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2019, Vol. 32, No. 5　Online: 2019-05-15


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Probing the intrinsic catalytic activity of carbon nanotubes for the metal-free oxidation of aromatic thiophene compounds in ionic liquids (Pages 131-137)
Nanocarbon-based catalysts represented an area of increasing interest in recent years. They have been proved to be efficient catalysts for enormous catalytic processes including thermal catalysis, photocatalysis and electrocatalysis. The unambiguous mechanistic understandings (e.g., active sites) and the relatively low activity are major obstacles for the development of carbocatalysis. In this paper, we focused on these two aspects. A detailed study of the reaction process with a temperature-programmed treatment of the oCNTs combined with a series of control experiments of chemical deactivation and model catalysts experiments reveals that carbonyl groups are the active sites of oCNTs for the dibenzothiophene (DBT) oxidation reaction. Besides, by introducing PF₆^- anion based ionic liquids (ILs), the catalytic activity of oCNTs for the oxidation of DBT effectively could be enhanced dramatically. As clarified by EPR and H₂O₂ self-decomposition experiments, the PF₆^- anion based ILs could protect HO·radicals from forming O₂ and also in favor of forming carbon involved intermediates, thus could improve the catalytic performance of the nanocarbon/ILs combined catalytic system. This is the first time that the nanocarbon/ILs combined catalytic system is proposed and it is promising for different catalytic applications with the low-cost carbon materials as catalysts.

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An insight into failure mechanism of NASICON-structured Na3V2(PO4)3 in hybrid aqueous rechargeable battery Xinxin Zhang, Jun Ma, Pu Hu, Bingbing Chen, Chenglong Lu, Xinhong Zhou, Pengxian Han, Lihua Chen, Guanglei Cui 2019, 28(5): 1-7.  DOI: 10.1016/j.jechem.2018.05.016 摘要 ( 205 )   NASICON (Na-super-ionic-conductors)-structured materials have attracted extensive research interest due to their great application potential in secondary batteries. However, the mechanism of capacity fading for NASICON-structured electrode materials has been rarely studied. In this paper, we synthesized the NASICON-structured Na3V2(PO4)3/C composite by simple sol-gel and high-temperature solid-phase method and investigated its electrochemical performance in Na-Zn hybrid aqueous rechargeable batteries. After characterizing the structure, morphology and composition variations as well as the interfacial resistance changes of Na3V2(PO4)3/C cathode during cycling, we propose a mechanical and interfacial degradation mechanism for capacity fading of NASICON-structured Na3V2(PO4)3/C in Na-Zn hybrid aqueous rechargeable batteries. This work will shed light on enhancing the mechanical and interfacial stability of NASICON-structured Na3V2(PO4)3/C in Na-Zn hybrid aqueous rechargeable batteries.

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Adsorption desulfurization of model gasoline by metal-organic framework Ni3(BTC)2 Fuping Tian, Qiaofeng Ru, Chenxia Qiao, Xin Sun, Cuiying Jia, Yu Wang, Yifu Zhang 2019, 28(5): 8-14.  DOI: 10.1016/j.jechem.2018.06.006 摘要 ( 236 )   This work presented the synthesis of Ni-based metal-organic framework material with a paddle-wheel structure Ni3(BTC)2 (Ni-BTC) and its application in thiophene (TP) adsorption from gasoline distillate by batch method. Adsorption isotherms of TP, cyclohexene, and toluene in cyclohexane onto Ni-BTC were conducted at 298-308 K to interpret the different effect of cyclohexene and toluene on TP adsorption. The results showed that, compared with cyclohexene, toluene addition in model gasoline led to a more evident decline in sulfur capacity of Ni-BTC, which is opposite to isostructural HKUST-1. The adsorption isotherms of TP, cyclohexene and toluene fit Langmuir model, S-type model and Temkin model well, respectively, indicating that the adsorption mechanisms of TP and the two competitors are different from one another. The adsorption capacities on Ni-BTC followed the order of cyclohexene < toluene < TP at the same equilibrium concentrations, implying the order of the adsorption affinities, which is in good agreement with the different extent of influence by the two competitors. The enthalpy of TP adsorption on Ni-BTC was estimated to be -80.01 kJ/mol, almost twice that on HKUST-1. The poor reusability of Ni-BTC in batch experiment, which is owing to its sensitivity to the air, can be prevented from regenerating used Ni-BTC in fixed-bed reactor by N2 flow. The difference between Ni-BTC and HKUST-1 in maximum adsorption capacity (q0), △H of TP adsorption, and stability demonstrates that the central metal in isostructural MOFs plays a key role in adjusting the desulfurization performance, which may open up a potential avenue for the development of MOF-based adsorbents with superior desulfurization performance.

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Recent advances on flexible electrodes for Na-ion batteries and Li-S batteries Mohammed-Ibrahim Jamesh 2019, 28(5): 15-44.  DOI: 10.1016/j.jechem.2018.06.011 摘要 ( 215 )   Flexible energy storage devices are essential for emerging flexible electronics. The existing state-of-the-art Li-ion batteries are slowly reaching their limitation in terms of cost and energy density. Hence, flexible Na-ion batteries (SIBs) with abundance Na resources and Li-S batteries with high energy density become the alternative for the Li-ion batteries in future. This review summarizes the recent advances in the development of flexible electrode materials for SIBs with metallic matrix and carbonaceous matrix such as carbon nano-tubes, carbon nano-fiber, graphene, carbon cloth, carbon fiber cloth, and cotton textiles. Then, the potential prototype flexible full SIBs are discussed. Further, the recent progress in the development of flexible electrode materials for Li-S batteries based on carbon nano-fiber, carbon nano-tubes, graphene, and cotton textiles is reviewed. Moreover, the design strategies of suitable interlayer, separator, electrolyte, and electrodes to prevent the dissolution and shuttle effect of polysulfides in flexible Li-S batteries are provided. Finally some prospective investigation trends towards future research of flexible SIBs and Li-S batteries are also proposed and discussed. The scientific and engineering knowledge gained on flexible SIBs and Li-S batteries provides conceivable development for practical application in near future.

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Synergistic impact of cocatalysts and hole scavenger for promoted photocatalytic H2 evolution in mesoporous TiO2-NiSx hybrid Yi Wei, Gang Cheng, Jinyan Xiong, Jiaxin Zhu, Yixin Gan, Mengmeng Zhang, Zhen Li, Shixue Dou 2019, 28(5): 45-56.  DOI: 10.1016/j.jechem.2018.05.013 摘要 ( 246 )   Photocatalytic solar energy conversion to hydrogen is sustainable and attractive for addressing the global energy and environmental issue. Herein, a novel photocatalytic system (NiS/Ni3S4 cocatalysts modified mesoporous TiO2) with superior photocatalytic hydrogen evolution capability through the synergistic impact of NiS/Ni3S4 (NiSx) cocatalyst and efficient hole scavenger has been demonstrated. The photocatalytic hydrogen evolution of TiO2-NiSx hybrids with the different content of NiSx and upon different organic hole scavengers was both investigated. The hybrid of TiO2 decorated with 3% (mole ratio of Ni2+) NiSx cocatalyst in methanol solution showed the optimal photocatalytic hydrogen evolution rate of 981.59 μmol h-1 g-1 which was about 20 times higher than that of bare mesoporous TiO2. Our results suggested that the boosted hydrogen production performance is attributed to both the improved photoinduced electrons migration between NiS and Ni3S4 in cocatalyst and the high hole captured efficiency by hole scavengers of methanol.

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Detrimental role of hydrogen evolution and its temperature-dependent impact on the performance of vanadium redox flow batteries Abdulmonem Fetyan, Gumaa A. El-Nagar, Iver Lauermann, Maike Schnucklake, Jonathan Schneider, Christina Roth 2019, 28(5): 57-62.  DOI: 10.1016/j.jechem.2018.06.010 摘要 ( 242 )   This paper addresses the damaging role of the parasitic hydrogen evolution reaction (HER) in the negative half-cell of a vanadium redox flow battery (VRFB) on state-of-the-art carbon felt electrodes at different temperatures. It was found that increasing the temperature resulted in a better catalytic performance for both the positive and negative half-cell reactions. In addition, increasing the temperature significantly enhanced the undesired HER at the negative side. Operating the VRFB cell at higher temperature led to a decrease in the coulombic efficiency attributed to the higher hydrogen production. More pronounced hydrogen production caused an oxidation on the surface of the carbon fibers and a degradation of the electrode as indicated from scanning electron microscopy and X-ray photoelectron spectroscopy measurements. This observed degradation results in fading of the overall performance of the vanadium redox flow battery over time.

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Fe-doped Co3O4@C nanoparticles derived from layered double hydroxide used as efficient electrocatalyst for oxygen evolution reaction Caiyun He, Xuzhao Han, Xianggui Kong, Meihong Jiang, Deqiang Lei, Xiaodong Lei 2019, 28(5): 63-70.  DOI: 10.1016/j.jechem.2018.06.014 摘要 ( 222 )   Compared with noble metal catalyst, Co3O4-based electrocatalysts have attracted considerable interesting as low-cost alternatives for oxygen evolution reaction (OER). However, the poor electrocatalytic activity still remains a huge challenge. Herein, we demonstrate a feasible approach through oxidation of CoFe layered double hydroxide (CoFe-LDH) to synthesize Fe-doped Co3O4@C nanoparticles with size of about 30-50 nm. As OER catalyst, the as-synthesized Fe-doped Co3O4@C nanoparticles exhibited superior OER performance with a small overpotential of 260 mV at the current density of 20 mA cm-2, a small Tafel slope of 70 mV dec-1 and long-term durability (there was no obviously OER current density degradation for 100 h) in alkaline solution. The present work opens a new avenue to the exploration of cost-effective and excellent electrocatalysts based on transition metal oxide materials to substitute precious metal materials for water splitting.

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Homogenizing the sulfonic acid distribution of DMF-modified PEDOT: PSS films and perovskite solar cells Hongliang Li, Cuiling Zhang, Yunping Ma, Zhiqiang Li, Ying Xu, Yaohua Mai 2019, 28(5): 71-77.  DOI: 10.1016/j.jechem.2018.06.013 摘要 ( 200 )   Inverted perovskite solar cells using pristine PEDOT:PSS as the hole-transporting layer (HTL) have been widely studied for its less hysteresis and low-temperature preparation technologies. However, this device suffers from an inferior open-circuit voltage (VOC) and stability problems. Several attempts have made on film formation and interface engineering to improve the efficiency. Modification proved beneficial to decrease energy offset at the interface between the HTL layer and the adjacent perovskite layer. In this paper, modification PEDOT:PSS layers were realized with a dimethyl formamide (DMF) solvent. The sulfonic acid distribution was homogenized in the normal direction after modification. The work function of the modified PEDOT:PSS layers increased from 4.71 to 5.07 eV, and the conductivity of modified PEDOT:PSS increased from 3×10-4 to 0.45 S/cm. The as-deposited perovskite films were more uniform with larger grain sizes and less pinholes, resulting in an improved VOC from 0.93 to 1.048 V, while the efficiency was increased from 11.5% to 16.8%. Solar cells without encapsulation under the 50 h and 50% humidity aging test showed 7% degradation of fill factor (FF) with 50 v/v% PEDOT:PSS layer, while the fill factor decreased 11.2% in the 0 v/v% PEDOT:PSS layer, respectively.

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Facile synthesis of molybdenum carbide nanoparticles in situ decorated on nitrogen-doped porous carbons for hydrogen evolution reaction Jin-Tao Ren, Yue-Jun Song, Zhong-Yong Yuan 2019, 28(5): 78-84.  DOI: 10.1016/j.jechem.2018.07.006 摘要 ( 217 )   Molybdenum-based electrocatalysts are promising candidates of platinum (Pt)-based materials in electrocatalyzing hydrogen evolution reaction (HER), due to their cost-efficient and resembled electronic properties. Reported herein is the preparation of molybdenum carbide nanoparticles uniformly decorated on nitrogen-modified carbons (Mo2C/NC) through the carbonization of Mo-based polymers under hydrogen atmosphere by using poly(p-phenylenediamine) and ammonium heptamolybdate polymer analogue as precursors. And the molybdenum nitride nanoparticles loaded on porous N-doped carbons (Mo2N/NC) are also fabricated by calcination the polymer precursors in nitrogen gas. The Mo2C/NC shows more excellent electrocatalytic activity than Mo2N/NC in 0.5 M H2SO4, together with robust long-term durability. The well-crystalline nanoparticles and the increased electron conductivity are the main characters responded for the high catalytic efficiency of the fabricated electrocatalysts. This easily fabrication procedure may provide a facile route to prepare non-noble metal carbide/nitride catalysts featuring wellengineered structural and textural peculiarities for realistic energy conversion system.

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Novel donor-acceptor-donor structured small molecular hole transporting materials for planar perovskite solar cells Xiaojuan Zhao, Yunyun Quan, Han Pan, Qingyun Li, Yan Shen, Zu-Sheng Huang, Mingkui Wang 2019, 28(5): 85-92.  DOI: 10.1016/j.jechem.2018.07.009 摘要 ( 227 )   Novel donor-acceptor-donor structured small molecular hole transporting materials are developed through a facile route by crosslinking dithienopyrrolobenzothiadiazole and phenothiazine or triarylamine-based donor units. The strong push/pull electron capability of dithienopyrrolobenzothiadiazole/phenothiazine and large π-conjugated dithienopyrrolobenzothiadiazole facilitate hole mobility and high conductivity. The devices using the dithienopyrrolobenzothiadiazole/phenothiazine-based hole transporting material achieved a power conversion efficiency of 14.2% under 1 sun illumination and improved stability under 20% relative humidity at room temperature without encapsulation. The present finding highlights the potential of dithienopyrrolobenzothiadiazole-based donor-acceptor-donor small molecular hole transporting materials for perovskite solar cells.

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Recent progress in functionalized layered double hydroxides and their application in efficient electrocatalytic water oxidation Xiaolong Deng, Jinzhao Huang, Hao Wan, Fashen Chen, Yifan Lin, Xijin Xu, Renzhi Ma, Takayoshi Sasaki 2019, 28(5): 93-104.  DOI: 10.1016/j.jechem.2018.07.007 摘要 ( 211 )   Layered double hydroxides (LDHs), a class of anionic clays consisting of brucite-like host layers and interlayer anions, have been widely investigated in the last decade due to their promising applications in many areas such as catalysis, ion separation and adsorption. Owing to the highly tunable composition and uniform distribution of metal cations in the brucite-like layers, as well as the facile exchangeability of intercalated anions, LDHs can be modified and functionalized to form various nanostructures/composites through versatile processes such as anion intercalation and exfoliation, decoration of nanoparticles, selfassembly with other two-dimensional (2D) materials, and controlled growth on conductive supports (e.g., nanowire arrays, nanotubes, 3D foams). In this article, we briefly review the recent advances on both the LDH nanostructures and functionalized composites toward the applications in energy conversion, especially for water oxidation.

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Thermal analysis of olive tree pruning and the by-products obtained by its gasification and pyrolysis: The effect of some heavy metals on their devolatilization behavior Irene Iáñez-Rodríguez, María Ángeles Martín-Lara, Gabriel Blázquez, Óscar Osegueda, Mónica Calero 2019, 28(5): 105-117.  DOI: 10.1016/j.jechem.2018.07.002 摘要 ( 216 )   In this work, the effect of the presence of nickel and lead in thermal decomposition of olive tree pruning (OTP), OTP-char and OTP-ashes was studied by thermogravimetry. Experiments were conducted in two kinds of atmosphere (nitrogen atmosphere and oxidizing atmosphere with 20% of O2) at a heating rate of 10℃/min. This investigation describes the chemical, physical and fuel properties of the OTP, which shows a similar composition to other lignocellulosic materials such as hazelnut husk and wood sawdust. In addition, SEM analysis indicated that OTP-char surface is higher than OTP surface with plenty of holes and channels. It makes the char an ideal support for metal retention specially for Pb metal (OTP retained 8.55 mg/g whereas OTP char retained 11.57 mg/g). On the other hand, metal retention occurred by adsorption or ion exchange, according to the IR spectrum of the samples. The results of thermogravimetric tests proved that the presence of lead did not have a strong effect on the decomposition of the samples, since TG and DTG curves were very similar. However, nickel increased the mass loss rate, accelerating the decomposition process, showing higher peaks in DTG curves. Additionally, for temperatures higher than 360℃, the volatilization of the samples was improved in the nickel-polluted sample, achieving a higher mass loss, getting more energy from the biomass and reducing the quantity of residues left after the process.

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Characterization of CoMn catalyst by in situ X-ray absorption spectroscopy and wavelet analysis for Fischer-Tropsch to olefins reaction Ruoou Yang, Zhaoming Xia, Ziang Zhao, Fanfei Sun, Xianlong Du, Haisheng Yu, Songqi Gu, Liangshu Zhong, Jingtai Zhao, Yunjie Ding, Zheng Jiang 2019, 28(5): 118-123.  DOI: 10.1016/j.jechem.2018.07.005 摘要 ( 209 )   Cobalt carbide has recently been reported to catalyse the FTO conversion of syngas with high selectivity for the production of lower olefins (C2-C4). Clarifying the formation process and atomic structure of cobalt carbide will help understand the catalytic mechanism of FTO. Herein, hydrogenation of carbon monoxide was investigated for cobalt carbide synthesized from CoMn catalyst, followed by X-ray diffraction, transmission electron microscopy, temperature programmed reaction and in situ X-ray absorption spectroscopy. By monitoring the evolution of cobalt carbide during syngas conversion, the wavelet transform results give evidence for the formation of the cobalt carbide and clearly demonstrate that the active site of catalysis was cobalt carbide.

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Yolk-shell Si/C composites with multiple Si nanoparticles encapsulated into double carbon shells as lithium-ion battery anodes Le Hu, Bin Luo, Chenghao Wu, Pengfei Hu, Lianzhou Wang, Haijiao Zhang 2019, 28(5): 124-130.  DOI: 10.1016/j.jechem.2018.07.008 摘要 ( 194 )   The conceptual design of yolk-shell structured Si/C composites is considered to be an effective way to improve the recyclability and conductivity of Si-based anode materials. Herein, a new type of yolk-shell structured Si/C composite (denoted as TSC-PDA-B) has been intelligently designed by rational engineering and precise control. In the novel structure, the multiple Si nanoparticles with small size are successfully encapsulated into the porous carbon shells with double layers benefiting from the strong etching effect of HF. The TSC-PDA-B product prepared is evaluated as anode materials for lithium-ion batteries (LIBs). The TSC-PDA-B product exhibits an excellent lithium storage performance with a high initial capacity of 2108 mAh g-1 at a current density of 100 mA g-1 and superior cycling performance of 1113 mAh g-1 over 200 cycles. The enhancement of lithium storage performance may be attributed to the construction of hybrid structure including small Si nanoparticles, high surface area, and double carbon shells, which can not only increase electrical conductivity and intimate electrical contact with Si nanoparticles, but also provide built-in buffer voids for Si nanoparticles to expand freely without damaging the carbon layer. The present findings can provide some scientific insights into the design and the application of advanced Si-based anode materials in energy storage fields.

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Probing the intrinsic catalytic activity of carbon nanotubes for the metal-free oxidation of aromatic thiophene compounds in ionic liquids Qingqing Gu, Yuxiao Ding, Zigeng Liu, Yangming Lin, Robert Schlögl, Saskia Heumann, Dangsheng Su 2019, 28(5): 131-137.  DOI: 10.1016/j.jechem.2018.07.004 摘要 ( 255 )   A metal-free catalytic system combining oxidized carbon nanotubes (oCNTs) and ionic liquids (ILs) is presented for the oxidation of aromatic thiophene compounds with H2O2 as an oxidant. The oCNTs exhibit impressively high activity and stability in the system, which show an even better performance than those of some reported metal catalysts. The ILs are proved to have indispensable influence on the enhanced catalytic performance of the oCNTs. Detailed characterization by TG-MS and XPS demonstrates that the carbonyl groups are the active sites for the oxidation process, which is further supported by the deactivation and the model catalysts experiments. The quantitative analysis of different oxygen groups in oCNTs could be achieved by an isothermal temperature programmed TG-MS method. The concentration of carbonyl groups is 1.46 mmol per 1 g oCNTs and the turnover frequency of oCNTs could also be obtained (10.7 h-1 in the presence of OmimPF6). H2O2 decomposition experiments combined with the EPR results reveal that the presence of OmimPF6 can avoid the intermediate HO·to form O2 and then improve the catalytic performance of oCNTs for the oxidation of dibenzothiophene.

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Catalytic conversion of cellulose-based biomass and glycerol to lactic acid Shi Li, Weiping Deng, Yanyun Li, Qinghong Zhang, Ye Wang 2019, 28(5): 138-151.  DOI: 10.1016/j.jechem.2018.07.012 摘要 ( 236 )   Catalytic transformation of cellulose into value-added chemicals is of great importance for utilization of renewable and abundant biomass. Due to the high oxygen content, cellulose serves as an ideal candidate for the production of oxygenates, in particular lactic acid which is a versatile building block in chemical industry. The efficient conversion of cellulose to lactic acid generally requires selective activation of specific C-O and C-C bonds, and therefore multifunctional catalysts that combine several key reactions including hydrolysis, isomerization and retro-aldol fragmentation are highly desirable. This review article highlights the recently developed catalytic systems and catalysts for the selective transformation of cellulose and cellulose-derived carbohydrates into lactic acid, lactates and/or its esters. Emphases will be put on the reaction mechanism and key factors that exert effects on the catalytic performances. In addition, the catalytic transformation of glycerol, a C3 compound over-supplied from biodiesel industry, will also be surveyed. Recent advances in the development of new catalysts or strategies are analyzed and discussed to gain insight into the transformation of C3 compound to lactic acid.

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High isotropic dispiro structure hole transporting materials for planar perovskite solar cells Bin Cai, Xichuan Yang, Haoxin Wang, Weihan Wang, Jincheng An, Licheng Sun 2019, 28(5): 152-158.  DOI: 10.1016/j.jechem.2018.07.013 摘要 ( 211 )   Two novel fluorene-based hole transporting materials (HTMs) were synthesized to be used in perovskite solar cells (PSCs). C102 was designed based on C101 by simply linking the two carbon-carbon single bonds to compose a "dispiro" structure. Their typically similar structures cause them sharing almost the same energy levels. However, their photovoltaic performances are quite different due to the small variations. The PSC that contained the "dispiro" structure, C102, reached a power conversion efficiency (PCE) of 17.4%, while the device contained C101, obtained a lower PCE of 15.5%. Electrochemical properties and Photovoltaic characterization of the two materials have been investigated to explain the result. It is shown that C102 has a stronger ability to transport holes and resist the charge recombination. Thus, the dispiro structure should be more appropriate being used as HTM in PSCs.

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Facile synthesis of Li3V2(PO4)3/C cathode material for lithium-ion battery via freeze-drying Shuainan Guo, Ying Bai, Zhenfeng Geng, Feng Wu, Chuan Wu 2019, 28(5): 159-165.  DOI: 10.1016/j.jechem.2018.07.011 摘要 ( 215 )   In this work, we report a facile route for the synthesis of Li3V2(PO4)3/C cathode material via freezedrying and then calcination. The effect of calcination temperature on the electrochemical properties of the Li3V2(PO4)3/C is also investigated. When used as a lithium-ion battery cathode, the optimized Li3V2(PO4)3/C (LVP-800) through calcination at 800℃ exhibits a high initial charge and discharge capacity. The excellent electrochemical performance of LVP-800 is attributed to the good crystallinity and uniform morphology of the electrode material. In addition, the residual carbon can also improve the conductivity and buffer the volume expansion during the Li-ion extraction/reinsertion. Meanwhile, charge compensation also plays an important role in excellent electrochemical performance.

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A flexible solid-state supercapacitor based on graphene/polyaniline paper electrodes Kang Li, Xuanli Liu, Song Chen, Wei Pan, Jintao Zhang 2019, 28(5): 166-173.  DOI: 10.1016/j.jechem.2018.07.014 摘要 ( 209 )   The direct coating of graphene sheets obtained by electrochemical exfoliation on commercial paper renders the preparation of highly conductive flexible paper substrate for subsequent deposition of polyaniline (PANi) nanorods via electrochemical polymerization. The deposition of PANi can be well-controlled by adjusting the electrochemical polymerization time, leading to the formation of PANi coated graphene paper (PANi-GP). The as-prepared electrode exhibited high areal capacitance of 176 mF cm-2 in threeelectrode system at a current density of 0.2 mA cm-2, which is around 10 times larger than that of pristine graphene paper due to the pseudocapacitive behavior of PANi. In-situ Raman test was used to determine the molecular changes during redox process of PANi. More importantly, all-solid-state symmetric capacitor assembled with two PANi-GP electrodes in a polymer electrolyte delivered an areal capacitance of 123 mF cm-2, corresponding to an areal energy density of 17.1 μWh cm-2 and an areal power density of 0.25 mW cm-2. The symmetric capacitor held a capacitive retention of 74.8% after 500 bending tests from 0 to 120°, suggesting the good flexibility and mechanical stability. These results showed the great promising application in flexible energy-storage devices.

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The template-assisted zinc ion incorporation in SAPO-34 and the enhanced ethylene selectivity in MTO reaction Jiawei Zhong, Jingfeng Han, Yingxu Wei, Shutao Xu, Tantan Sun, Xinwen Guo, Chunshan Song, Zhongmin Liu 2019, 28(5): 174-181.  DOI: 10.1016/j.jechem.2018.07.017 摘要 ( 237 )   The SAPO-34 catalyst was fine-tuned with zinc cations through a straightforward template-assisted ion incorporation (TⅡ) process, without the necessary template pre-removal and the preparation of NH4-SAPO-34 intermediate, which is more facile, efficient and cost-effective than the conventional ion exchange process. The template-assisted zinc cations incorporated SAPO-34 catalysts were characterized by XRD, XRF, N2 adsorption-desorption, XPS, SEM, EDX, 1H NMR, respectively. Enhanced selectivity to ethylene and ratio of ethylene to propylene in MTO reaction are observed over the zinc cations modified SAPO-34 catalysts, due to the facilitated formation of lower methylbenzenes that favour the ethylene generation, as well as the increased diffusion hindrance originated from the zinc cations incorporation and the facilitated generation of aromatics compound.

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Effect of rich R-TiO2 on the rate and cycle properties of Li4Ti5O12 as anode for lithium ion batteries Delai Qian, Yijie Gu, Shuainan Guo, Hongquan Liu, Yunbo Chen, Juan Wang, Guoxuan Ma, Chuan Wu 2019, 28(5): 182-188.  DOI: 10.1016/j.jechem.2018.07.016 摘要 ( 186 )   Li4Ti5O12 (LTO) with rich R-TiO2 (17.06, 23.69, and 34.42 wt%), namely, R-TiO2@Li4Ti5O12 composites, were synthesized using the hydrothermal method and tetrabutyl titanate (TBT) as the precursor. Rietveld refinement of X-ray diffraction (XRD) results show that the proportion of Li occupying 16d sites is extraordinary low and the lattice constants of LTO and R-TiO2 change with the titanium dioxide content. EIS measurements showed that with increasing R-TiO2 content, both its charge transfer impedance (Rct) and lithium ion diffusion coefficient (DLi) decreased. The changes of Rct and DLi caused by the increase of titanium dioxide content have synergic-antagonistic effects on the rate and cycle properties of Li4Ti5O12. The rate performance is positively related to DLi, while the cycle property is negatively correlated with Rct, indicating that the rate performance is mainly related to DLi, while Rct more significantly affects the cycle performance. LTO-RT-17.06% exhibited excellent rate properties, especially under a high current density (5.0 C, 132.5 mAh/g) and LTO-RT-34.42% showed superior long-term cycle performance (0.012% capacity loss per cycle) compared to that of LTO-RT-17.06% and LTO-RT-23.69%.

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Catalytic transfer hydrogenation of levulinate ester into γ -valerolactone over ternary Cu/ZnO/Al2O3 catalyst Chuntao Zhang, Zhibao Huo, Dezhang Ren, Zhiyuan Song, Yunjie Liu, Fangming Jin, Wanning Zhou 2019, 28(5): 189-197.  DOI: 10.1016/j.jechem.2018.08.001 摘要 ( 213 )   An effective catalytic transfer hydrogenation (CTH) process of bio-based levulinate esters into γ-valerolactone (GVL) was explored over ternary Cu/ZnO/Al2O3 catalyst which was prepared by coprecipitation method and could be sustainably used. As a result, quantitative conversion of ethyl levulinate (EL) and 99.0% yield of GVL were obtained in the CTH process using #em/em#-PrOH as hydrogen donor. The Cu/ZnO/Al2O3 catalyst with high-surface-area could be reused at least four times without the loss of catalytic activity. Furthermore, the structure and properties of Cu/ZnO/Al2O3 catalyst was characterized through XRD, BET, SEM, TEM and H2-TPR. Also, the influence of different support oxides and calcination temperatures was investigated.