented advantages in photocatalysis. In this review， we summarize the latest advances in the application of long persistent phosphors in the degradation of pollutants， sterilization， and efficient hydrogen production.



Construction of a Fe-MOF Based on Carbazole-carboxylate Ligand for CO₂/CH₄ Separation

XIA Yupei, WANG Chenxue, ZHENG Jinyu, LI Na, CHANG Ze, BU Xianhe

2020, 41(11):  2415-2420.  doi:10.7503/cjcu20200460

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A Fe-MOF（metal-organic framework）（1） was synthesized using 4，4′，4″-（9H-carbazole-3，6，9-triyl）-tribenzoic acid（H₃L） and ［Fe₃（μ₃-O）（CH₃COO）₆］ cluster under solvothermal condition. The structure of the ompound 1 was characterized by X-ray crystallography. Compound 1 possessed a 3D framework with a high specific area. The IAST（Ideal Adsorbed Solution Theory） selectivity of compound 1 towards CO₂/CH₄ （volume ratio 0.5∶0.5） is 3.52（273 K） and 3.15（298 K）， respectively. Gas sorption experiments reveal that compound 1 can serve as a candidate for CO₂/CH₄ separation.



Voltage Modulated Electrochemiluminescence for Highly Sensitive Detection

ZHANG Jingjing, JIN Rong, FANG Danjun, JIANG Dechen

2020, 41(11):  2421-2425.  doi:10.7503/cjcu20200351

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A voltage modulated electrochemiluminescent（ECL） method is established for highly sensitive detection. In this new strategy， a small voltage is imposed at a constant voltage that could increase ECL intensity from luminol-hydrogen peroxide by ca. 2 times. This ECL intensity shows a good linear relationship with the concentration of hydrogen peroxide in the range of 1 nmol/L—200 μmol/L with a detection limit of 0.1 nmol/L（S/N=3）. The results exhibit that the voltage modulated ECL could be an effective way to increase ECL intensity， and more importantly， used to study the electrochemical process at the electrode interface.



Monitoring of Peroxynitrite Variation During Liver Injury Adopting a Far Red to Near-infrared Fluorescent Probe with Large Stokes Shift

WU Qian, CHENG Dan, LÜ Yun, YUAN Lin, ZHANG Xiaobing

2020, 41(11):  2426-2434.  doi:10.7503/cjcu20209236

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Liver injury is one of the major problems affecting public health， and has attracted growing attention. It is universally believed that overexpression of peroxynitrite（ONOO^?） plays an important role in the pathogenesis of liver injury and other diseases， and it is closely related to early liver injury. Therefore， in order to understand the role of ONOO^? in the process of liver injury， an analysis method that can achieve high selectivity and real-time detection of ONOO^? is urgently developed. Herein， we present a far red to near-infrared（FR-NIR） fluorescent probe with large Stokes shift to detect the ONOO^? production in vivo during drug induced liver injury（DILI）. Owing to the large Stokes shift， the FR-NIR probe（LSDQ-ONOO^?） can not only reduce the interference of spectral overlap and self-absorption， but also improve the imaging signal-to-noise ratio. High sensitivity（detection limit=25.8 nmol/L） and excellent selectivity ensured that LSDQ-ONOO^? can monitor subtle changes of ONOO^?in vitro and in vivo during DILI.



Visible-light-induced Selective Oxidation of Alcohols

ZHOU Jinlong, LIU Xiaolong, FU Yao

2020, 41(11):  2435-2441.  doi:10.7503/cjcu20190652

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Selective oxidation of alcohols to aldehydes or ketones has been regarded as one of the most important oxidation reactions in the chemical industry. Establishing a green and mild synthesis method is the main purpose of this research. In this work， 2-chloroanthraquinone is used to selectively oxidize primary and secon-dary alcohols to corresponding carbonyl compounds under the driving of visible light， without additional heavy metals and auxiliary additives. Air or oxygen as the oxidant avoids the stoichiometric use of traditional oxidants， reduces waste release and toxicity， and makes the reaction system simple and easy to purify. The results show that the reaction has a moderate to excellent conversion and selectivity， and is suitable for a series of substrates， providing a new economic， environmentally friendly and sustainable way for the synthesis of benzyl oxygenates.



Inorganic Chemistry

Study on Crystallization Process of SAPO-5 Molecular Sieve

LUO Dongxia, LI Bing, WANG Quanyi, TIAN Peng, LIU Zhongyi, LIU Zhongmin

2020, 41(11):  2442-2448.  doi:10.7503/cjcu20200347

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The crystallization process of SAPO-5 molecular sieve（AFI type） was studied by X-ray diffraction， X-ray fluorescence spectroscopy， scanning electron microscopy and solid-state MAS NMR. The results show that the formation of SAPO-5 molecular sieve follows a liquid-mediated mechanism. In the early stage of crystallization， amorphous aluminophosphate particles with relatively regular morphology（named substance Am） were first formed. SAPO-5 began to appear after the crystallization temperature reached 200 ℃， and the amount of amorphous substance Am also increased significantly. Subsequently， substance Am gradually dissolved and contributed to the growth of SAPO-5. The Si atoms directly participated in the formation of SAPO-5 framework since the early stage of crystallization. As the crystallization proceeded， the Si content in the mole-cular sieve crystals gradually increases. The SAPO-5 framework can only accommodate a small amount of Si（4Al） species， and the Si islands started to appear at low Si content. XPS analysis further revealed that SAPO-5 molecular sieve has surface Si enrichment phenomenon， implying that the Si content in the crystal increases from the core to the shell. The topology of the molecular sieve and the choice of Si source affect the degree of Si enrichment on the crystal surface.



Influence Mechanism of Particle Size and Distribution of Silica Sol in the Synthesis of Ferrierite Zeolite with High SiO₂/Al₂O₃ Ratio

DONG Le, HUANG Xingliang, REN Junjie, DAI Xiaoping, LIU Zongyan, TIAN Hongfeng, WANG Zhidong, WU Xiaotong

2020, 41(11):  2449-2456.  doi:10.7503/cjcu20200289

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Silica sol mother liquids with different particle sizes and distributions were prepared by pre- treating silica sol in solutions of different alkalinities， and then they were used as silicon source to synthesize high-silica ferrierite（FER） zeolites. Mother liquids and products were characterized by means of laser particle size analyzer（LPSA）， Fourier transform infrared spectroscopy（FTIR）， X-ray diffraction（XRD）， scanning electron microscopy/energy dispersive X-ray spectroscopy（SEM-EDS） and X-ray fluorescence（XRF） spectroscopy. The influences of alkalinity on the particle size characteristics of silica sol mother liquid， the crystallization process， and products were investigated. Results indicated that the particle size of the silica sol mother liquid gradually increased with the alkalinity， corresponding to the transition of more Q³ silicon units to Q² silicon units in the solution. At low alkalinity， Q³ silicon units with a high degree of polymerization tended to make crystallization follow the solid-phase transformation mechanism to synthesize pure phase big ferrierite crystals with high yield and relative crystallinity； while at high alkalinity， a large number of active Q² silicon units tended to make the gel coagulate with each other， and the crystallization process followed the liquid-phase transformation mechanism， affording small product with low purity and yield.



Organic Chemistry

Acid-promoted ［5+1］ Annulation of 2-Vinylanilines with Diazo Compounds to 2-Arylquinolines

NAN Jiang, CHEN Pu, MA Yangmin

2020, 41(11):  2457-2463.  doi:10.7503/cjcu20200340

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An acid-promoted ［5+1］ annulation of 2-vinylanilines with diazo compounds for the synthesis of 2-arylquinolines was developed. The strategy applies cheap and available anilines and diazo compounds as substrates， and generates 24 kinds of 2-arylquinolines in metal-free catalysis with excellent functional group tole-rance in moderate to good yields. This method not only provides an efficient， economical and simple approach for the synthesis of 2-arylquinolines， but also enriches the organic reactions of diazo compounds.



Physical Chemistry

Preparation of High Oxygen Porous Carbon from Walnut Peel and Its Adsorption Properties for Ni²⁺

YU Jianxing, YU Moxin, KUAI Le, ZHU Bowen

2020, 41(11):  2464-2472.  doi:10.7503/cjcu20200449

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The hierarchical biomass carbon（HBC_x） was obtained from walnut green peel，which was first prepared by hydrothermal method， and then activated at different temperatures. The as-made HBC_x was characterized by SEM， FTIR， BET and XPS， and its application for adsorption of high or low concentration Ni²⁺ originated from batteries waste water was investigated. The SEM and BET results show that a large number of macropores（about 2 μm） are uniformly distributed on HBC_x. HBC_x has a hierarchical porous structure. When the activation temperature is 800 ℃， the specific surface area of the obtained HBC₈₀₀ is 94 m²/g with the average pore diameter of 4.07 nm. The results of FTIR and XPS show that the surface of carbon materials is rich in oxygen and nitrogen-containing functional groups， and the oxygen content is as high as 21.24%（molar fraction）， which can be ion exchanged or co-precipitated with Ni²⁺. These groups are beneficial to the adsorption process. The prepared porous carbon has a removal rate of close to 100% for low-concentration Ni²⁺ in the waste liquid， showing excellent adsorption performance.The Langmuir model fits well with the adsorption isotherm of Ni²⁺ on HBC_x， which demonstrated the adsorption is monolayer. The maximum adsorption capacity of Ni²⁺ on HBC₈₀₀ is up to 127.39 mg/g. The quasi-second-order kinetic model can describe the adsorption process better. The adsorption rate is mainly controlled by chemical adsorption. Fixed-bed adsorption result shows that the HBC_x is a promising material which can be used in industry widely.



Fluorescence Resonance Energy Transfer Between Coenzyme NADH and Tryptophan

WANG Mengyu, CAO Simin, LI Haoyang, ZHANG Mengjie, LI Dong, ZHAO Zenan, XU Jianhua

2020, 41(11):  2473-2478.  doi:10.7503/cjcu20200428

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Fluorescence resonance energy transfer（FRET） between coenzyme nicotinamide adenine dinucleotide（NADH） and tryptophan in different environments were investigated by using time correlation single photon counting technique， combined with UV-Vis absorption and steady-state fluorescence spectroscopy. Single tryptophan， bovine serum albumin（BSA） and lactate dehydrogenase（LDH） were mixed with NADH， respectively， and the spectral data indicated that the energy transfer between tryptophan and NADH occurred only when lactate dehydrogenase was mixed with NADH. Pyruvic acid were added to block the FRET channel between lactate dehydrogenase and NADH， it was verified that the presence of protein-NADH binding sites was a prerequisite for FRET between NADH and tryptophan by time-resolved fluorescence spectroscopy and decay-associated spectra（DAS）. Furthermore， the average fluorescence lifetime of tryptophan in lactate dehydrogenase was deceased and it was mainly due to the energy transfer between the tryptophan component with lifetime of τ=7.35 ns and NADH， and the efficiency of energy transfer between NADH and tryptophan was calculated. The results might provide a new idea for further study of the interaction between NADH and proteins.



Photodegradation of Antibiotic in Environmental Water by Graphene Oxide Modulation Bismuth Molybdate Under Visible Light Irradiation

ZHAO Mengxin, MENG Zhe, LI Heping, MA Zongqin, ZHAN Haijuan, LIU Wanyi

2020, 41(11):  2479-2487.  doi:10.7503/cjcu20200423

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Using graphene oxide as an activity modulator of photocatalyst， a bismuth molybdate/graphene oxide（Bi₂MoO₆/GO） heterojunction was synthesized via one-step hydrothermal method. Using Bi₂MoO₆/GO（m_Bi2MoO6/m_GO=100∶1） as photocatalyst， the visible light response was extended to 570 nm and the band gap energy was reduced to 2.56 eV compared to Bi₂MoO₆. The photodegradation activity with high selectivity of the Bi₂MoO₆/GO（100∶1） for quinolones， sulfonamides and tetracyclines antibiotics in the aqueous solution under visible light irradiation， which is improved by 2.1 times compared to Bi₂MoO₆. The enhancement of photodegradation antibiotics performance is due to addition of appropriate GO， the intimate interfacial contact and large contact area between Bi₂MoO₆ nanosheets and GO nanosheets via van der Waals forces. It is help to make full use of the electron conductivity of GO for transferring the photogenerated electrons and separating the photoproduced carriers. The radical trapping experiments show that ?OH is played a significant role in the photodegradation procedure. Finally， according to the oxidation products detected by high performance liquid chromato-graphy-mass spectrometric（HPLC-MS）， similar degradation pathway and degradation products for the enrofloxacin was proposed compared with the different photocatalyst.



Effect of Steric Confinement Dimension on Metal Site Anti-carbon Deposition Ability of Ni-SiO₂ Catalysts in CH₄-CO₂ Reforming

WU Hao, WANG Changzhen, QIU Yuan, TIAN Yani, ZHAO Yongxiang

2020, 41(11):  2488-2495.  doi:10.7503/cjcu20200385

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The sintering and carbon deposition of active sites are the main obstacles for the industrial application of methane reforming over Ni-based catalysts. As for the various improvement approaches， the use of steric geometry limiting structure can effectively limit the sintering and carbon deposition of Ni particles. However， there is still a lack of systematic understanding of their relationships based on the confinement dimension. In this paper， three Ni-SiO₂ catalysts（i.e.， traditional supported Ni/SiO₂， mesoporous Ni/SBA-15 and core-shell Ni@SiO₂） with the same chemical composition but different metal exposure structures were prepared to investigate the influence of different steric limiting dimensions/structures on the metals’ anti-carbon deposition mechanism in CH₄-CO₂ reforming. The results showed that Ni/SiO₂ has little steric limiting effect， thus showing the weakest carbon resistance ability and the worst stability. The Ni/SBA-15 has partial steric limiting effect and its anti-carbon deposition ability is significantly improved， while Ni@SiO₂， which has a complete geometric limiting effect， shows the strongest carbon resistance ability with the optimal stability.



Investigation on the Reaction of o-Aminothiophenol and 2-Iodobenzoyl Chloride Monitored by SERS-HPLC Technique

ZHANG Hui, ZHANG Chenjie, XU Minmin, YUAN Yaxian, YAO Jianlin

2020, 41(11):  2496-2502.  doi:10.7503/cjcu20200379

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Surface enhanced Raman spectroscopy（SERS） has been employed in the structural characterization successfully due to its ultra-high sensitivity. However， it is still remained the significant challenge in the precise interpretation of spectral features for detecting multi-species systems. High performance liquid chromatography（HPLC） has been one of the most efficient techniques for the separation and detection of mixture systems， while the performance of structure analysis is highly desired. Herein， combination of SERS and HPLC can make individual advantages of high sensitivity of SERS and high efficiency in separation of HPLC together. It was extended to on-line monitor catalyst effect on the reaction of o-aminothiophenol（OATP） and 2-iodobenzoyl chloride. It was revealed that two different products were dominated in the absence of catalyst： products 1b｛S-［2-（2-iodobenzamido）phenyl］ 2-iodobenzothioate｝ and 2b｛N，N′-［disulfanediylbis（2， 1-phenylene）］bis-（2-iodobenzamide）｝， while product 3b｛10-（2-iodobenzoyl） dibenzo［b，f］［1，4］ thiazepin-11（10H）-one｝ was synthesized with copper acetate as catalyst. The results demonstrated that the reaction was undergone nucleophilic substitution and sulfur radical self-polymerization without catalyst， and the product 1b was undergone structural change to obtain product 3b with catalyst.



Synthesis of Nitrogen-doped Carbon Nanotubes and the Performance and Mechanism of PMS Activation

YAN Song, ZHANG Chengwu, YUAN Fang, QIN Chuanyu

2020, 41(11):  2503-2510.  doi:10.7503/cjcu20200342

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Using multi-wall carbon nanotubes（MWCNT） as raw materials and melamine as a nitrogen precursor， a nitrogen-doped carbon nanotube（N-CNT-700） with a nitrogen content of about 3.33%（molar fraction） was prepared by high-temperature calcination. N-CNT-700 is a one-dimensional tubular nanomaterial， the de-gradation efficiency of phenol can reach 100%， and the total organic carbon（TOC） removal rate can reach 61.6%， and the activation energy of the system is 35.4 kJ/mol within 60 min in N-CNT-700 activated PMS system. Through electron paramagnetic resonance（EPR） detection， quenching experiment and PMS concentration determination， the degradation mechanism of the system was determined to be free radicals（·OH， SO₄^·-） and non-free radicals， in addition to 9% adsorption removal， in the 91% oxidative degradation， free radicals account for about 49%， ¹O₂ for about 18%， and active intermediates for about 24%. The reactivity of N-CNT-700 decreases as the number of reuses increases， and high temperature treatment can restore its high reactivity. The calcination temperature affects the nitrogen content and types of the material. The reactivity of N-CNT is proportional to the nitrogen content and is closely related to the nitrogen content of graphite.



Synthesis of Nano-sized SAPO-34 via Concentrated Gel Conversion Method and Its CH₄/N₂ Separation Performance

LIU Jiaqi, TANG Xuan, WU Luogang, YANG Jiangfeng, LI Libo, LI Jinping

2020, 41(11):  2511-2518.  doi:10.7503/cjcu20200330

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Nano-sized SAPO-34 molecular sieve with a thickness of ca. 50 nm was synthesized by concentra- ted gel conversion method. The obtained samples were characterized by means of XRD， SEM， ICP as well as N₂ adsorption-desorption isotherms（77 K）. The results show that the synthesized nano-sized SAPO-34 has higher specific surface area（818.68 m²/g） and pore volume（0.57 cm³/g） compared with the micron cubic SAPO-34（2 μm）. With higher specific surface and pore volume， the adsorption capacity of CH₄ on the nano-sized SAPO-34 is greatly increased（60%）， reaching 25.74 cm³/g， which is higher than most of the commercial zeolite adsorbents. At the same time， the adsorption selectivity of CH₄/N₂ is not significantly decreased（3.1）， and reaches the level of commercial adsorbents（>3.0）. Through CH₄/N₂（volume ratio 1∶1） mixture gas breakthrough test， it is proved that the synthesized nano SAPO-34 is indeed an effective CH₄/N₂ separation adsorbent and has great potential in the industrial application of coalbed methane enrichment and denitrification.



Stimuli-responsive Fe₃O₄ Nanoparticle Modified by Conjugated Linoleic Acid

ZHANG Xinyu, WANG Hong, FANG Yun, FAN Ye

2020, 41(11):  2519-2525.  doi:10.7503/cjcu20200309

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The surface of Fe₃O₄ nanoparticles was modified by small dosage of the natural unsaturated fatty acid， conjugated linoleic acid（CLA）， instead of oleic acid to prevent the nanoparticles from secondary agglo-meration， oxidization and thus loss of magnetism， and to further improve thermal instability of the modified fatty acid layer. The stability of the modified layer was enhanced by means of self-crosslinking of conjugated double bond of CLA molecules， by which the modified particles could be responsive to the pH stimulus besides the magnetic stimulus. The size and morphology of the modified Fe₃O₄ NPs was imaged by TEM， the coordinationmodes by ATR-FTIR， the dosage of CLA by TG， the surface wettability by θ angle analysis， moreover the droplet size and size distribution of Pickering emulsion stabilized by the modified particles were photographed by large-depth-of-field microscope. The experimental results indicated that the modified particles are well- dispersed relying on a thin and stable， hydrophobic surface showing obvious dual pH/magnetic responsiveness. Pickering emulsion could be stabilized by small dosage of the modified particles（mass fraction 0.05%） and shown the emulsion characteristics of high internal oil phase（oil volume fraction 80%）， switchable by a pH trigger， and migratable in an external magnetic field. A simulation experiment shows that the emulsion can effectively extract and separate organic pollutant in the aqueous phase.



Study on the Photocatalytic Performance of Carbon Doped g-C₃N₄ Based on in situ Photomicrocalorimeter-fluorescence Spectrometry

MA Xiangying, LIAO Yanjun, QIN Fanghong, YIN Yuanhao, HUANG Zaiyin, CHEN Qifeng

2020, 41(11):  2526-2537.  doi:10.7503/cjcu20200292

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Carbon-doped graphite nitride（g-C₃N₄） was synthesized by adding tannic acid to urea precursor. X-ray photoelectron spectroscopy（XPS）， field emission scanning electron microscopy（FESEM）， X-ray diffractometer（XRD）， synchronous thermal analysis（TG-DSC） and other methods were used to characterize the morphology phase and valence components of carbon doped g-C₃N_4. The photocatalytic degradation mechanism of Rhodamine B was investigated by using UV-Vis and in situ photomicrocalorimeter-fluorescence spectrometry to obtain in situ thermodynamics/kinetic information and 3D fluorescence spectral information of the degradation of Rhodamine B by carbon doped g-C₃N₄.The results showed that， when the tannic acid concentration was ≤10 mg/mL， the carbon would replace nitrogen atoms in the unit structure of heptazine to form g-C₃N₄ skeleton carbon doping. When the tannic acid concentration is ≥20 mg/mL， the carbon deposition load on the surface of g-C₃N₄ in amorphous form forms amorphous carbon doping . The skeleton carbon doped g-C₃N₄ to form π electrons effectively shorted the band gap width and reduced the photoelectron-hole recombination probability， showing excellent photocatalytic performance. The main active species of catalysis were h⁺ and ·O{}_{\mathrm{2}}^{-}. The photocatalytic degradation process of carbon doped g-C₃N₄ can be divided into three processes： endothermic of light responds， the balance process of endothermic of light responds and exothermic of pollutant degradation， and stable exothermic. The intensity of fluorescence emission peak of Rhodamine B over skeleton carbon doped g-C₃N₄（C/N=0.844） decreased sharply within the illumination of 1000 s， its degradation rate reached 87.6%，which was 3.13 times and 1.95 times over original g-C₃N₄ and amorphous carbon doped g-C₃N₄， respectively. After illumination of 1000 s， the photodegradation of the ring and intermediates without fluorescent chromophores were dominated， which maintained a stable exothermic rate of （0.9799±0.5356） μJ/s with a pseudo-zero order process. This process was the rate-determining step. Therefore， Rhodamine B photocatalysis was a pseudo-zero-order process rather than a first order process．



Polymer Chemistry

Reversible Regulation of Droplet Directional/anti-directional Rolling on Superhydrophobic Shape Memory Microarray Surface

WANG Wu, LAI Hua, CHENG Zhongjun, LIU Yuyan

2020, 41(11):  2538-2544.  doi:10.7503/cjcu20200485

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Superhydrophobic shape memory microarray with upright structure was fabricated by 3D printing， template molding and surface modification. The upright and tilted structure of the microarray can be controlled reversibly based on the polymer’s shape memory ability. With the change of microarray structure， the rolling state of droplets on the microarray surface can also be changed. The droplet shows anti-directional transport on the upright microarray， that is， the rolling angle of droplet moving toward both sides of the array is consistent. However， on the tilted microarray， the droplet shows directional sliding， that is， the rolling angle of the droplet along the bending direction of the array is smaller than that against the bending direction of the microarray. Therefore， the microarray achieves reversible regulation of droplet directional/anti-directional rolling.



Controllable Synthesis of Amphiphilic Block Copolymer PMnEOS-b-PAA and co-Assembly Morphologies of PMDEOS-b-PAA/PS-b-PAA

SHI Xiaoyu, WANG Songmeng, LIU Lingyan, CHANG Weixing, LI Jing

2020, 41(11):  2545-2552.  doi:10.7503/cjcu20200387

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The co-assembly of polymers has attracted increasing attention due to the ability of generating diverse assembly morphology. This paper describes the synthesis and self-assembly of several novel amphiphilic block copolymers（PMnEOS-b-PAA， n=1—3） as well as co-assembly of PMDEOS-b-PAA with typical polystyrene-b-polyacrylic acid（PS-b-PAA）. Namely， these block copolymers were fabricated by reversible addition fragmentation chain transfer（RAFT） polymerization of functionalized styrene bearing different glycol units on the para-position and acrylic acid， and characterized by ¹H nuclear magnetic resonance spectrum（¹H NMR）. The thermo-responsive and pH-responsive properties of these block copolymers were then investigated， and they showed good thermo- and pH- responsiveness. Furthermore， as a comparison， the self-assembly actions of these block copolymers were also examined in tetrahydrofuran（THF）/H₂O and THF/toluene（PhMe）， respectively. It was found that the different block copolymers with different glycol units displayed various morphologies， especially in two different solvent systems. More interestingly， the co-assembly action of PMDEOS-b-PAA/PS-b-PAA（mass ratio 1∶1） in a mixture of THF-PhMe（volume ratio 2∶1） was detaily studied and a new spherical nanoparticle with uniformly distributed internal channel and smooth surface was found. Also， thisco-assembly morphology could be well repeated. The corresponding self- and co-assembly mechanisms were also proposed. This novel co-assembly mode would have potential application for further supporting catalysts， small molecules recognition and release in industry.



Surface Modified Aramid Pulp with Polyaniline and Conductivity of Its Paper-based Materials

LING Xuxia, LONG Zhu, WANG Shihua, LI Zhiqiang, GUO Shuai, ZHANG Dan

2020, 41(11):  2553-2560.  doi:10.7503/cjcu20200317

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PANI-AP was prepared by modifying polyaniline（PANI） on the surface of aramid pulp（AP）， and then blended with carbon fiber to prepare paper-based material（PANI-AP/CP） with excellent electrical conductivity by wet papermaking technology. The morphology， conductivity and PANI distribution uniformity of PANI-AP/CP were characterized， and the effects of environmental humidity， temperature， pH， and storage time on the electrical conductivity of PANI-AP/CP were explored. The results showed that after PANI modification， the surface roughness and crystallinity of AP increased， and the appearance of diffraction peaks of conductive polyaniline containing quinone structure showed that polyaniline was successfully modified on aramid pulp. For the PANI-AP/CP prepared by this method， both the properties and the distribution uniformity were improved. Compared with the carbon fiber paper substrate （CP） and the AP/CP-PANI， the conductivity of PANI-AP/CP（3.937 S/cm） increased by 153.5% and 34.6%， respectively， and the average total color difference（DE） was reduced by 74.9% compared with AP/CP-PANI.