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10 October 2019, Volume 40 Issue 10

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Cover and Content of Chemical Journal of Chinese Universities Vol.40 No.10(2019)

2019, 40(10):  0-0. 

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Articles:Inorganic Chemistry

Synthesis and Catalytic Performance of Pd/PdO Nanocomposite Microspheres ^†

MA Qinghai,CUI Fang,LIU Mufei,XU linxu,ZHANG Jiajia,CUI Tieyu

2019, 40(10):  2041-2045.  doi:10.7503/cjcu20190283

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Zn(MAA)₂ was introduced to accelerate the reduction of Pd ²⁺ into Pd in PdCl₂ solution. The final sample Pd/PdO nanocomposite microspheres were prepared through calcination. Furthermore, the Pd/PdO nanocomposite microspheres were characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray powder diffraction analysis(XRD) and X-ray photoelectron spectroscopy(XPS). Moreover, UV-visible adsorption spectra were recorded to investigate the performance of Pd/PdO nanocatalysts for the reduction reaction of 4-NTP.



One-step Preparation and Characterization of Broccoli-like Calcium Carbonate ^†

SONG Yunchao,ZHAO Lina,ZHAO Fangwei,CAO Yang,WANG Jiku

2019, 40(10):  2046-2051.  doi:10.7503/cjcu20190291

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Strontium nitrate as an additive was added in the system to prepare uniform distributed broccoli-like calcium carbonate particles. The one-step synthetic method was used which is safe and environment-friendly. The resulting calcium carbonate was characterized through scanning electron microscope(SEM), X-ray diffraction(XRD) and energy dispersive X-ray analysis(EDAX). Meanwile, the possible reaction mechanism of calcium carbonate was put forward.



Synthesis, Structure and Electrochemical Properties of Sulfonylcalix[4]arene Supported Co₁₆ Cluster ^†

ZHANG Min, CHEN Mengwei, GAO Hong, BI Yanfeng

2019, 40(10):  2052-2058.  doi:10.7503/cjcu20190236

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A new sulfonylcalix[4]arene-supported tetrahedral Co₁₆ cage cluster [Co₁₆(TC4A-SO₂)₄(OH)₄·(L)₈][(C₈H₂₀N)(C₄H₁₂N)₂(C₂H₈N)]·solvent(Abbr. Co₁₆-TC4A-SO₂) was synthesized from CoCl₂·6H₂O, p-tert-butylsulfonylcalix[4]arene(H₄TC4A-SO₂) and asymmetric 3-(1H-tetrazol-5-yl)benzoic acid(H₂L) under solvothermal condition. The complex was characterized by single crystal X-ray diffraction(XRD), powder X-ray diffraction(PXRD), thermogravimetric analysis(TGA), and infrared spectroscopy(FTIR). Directly loading Co₁₆-TC4A-SO₂ onto carbon paper(Co₁₆-TC4A-SO₂/CP) as a working electrode exhibited efficient oxygen evolution reaction(OER) catalytic performance. In 1 mol/L KOH, Co₁₆-TC4A-SO₂/CP gained a current density of 10.0 mA/cm ² at a catalytic reaction overpotential of 343.8 mV, a Tafel slope of 79.31 mV/dec, and catalytic stability for 48 h at 20.0 mA/cm ².



Preparation of Large-size Single Layer MXene with Low Defect and Electromagnetic Shielding Performance of MXene Film ^†

LÜ Tong,ZHANG Enshuang,YUAN Yin,FAN Zhimin,MA Xiangyu,CHENG Zhongjun,LIU Yuyan,GONG Yuanxun,ZHAO Hongjie

2019, 40(10):  2059-2066.  doi:10.7503/cjcu20190207

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MXene is a novel two-dimensional material with good hydrophilic surface and superior metallic conductivity. However, high quality MXene with large area, single layer and low-defect is still difficult to be prepared thus far. In this paper, single layer MXene with large area and low-defect was prepared by in situ HF etching Ti₃AlC₂. The microstructures of MXene were characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM), atomic force microscopy(AFM) and so on. The results show that the size of MXene flakes reaches a few microns and the thickness of flakes is only 1.6 nm; no particle oxidation can be found around flakes. The MXene films were prepared by filtering MXene aqueous solution. The MXene films have the characteristics of high conductivity and outstanding toughness. The conductivity of MXene films is as high as 3280 S/cm. By testing the electromagnetic interference shielding performance of MXene films, the electromagnetic interference shielding effectiveness of the material can reach as high as 60.6 dB with 8 μm thickness and the SSE/t value is up to 19531.1 dB·cm ²·g ^-1. In addition, after analyzing the electromagne-tic shielding mechanism of MXene film, we know that it follows an absorption-dominant electromagnetic interference shielding mechanism.



Facile Synthesis of Fe₃O₄@Au Core-shell Nanocomposites as an SERS Substrate for the Detection of Thiram ^†

HAN Donglai,LI Boxun,YANG Shuo,YAN Yongsheng,YANG Lili,LIU Yang,LI Chunxiang

2019, 40(10):  2067-2074.  doi:10.7503/cjcu20190183

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Fe₃O₄ nanomaterial was prepared by thermal decomposition method, and then Fe₃O₄-Au core-satellite nanocomposites and Fe₃O₄@Au core-shell nanocomposites were prepared by seed deposition method and seed-mediated growth method, respectively. The morphology of the Fe₃O₄-Au core-satellite nanocompo-sites and Fe₃O₄@Au core-shell nanocomposites were uniform and the Au nanoparticles were uniformly deposited/coated on the surface of Fe₃O₄ nanomaterials. The samples had good magnetic responsiveness. Using 4-aminothiophenol(4-ATP) as Raman probe molecule, the Raman signal enhancement effect of the two nanocomposites as SERS substrates was compared. The results showed that the Fe₃O₄@Au core-shell nanocompo-site was a better SERS substrate, and had good signal reproducibility. Finally, using Fe₃O₄@Au core-shell nanocomposite as SERS substrate, the SERS signal of the residual thiram was detected on the apple peel successfully.



Analytical Chemistry

One-step Method for Fabrication of Closed Wireless Nanopore Electrode and Its Application on Single Nanoparticle Detection ^†

XU Suwen,YING Yilun,LONG Yitao

2019, 40(10):  2075-2080.  doi:10.7503/cjcu20190339

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We developed a one-step method based on the chemical reduction of HAuCl₄ to fabricate a closed wireless nanoelectrode(CWNE) which provides a high reproducibility in both electrode size and signal-to-noise ratio. By studing the reactant concentration, the successful ratio for fabricating 30 nm CWNE is increased to 85.7% and RMS noise value is decreased to 4.2 pA. Furthermore, the CWNE was applied in the single nanoparticle collision detection which shows a high current resolution at picoampere level and a high temporal resolution at microsecond level. Therefore, the CWNE could be further benefit to achieve the accurate nano-electrochemical measurements.



Antioxidant Capacity Evaluation for Traditional Chinese Herbal Medicines Based on Sensitive g-C₃N₄/P25 Nanocomposite Photoelectrochemical Platform ^†

LIANG Zhishan, NI Shuang, DAI Mengjiao, HAN Fangjie, HAN Lipeng, NIU Li, HAN Dongxue

2019, 40(10):  2081-2089.  doi:10.7503/cjcu20190333

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Chinese herbal medicines are rich in resources and can be found in various types. The efficacy of some Chinese herbal medicines are closely related to their antioxidant effects. Therefore, the rapid and accurate evaluation of the antioxidant capacity is the foundation for the scientific utilization of Chinese herbal medicine resources. By replacing the conventional titanium dioxide(TiO₂) nanomaterials with the P25(the 25 nm anatase and rutile mixed phase titanium dioxide material), the graphitic carbon nitride(g-C₃N₄)/P25 nanocomposite-based sensitive visible light photoelectrochemical platform has been reported herein. In this system, not only the large planar of g-C₃N₄ can serve as a highly-dispersed carrier for the TiO₂ nanomaterials, but also its highly efficient carrier transport capability can endow the composite material with excellent photoelectronchemical performance. The sensitization effect of g-C₃N₄ with a mass ratio of only 0.5% is the best, and the photocurrent response signal of the composite material can be increased by 4.5-fold when compared with the conventional TiO₂ nanomaterials. A good photoelectrochemical signal response can still be obtained under the open circuit potential, which provides a research basis for the construction of the two-electrode system. In comparison with previous reports, the photoelectrochemical strategy not only greatly simplifies the preparation process and reduces the cost, but also effectively improves the visible light utilization efficiency. This method was used for the first time to evaluate the antioxidant capacity of traditional Chinese herbal medicines which provided a new avenue for quantifying the antioxidant performance evaluation of traditional Chinese herbal medicines.



MoS₂-Gold Nanoparticles and Thionine-gold Nanoparticle Based Signal-enhanced Electrochemical Aptasensor for the Detection of 17β-Estradiol ^†

HE Caimei,ZHENG Jingyi,LI Xiaoxia

2019, 40(10):  2090-2096.  doi:10.7503/cjcu20190199

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An ultrasensitive electrochemical aptasensor for the determination of 17β-estradiol(E2) was constructed based on signal-enhanced with molybdenum disulfide nanosheet(MoS₂)-gold nanoparticles(GNPs) and thionine-gold nanoparticle(THI/GNPs) conjugates as electrochemical indicator. The aptasensor was fabricated in sequence by self-assembling of thiolated aptamer DNA probes onto the surfaces of the modified electrodes, and then hybridized with thiolated complementary strand DNA(csDNA) to form double-stranded DNA(dsDNA) duplex. MoS₂-GNPs nanoparticles were used to increase the electrode surface area, enhance the electron transfer rate and amplify the sensor signal. GNPs as a biomarker load thionine, implements the electrochemical indicator signal amplification. E2 can be detected in the concentration range from 1.0×10 ^-14 mol/L to 5.0×10 ^-12 mol/L, and down to levels as low as 4.2×10 ^-15 mol/L. This study may offer a new approach with good analytical properties and potential applications.

Organix Chemistry

Synthesis and Antitumor Activity of Auranofin Derivatives ^†

ZHANG Peiquan,YANG Qianqian,LONG Huidan,CHEN Xin

2019, 40(10):  2097-2103.  doi:10.7503/cjcu20190246

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A new type of auranofin derivatives was synthesized and characterized by means of nuclear magne-tic resonance spectroscopy(NMR) and high resolution mass spectroscopy(HRMS). After treatment of tumor cells with target compounds, the effect of the target compound on cell viability was determined by MTS assay, apoptosis was detected by flow cytometry, Western blot was used to detect the effects of target compounds on total ubiquitinated protein(Ub-Prs), K48-linked polyubiquitinated protein and the expression of protease-specific substrate(GFPu) in vitro. The results showed that the auranofin derivative exerted a better antitumor effect by inhibiting the function of the proteasome.

Synthesis of Chiral 3-Substituted Benzoquinone Compounds Through Asymmetric Catalytic Tandem Reaction with Chiral Phosphoramide as Catalyst ^†

GUO Qingjun

2019, 40(10):  2104-2110.  doi:10.7503/cjcu20190234

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We used thiophosphoramide as a catalyst, which was synthesized after several simple reactions of trans-1,2-diphenyl-ethylenediamine, aromatic aldehydes and arylalkyl zincs or diethylzinc as reactants, to synthesize chiral 3-substituted benzoquinone compounds with important biological activity, through 1,2-addition/lactoneization tandem reaction. The raw materials are cheap and easy to obtain, the catalytic efficiency is high. The yield and e.e. value can be guaranteed to be as high as 80% simultaneously. Despite the large amount of catalyst, the ligand is very convenient to recycle and reuse in this system. At the same time, we speculate on the reaction mechanism, and believe that the quaternary transition state and the six-element transition state formed by the reaction process are beneficial to improve the enantioselectivity of the reaction.

Synthesis and Anti-tumor Activity Evaluation of a Series of 2- or 4-Substituted Pyrido[3,2-d]pyrimidines as Nonclassical Antifolates ^†

FANG Fang,XUE Liangmin,CONG Jing,TIAN Chao,WANG Xiaowei,LIU Junyi,ZHANG Zhili

2019, 40(10):  2111-2120.  doi:10.7503/cjcu20190108

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Using compounds 2,4-diamino-6-(4-methylphenethyl)pyrido [3,2-d] pyrimidine(wm-5b) and 2,4-diaminopyrido [3,2-d] pyrimidine as the lead compounds, a series of 2- or 4-substituted pyrido[3,2-d]pyrimidines was synthesized as potential nonclassical antifolates by means of microwave efficiently. Besides, the effects of different substituted positions which provides more theoretical basis for the design and synthesis of nonclassical antifolates can be explored. The target compounds were characterized by ¹H NMR, ¹³C NMR as well as MS. All compounds showed certain anti-tumor activity[compound 6b, the most potent one, has IC₅₀ values of (4.09±0.48) μmol/L against HL-60 cells, IC₅₀ value of (17.99±7.20) μmol/L against A549 cells and IC₅₀ value of (14.52±4.74) μmol/L against HCT116 cells], while some of them exhibited certain inhibition of recombinant human DHFR(rhDHFR). Some compounds and the lead were applied to molecular docking of the crystal structure of dihydrofolate reductase, and the activity results and structure-activity relationship were explained at the molecular level.

Physical Chemistry

Density Functional Theory Study of NO, NO₂ Adsorbed on ZnO(10 \overline{1} 0) Surface ^†

YANG Xiurong,ZHANG Chi,GAO Hongxu,ZHAO Fengqi,NIU Shiyao,GUO Zhaoqi,MA Haixia

2019, 40(10):  2121-2127.  doi:10.7503/cjcu20190295

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The Perdew-Burke-Ernzerh(PBE) method of generalized gradient approximation(GGA) in DMol ³ module was used to study the adsorption behavior of gas products NO and NO₂ decomposed by energetic materials(EMs) on ZnO(10 \bar{1} 0) surface and the process of NO₂ dissociation to form NO and O. The optimized adsorption configurations show that the top position of Zn on the surface is a stable adsorption site, and the adsorption energy of NO₂ is larger than that of NO. The analysis of density of states combined with the deformation charge density shows that the N atom of NO interacts with the surface Zn, and the charge transfers from NO to the surface. The N_2p and O_2p orbitals of NO₂ overlaps with the surface Zn_3d orbital, resulting in hybridization and accumulation of a large amount of negative charges near NO₂. The transition state search shows that the dissociation of NO₂ needs to cross the higher energy barrier and is not easy to carry out. This simple adsorption of small molecular gas reveals the mechanism of action on the surface of ZnO and improves the catalysis of nano-ZnO on EMs.



Potential Spin Crossover and Valence Tautomerism of Hetero-nuclear Inverse Sandwiches [M(AIP)](C₅H₅)[M'(AIP)](M, M'=V, Cr, Mn) ^†

LIU Nannan, WANG Jian

2019, 40(10):  2128-2134.  doi:10.7503/cjcu20190280

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The inverse sandwiches [M(AIP)](C₅H₅)[M'(AIP)](M, M'=V, Cr, Mn; AIP=dehydro-genated-1-amino-3-imino-prop-1-ene anion, C₃N₂ {\mathrm{H}}_5^{-} ) were theoretically studied. The calculated results show that V-Cr system has the quintet, septet, and nonet multistable states; and Cr-Mn system has the triplet, quintet and septet multistable states. In these systems, the valence states of metal atoms vary with the spin states of isomers, the variable valence states of +1 and +2 could be observed in V, Cr and Mn atoms. Due to the low spin crossing barriers between some bistable states of V-Cr and Cr-Mn systems, the spin crossover and valence tautomerism become possible. Since [M(AIP)](C₅H₅)[M'(AIP)] not only performs the spin crossover and valence tautomerism, but also has the stability against dissociation, these molecules are potential candidate for molecular magnetic materials.



Theoretical Study of Dry Reforming of Methane Catalyzed by Bimetallic Alloy Cluster M₁₂Ni(M=Pt, Sn, Cu) ^†

CHEN Tao,FANG Lei,LUO Wei,MENG Yue,XUE Jilong,XIA Shengjie,NI Zheming

2019, 40(10):  2135-2142.  doi:10.7503/cjcu20190267

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The electronic activity and structural stability of three bimetallic alloy clusters of M₁₂Ni(M=Pt, Sn, Cu) were studied by density functional theory(DFT). The change of the methane dry reforming reaction(DRM) on three clusters M₁₂Ni(M=Pt, Sn, Cu) was also discussed. It is found that the methane dehydrogenation and carbon dioxide activation process exhibit the lowest activation energy barrier to be overcome on the surface of Pt₁₂Ni cluster, so these two processes are the most potential to carry out over Pt₁₂Ni cluster. The formation of carbon on the Sn₁₂Ni cluster requires higher activation energy, indicating that the Sn₁₂Ni cluster can effectively inhibit the formation of carbon. To some extent, it overcomes the catalyst deactivation caused by carbon deposition. And the Sn₁₂Ni cluster exhibits the best catalytic activity during the oxidation of C ^* and CH ^*. The Cu₁₂Ni cluster shows excellent catalytic activity only during the dehydrogenation of methane.



High-temperature in situ Raman Spectroscopic Study on the Micro-structure of Bi₄B₂O₉ Crystal and Melt ^†

XU Yandong,YOU Jinglin,WANG Jian,GONG Xiaoye,DING Yani,CAO Peiming,ZHENG Shaobo,WU Yongquan,YU Zhongda

2019, 40(10):  2143-2148.  doi:10.7503/cjcu20190260

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Raman spectrum of Bi₄B₂O₉ crystal at ambient temperature was measured and calculated via density functional theory and vibration modes of all the peaks were assigned. Then high temperature in situ Raman spectroscopic technique was utilized to measure Raman spectra of Bi₄B₂O₉ crystal from room temperature to 750 ℃(above the melting point) to investigate its micro-structure’s evolution. With the temperature increasing, the lattice lengthens in bond length and broadens in bond angle. After melting, BiO₄ and BiO₅ polyhedron in crystal tends to convert, while BO₃ triangle stays constant. Ab initio method was used to simulate the microstructure of Bi₄B₂O₉ melt cluster, calculate and analyze its Raman spectra. It is found that B atoms in Bi₄B₂O₉ melt form isolated BO₃ triangle structure and Bi ³⁺ cation among BO₃, connecting O atoms out of BO₃, functions as charge balancer.



Effect of Emulsification Process on the Thermal Properties of Stearic Acid Phase Change Microcapsules ^†

CHEN Yuan,ZHAO Xuejing,LIANG Hongwei,WU Xiuwen,ZHANG Jinlin

2019, 40(10):  2149-2155.  doi:10.7503/cjcu20190253

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Microcapsules were prepared by in situ polymerization using calcium carbonate as wall material and stearic acid as core material. And its surface morphology and thermal properties are characterized by scanning electron microscopy, Fourier transfer-infrared spectrometry, differential thermal analysis and thermogravimetry. The effect of emulsifying process on the surface morphology, transformation temperature and encapsulation rate were studied by changing the kinds and dosage of emulsifiers. The results showed that sodium dodecyl benzene sulfonate is the most suitable emulsifier compared with cetyltrimethylammonium bromide and TX-100, and the adequate mass proportion of the emulsifier vs. core material is 0.5%. The transformation temperature is 112.24 ℃, and the clad ratio is 92.1%.

Preparation of a Sandwich-like Ni-P@Ni-B/Ni Catalytic Electrode for pH-Universal Hydrogen Evolution Reaction ^†

WANG Chenfeng, XU Qiuyu, WANG Lincai, ZHANG Ruiqi, PAN Xinxin, WANG Jingwei, HAO Weiju

2019, 40(10):  2156-2163.  doi:10.7503/cjcu20190251

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A sandwich structure Ni-P@Ni-B/Ni catalytic electrode was prepared by electroless plating. The Ni-P@Ni-B catalytic material has an amorphous spherical structure with a diameter of 1μm. When the current density of Ni-P@Ni-B/Ni is 10 mA/cm ², the overpotential is only 287 mV in 0.5 mol/L phosphate buffer saline(PBS). After operating for 24 h at a overpotential of 287 mV, the current density of Ni-P@Ni-B/Ni only attenuated by 7.6%. At the same time, the Ni-P@Ni-B/Ni electrode also has an excellent catalytic activity for hydrogen evolution reaction both in acidic and alkaline conditions, it achieves a cathodic current density of 10 mA/cm ² at overpotentials of 199 and 79 mV in 0.5 mol/L H₂SO₄ and 1 mol/L KOH, respectively.



Tunable Synthesis of BiOBr for Efficient Photocatalytic Degradation of Carbamazepine in Wastewater ^†

GUO Qian,TANG Guangbei,WANG Hao,SUN Qian,GAO Xiaoya

2019, 40(10):  2164-2169.  doi:10.7503/cjcu20190229

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A series of BiOBr photocatalysts was prepared with different bromine sources using an ethanol mediated solvothermal method with Bi(NO₃)₃·5H₂O as precursor. The obtained samples were characterized by powder X-ray diffraction(XRD), scanning electron microscopy(SEM), Fourier transform Infrared spectroscopy(FTIR), UV-Vis diffuse reflectance spectroscopy(UV-Vis DRS) and N₂ adsorption-desorption analysis. The results showed that the crystallinity structure, morphology and specific surface were influenced by bromine source. The BiOBr(K∶C=3∶7) sample prepared with KBr and CTAB(molar ratio 3∶7) as bromine sources exhibited high photocatalytic efficiency towards the degradation of carbamazepine under simulated solar light irradiation. The photocatalytic reaction with BiOBr(K∶C=3∶7) as catalyst followed pseudo first-order kinetics model with a reaction rate constant over 4.10, and 2.14 times that with BiOBr(K) and BiOBr(C) as catalyst, respectively. The enhanced photocatalytic activities could be attributed to the highly exposed(110) facet, surface hydroxyl, loose-packed lamellar morphology, as well as large specific surface area and pore volume. Radicals trapping experiments showed that h ⁺, ·OH and e ^- were involved in the photocatalytic degradation of carbamazepine.

Effect of Copper Doping on Lean NO_x Trap Performance of Pt/Ba/Cu_xMg_1-xAl₂O₄ Catalysts at High Temperatures ^†

YIN Mengxin,LIU Dongsheng,ZHAO Dongyue,DING Tong,TIAN Ye,LI Xingang

2019, 40(10):  2170-2177.  doi:10.7503/cjcu20190226

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A series of Pt/Ba/Cu_xMg_1-xAl₂O₄ catalysts with Cu doping was synthesized and used in high-temperature NO_x storage reduction reaction. The results demonstrate that BaCO₃, the NO_x storage component, redisperses in the NO_x storage reduction process. Moreover, the De-NO_x activity of the catalysts at high temperatures was determined by the NO_x storage capacity, rather than the NO oxidation and NO_x reduction ability of the catalysts. The NO_x storage capacity of the catalysts is directly linked to the thermal stability of nitrate species stored on the catalysts. NO_x mainly exists in the form of ionic nitrate species on Pt/Ba/MgAl₂O₄, while NO_x mainly co-exists as ionic nitrate and monodentate nitrate species on the Cu-doped catalysts. We discovered that monodentate nitrate species show higher thermal stability than ionic nitrate species. As a result, the Cu-doped catalysts exhibit the larger NO_x storage capacity and hence the higher De-NO_x activity. At the temperature range from 450 ℃ to 500 ℃, the addition of Cu greatly enhanced the NO_x removal percentage of the catalysts. Among all the catalysts, Pt/Ba/Cu_0.1Mg_0.9Al₂O₄ has the highest De-NO_x activity with NO_x removal percentage about 90% at 450 ℃.



Preparation of Protonated g-C₃N₄/β-SiC Composites and Photocatalytic Degradation of Alizarin Red S ^†

WU Zhiqiang, LIU Wanyi, WANG Gang, CAI Wei, YUE Xiaofei, ZHAN Haijuan, BI Shuxian, MENG Zhe, MA Baojun

2019, 40(10):  2178-2185.  doi:10.7503/cjcu20190215

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Graphite phase carbonitride(g-C₃N₄) and silicon carbide(β-SiC) were synthesized by pyrolysis and sol-gel-carbothermic reduction method, respectively. Then, they were combined by the impregnation-heat treatment and protonated by concentrated hydrochloric acid to prepare g-C₃N₄/β-SiC and protonated g-C₃N₄/β-SiC(P-g-C₃N₄/β-SiC) composite photocatalysts. The samples were analyzed by X-ray diffraction(XRD), scanning electron microscopy(SEM), high resolution transmission electron microscopy(HRTEM), Fourier transform infrared spectroscopy(FTIR), X-ray photoelectron spectroscopy(XPS), UV-Vis diffuse reflectance spectroscopy(UV-Vis-DRS) and phototluminescence(PL) characterization. The results show that the P-g-C₃N₄/β-SiC composite did not retain the lamellar morphology and its specific surface area is significantly increased. The UV-Vis-DRS and PL spectra indicate that the recombination probability of photogenerated electron-hole pairs is significantly reduced, and the band gap is significantly improved. At the same time, experiments revealed that the combination of g-C₃N₄ and β-SiC and protonation can have a positive effect on the effective separation of photogenerated electron-hole pairs. In addition, the catalysts were applied to photocataly-tic degradation of alizarin red S(ARS). The results show that the order of visible light photocatalytic activity of the samples is P-g-C₃N₄/β-SiC>g-C₃N₄/β-SiC>P-g-C₃N₄>g-C₃N₄>β-SiC. The degradation efficiency of sample P-g-C₃N₄/β-SiC to ARS was up to 99.9% within 60 min, which accorded with the pseudo first-order kinetic model. The rate constant was 0.0967 min ^-1. After 9 times of cycle, the photocatalytic degradation efficiency of P-g-C₃N₄/β-SiC for ARS remained above 97.5%.

Structure and Properties of Sulfonated Poly(ether ether ketone)/Laponite Proton Exchange Membrane for All Vanadium Redox Flow Battery ^†

LIU Bo,ZOU Nan,ZHANG Yuxia,SHI Haifeng

2019, 40(10):  2186-2194.  doi:10.7503/cjcu20190190

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A series of sulfonated poly(ether ether ketone)/laponite(SPEEK/Lap) composite membranes was prepared by solution-casting method using SPEEK with a sulfonation degree of 58% as membrane matrix. The membrane properties such as water uptake(WU), swelling ratio(SR), proton conductivity(σ), vanadium ion permeability and ion selectivity were detailly characterized and discussed. The results show that the introduced Lap nanofillers effectively improve σ, SR and mechanical properties of SPEEK composite membranes. The tensile strength of the SPEEK/Lap-0.2 composite membrane is 1.64 times that of pure SPEEK membrane. When the mass fraction of Lap increases from 0.2% to 1.5%, σ(19.9—23.6 mS/cm) increases accordingly. The ion selectivity of SPEEK/Lap-0.2 composite membrane is the best(5.55×10 ³ S·min·cm ^-3), which is about 1.39 times that of Nafion 117 membrane(3.99 S·min·cm ^-3). In the single cell test, the self-discharge time of SPEEK/Lap-0.2 composite membrane is 57.2 h, which is 2.4 times that of Nafion 117 and 1.5 times that of pure SPEEK membrane. At a current density of 80 mA/cm ², the voltage efficiency(VE, 86.5%) and energy efficiency(EE, 84.0%) of SPEEK/Lap-0.2 composite membrane are much higher than those of Nafion 117(VE: 83.8%, EE: 80.7%) and SPEEK membrane(VE: 81.4%, EE: 78.9%). During the 100 times charge-discharge test, SPEEK/Lap-0.2 composite membrane exhibits a stable energy efficiency, proving its good structure stability. In addition, SPEEK/Lap composite membranes exhibit a higher chemical stability in harsh oxidizing environment as compared with SPEEK membrane. Laponite nanofillers demonstrate a promising application as the low-cost high proton conductor, which can be used to prepare the proton exchange membrane(PEM) with high ion selectivity and low vanadium ion permeability for vanadium redox flow battery(VRFB) application.

Experimental and Theoretical Analysis of Quinoline Diquaternary Ammonium Salt as Corrosion Inhibitor ^†

DONG Qiuchen,ZHANG Guanghua,ZHANG Wanbin,LIU Jing

2019, 40(10):  2195-2204.  doi:10.7503/cjcu20190181

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Two water-soluble bisquinoline quaternary ammonium salts with hydrophobic structures(BQA-1 and BQA-2) were prepared from quinoline, alpha'-dichloro-p-xylene and cis-1,4-dichloro-2-butene. The corrosion inhibitory property of BQA-1 and BQA-2 on Q235 steel in 1 mol/L hydrochloric acid solution and their adsorption behavior on Q235 steel surface were studied by means of mass loss measurement, electrochemical technique, scanning electron microscopy(SEM) and quantum chemical calculation. The mass loss results show that BQA-1 and BQA-2 had good corrosion inhibition effect on carbon steel in hydrochloric acid, when the mass concentration was 0.5 g/L and the temperature was 30 ℃, the inhibition efficiencies of BQA-1 and BQA-2 were both over 94.59%. In addition, the temperature rise resulted in a faster rate of desorption of BQA-2 than BQA-1. Electrochemical experiment results show that BQA-1 and BQA-2 are mixed type inhibitor and preferentially inhibited the cathodic reaction. Thermodynamic and activation energy parameters show that the adsorption of BQA-1 and BQA-2 on steel surface is spontaneous and exothermic, conforming to the Langmuir’s adsorption isotherm and mainly based on chemical adsorption. Quantum chemical calculation results show that the active sites of BQA-1 and BQA-2 are concentrated on the quinoline rings and heteroatom, and the ability of BQA-1 and BQA-2 molecules to accept electrons is greater than the ability to provide electrons.

Photocatalytic Performance of Fe-complexes Prepared Using Cotton Fiber Modified with Different Dicarboxylic Acids ^†

GAN Lu,DONG Yongchun

2019, 40(10):  2205-2213.  doi:10.7503/cjcu20190187

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Three dicarboxylic acids(DCAs), tartaric acid(TA), malic acid(MA) and succinic acd(SA), were used for the modification of cotton fiber to introduce carboxyl groups, respectively, which then coordinated with Fe ³⁺ ions to prepare the modified cotton fiber Fe complexes, Fe-DCA-Cotton. Effects of cha-racteristic structure and concentration of dicarboxylic acids on carboxyl group content(Q_COOH) of the modified cotton fiber and Fe content(Q_Fe) of the resulting Fe complexes were investigated. The catalytic activities of three Fe-DCA-cotton complexes as photocatalysts for the oxidative degradation of organic dye and Cr(Ⅵ) reduction were evaluated and compared. The results indicated that Q_COOH of the modified cotton fiber increased with concentration of carboxylic acid increasing. SA without hydroxyl group could give cotton fiber more carboxyl groups than the two hydroxyl dicarboxylic acids, TA and MA. However, the Fe complexes prepared with Fe ³⁺ ions and two hydroxyl dicarboxylic acids showed higher Q_Fe values. The three Fe-DCA-cotton complexes exhibited significant photocatalytic performance for the oxidative degradation of organic dye and Cr(Ⅵ) reduction. Increasing Q_Fe and irradiation could enhance their catalytic activity. Fe-TA-cotton complex has a better photocatalytic activity than the two complexes. Besides, the three complexes could not only reduce Cr(Ⅵ) into Cr(Ⅲ) ion, but also partially remove it through adsorption effect. Fe-MA-cotton complex showed relatively high Cr removal efficiency.

Study on Particle Size Effect on Adsorption Thermodynamics and Kinetics of Cubic Nano-Cu₂O ^†

XIAO Biyuan,QIU Jiangyuan,QIN Fanghong,WAN Ting,XU Yaqun,NONG Xiaohui,HUANG Zaiyin

2019, 40(10):  2214-2224.  doi:10.7503/cjcu20190117

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The impacts of particle size and temperature on the adsorption kinetics and thermodynamics of nanomaterials were investigated by using single faceted cubic Cu₂O(100) with different particle sizes as model materials. Based on previously reported theory of adsorption thermodynamics and kinetics of nanomaterials, the relationships between the particle size of the cubic Cu₂O nanoparticles and their adsorption thermodynamics and kinetics were derived. The experimental results are in good agreement with the theoretical predictions. With the decrease of the size of the cubic Cu₂O(100) nanoparticles, the following characteristics were observed: (1) the adsorption rate constant increased, while the adsorption activation energy and the adsorption pre-exponential factors decreased; (2) the standard molar Gibbs free energy of adsorption(Δ_aG ^0— _m) decreased, while the standard equilibrium constant(lnK ^0—), the standard molar enthalpy of adsorption(Δ_aH ^0— _m), and the standard molar entropy of adsorption(Δ_aS ^0— _m) increased. The thermodynamic properties and kinetic parameters above have a good linear relationship with the reciprocal of particle size.

Polymer Chemistry

Preparation and the Antibacterial Activity of AgNPs/PLGA-PEG-PLGA Composite Hydrogel ^†

YUAN Baoming,DONG Xiaoming,YANG Fan,PENG Chuangang,WANG Jincheng,Wu Dankai

2019, 40(10):  2225-2232.  doi:10.7503/cjcu20190351

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The PLGA-PEG-PLGA triblock thermosensitive hydrogel was synthesized via ring opening copolymerization of D,L-lactide(D,L-LA) and glycolide(GA) with PEG1000 as a macromolecular initiator. ¹H NMR spectrum of the copolymer was obtained to confirm the structure and composition. Silver nanoparticles which prepared by reduction of silver nitrate were mixed with the prepared PLGA-PEG-PLGA three block copolymer hydrogel. A new type of AgNPs/PLGA-PEG-PLGA hydrogel was prepared. The properties of AgNPs/PLGA-PEG-PLGA composite hydrogels were characterized. The AgNPs/PLGA-PEG-PLGA composite hydrogel still has a temperature sensitive property, and the sol-gel phase transition occurs with the increase of temperature. Novel hydrogel can be sustained release of silver nanoparticles to play antibacterial properties. In vitro biocompatibility experiments showed that the novel AgNPs/PLGA-PEG-PLGA hydrogel has good biocompatibility and no cytotoxicity. It is a new type of composite hydrogel with good application prospect.



Design and Synthesis of Novel Iodinated Polycarbonates with Inherent X-Ray Opacity ^†

MA Qian,WU Xiaohui,YU Lin,DING Jiandong

2019, 40(10):  2233-2240.  doi:10.7503/cjcu20190231

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Biodegradable polymeric materials with X-ray opacity are unique in various biomedical studies in vivo, yet the available polymers, in particular functionalized monomers, are very limited. Herein, a novel iodinated cyclic carbonate monomer, 4-iodo-N-(2-oxo-1,3-dioxan-5-yl)benzamide(IBTMC), was designed and synthesized by amidation and subsequent intramolecular cyclization using 2-amino-1,3-propanediol, 4-iodobenzoyl chloride and ethyl chloroformate as raw materials. Then, a series of iodinated polycarbonates with inherent X-ray opacity were obtained via ring-opening copolymerization of IBTMC and trimethylene cyclic carbonate(TMC) using 1,5,7-triazabicyclo[4.4.0]dec-5-ene(TBD) as the catalyst. Their chemical structures and compositions, molar mass dispersity, thermal properties and radiopacity were characterized via proton nuclear magnetic resonance( ¹H NMR), gel permeation chromatography(GPC), differential scanning calorimetry(DSC), thermogravimetric analysis(TGA) and micro-computed tomography(Micro-CT). The results illustrated that the iodinated polycarbonates had good thermal stability and outstanding X-ray opacity. Finally, a subcutaneous implantation experiment in ICR mice demonstrated the potential of the synthesized iodinated polycarbonates for in vivo deep tissue imaging.



Monte Carlo Simulation on the Semi-batch Process in the Self-condensing Vinyl Polymerization System in the Presence of Core Initiators ^†

WANG Qianqian,YIN Luping,GU Fang,WANG Haijun

2019, 40(10):  2241-2247.  doi:10.7503/cjcu20190221

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The semi-batch process of the self-condensing vinyl polymerization in the presence of core initiators was investigated by the method of Monte Carlo simulation. An attempt was made to find the influence of diffe-rent feeding ways on the weight-average molecular weight and polydispersity index of the resultant polymers. Specifically, we presented several semi-batch modes, such as the case that core initiators are fed into the reactor at distinct conversions, and different feeding ways together with their details concerning the added molecules and conversions. Consequently, a significant effect of the semi-batch process on the present system was found, which is expected to be useful in the large-scale production of hyperbranched polymers.



Fabrication of PVDF Hybrid Blending Membrane via Microemulsion Polymerization Coupling with Blending Method ^†

LIU Zihao,XIAO Han,YAO Yuan,WANG Ting,WU Liguang,ZHANG Xueyang

2019, 40(10):  2248-2256.  doi:10.7503/cjcu20190189

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AgCl nanoparticles were obtained in the reverse microemulsion using styrene and methyl methacrylate mixture as an oil phase. And then, polymer emulsion containing AgCl nanoparticles was obtained through in-situ polymerization of oil monomers in the microemulsion. Finally, polyvinylidene fluoride(PVDF) blending hybrid membranes containing AgCl nanoparticles were constructed by blending method. The results from the structural characterization and ultrafiltration experiments, such as UV-visible spectroscopy, transmission electron microscopy(TEM), and scanning electron microscopy(SEM), showed that the addition of some polymer emulsion combined with hydrophilic polymer and AgCl nanoparticles with hydrophilic surface did not only improve the porosity and average pore size of the PVDF blending hybrid membranes, but also enhanced the polarity and hydrophilicity of the hybrid membranes, thus increasing the water flux and antifouling performance of the membranes. However, the addition of excess polymer emulsion could not blend uniformly with PVDF. Moreover, AgCl nanoparticles would form agglomerates in the membrane to clog the membrane pores. Thereby, the water flux and antifouling performance of the membranes were both weakened.