Journal of Energy Chemistry
ISSN 1003-9953
     
能源化学(英文)

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Wang and coworkers in their article on pages 127-137 reported a novel high-temperature CO2 adsorbent composited with Mg- Al layered double hydroxide (LDH) and graphene oxide (GO) nanosheets. It exhibited good CO2 adsorption capacity and was particularly available for the sorption enhanced water gas shift (SEWGS) process. This work demonstrated a new approach for preparation of the LDH-based hybrid-type adsorbents for CO2 capture.


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2015 Vol.24 No.2, Published: 2015-03-23
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Synthesis of layered double hydroxides/graphene oxide nanocomposite as a novel high-temperature CO2 adsorbent
Junya Wang, Xueyi Mei, Liang Huang, Qianwen Zheng, Yaqian Qiao, Ketao Zang, Shengcheng Mao, Ruoyan Yang, Zhang Zhang, Yanshan Gao, Zhanhu Guo, Zhanggen Huang, Qiang Wang
2015 Vol. 24 (2): 127-137 [Abstract] ( 190 ) [HTML 1KB] [PDF] ( 0 )

In this contribution, a novel high-temperature CO2 adsorbent consisting of Mg-Al layered double hydroxide (LDH) and graphene oxide (GO) nanosheets was prepared and evaluated. The nanocomposite-type adsorbent was synthesized based on the electrostatically driven self-assembly between positively charged Mg-Al LDH single sheet and negatively charged GO monolayer. The characteristics of this novel adsorbent were investigated using XRD, FE-SEM, HRTEM, FT-IR, BET and TGA. The results showed that both the CO2 adsorption capacity and the multi-cycle stability of LDH were increased with the addition of GO owing to the enhanced particle dispersion and stabilization. In particular, the absolute CO2 capture capacity of LDH was increased by more than twice by adding 6.54 wt% GO as support. GO appeared to be especially effective for supporting LDH sheets. Moreover, the CO2 capture capacity of the adsorbent could be further increased by doping with 15 wt% K2CO3. This work demonstrated a new approach for the preparation of LDH-based hybrid-type adsorbents for CO2 capture.

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Surface modification of polyolefin separators for lithium ion batteries to reduce thermal shrinkage without thickness increase
Peng Zhao, Juping Yang, Yuming Shang, Li Wang, Mou Fang, Jianlong Wang, Xiangming He
2015 Vol. 24 (2): 138-144 [Abstract] ( 172 ) [HTML 1KB] [PDF] ( 0 )

Surface chemical modification of polyolefin separators for lithium ion batteries is attempted to reduce the thermal shrinkage, which is important for the battery energy density. In this study, we grafted organic/inorganic hybrid crosslinked networks on the separators, simply by grafting polymerization and condensation reaction. The considerable silicon-oxygen crosslinked heat-resistance networks are responsible for the reduced thermal shrinkage. The strong chemical bonds between networks and separators promise enough mechanical support even at high temperature. The shrinkage at 150℃ for 30 min in the mechanical direction was 38.6% and 4.6% for the pristine and present graft-modified separators, respectively. Meanwhile, the grafting organic-inorganic hybrid crosslink networks mainly occupied part of void in the internal pores of the separators, so the thicknesses of the graft-modified separators were similar with the pristine one. The half cells prepared with the modified separators exhibited almost identical electrochemical properties to those with the commercial separators, thus proving that, in order to enhance the thermal stability of lithium ion battery, this kind of grafting-modified separators may be a better alternative to conventional silica nanoparticle layers-coated polyolefin separators.

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Electrostatic self-assembly of CdS nanowires-nitrogen doped graphene nanocomposites for enhanced visible light photocatalysis
Bin Han, Siqi Liu, Zi-Rong Tang, Yi-Jun Xu
2015 Vol. 24 (2): 145-156 [Abstract] ( 170 ) [HTML 1KB] [PDF] ( 0 )

CdS nanowires-nitrogen doped graphene (CdS NWs-NGR) nanocomposites have been fabricated by an electrostatic self-assembly strategy followed by a hydrothermal reduction. The CdS NWs-NGR exhibits higher photoactivity for selective reduction of aromatic nitro organics in water under visible light irradiation than blank CdS nanowires (CdS NWs) and CdS nanowires-reduced graphene oxide (CdS NWs-RGO) nanocomposites. The enhanced photoactivity of CdS NWs-NGR can be attributed to the improved electronic conductivity due to the introduction of nitrogen atoms, which thus enhances the separation and transfer of charge carriers photogenerated from CdS NWs. Our work could provide a facile method to synthesize NGR based one-dimensional (1D) semiconductor composites for selective organic transformations, and broaden the potential applications for NGR as a cocatalyst.

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Enhanced electrochemical performance of Li-ion batteries with nanoporous titania as negative electrodes
Md. Arafat Rahman, Xiaojian Wang, Cuie Wen
2015 Vol. 24 (2): 157-170 [Abstract] ( 173 ) [HTML 1KB] [PDF] ( 0 )

Nanoporous anatase TiO2 (np-TiO2) electrodes have been developed via the anodization of titanium foils in fluoride containing electrolytes, and its application in rechargeable lithium-ion batteries (LIBs) was investigated. Four different types of np-TiO2 electrodes with different pore diameters of 14.7±8.2nm, 12.8±6.8nm, 11.0±5.5, and 26.7±13.6nm were fabricated for evaluating the effect of nanoporous characteristics on the LIB performance. The discharge capacity of the four battery types 1, 2, 3, and 4 were 132.7 mAh·g-1, 316.7 mAh·g-1, 154.3 mAh·g-1, and 228.4 mAh·g-1, respectively. In addition, these electrodes 1, 2, 3, and 4 exhibited reversible capacity of 106.9 mAh·g-1 after 295th, 180.9 mAh·g-1 after 220th, 126.1 mAh·g-1 after 150th, and 206.7 mAh·g-1 after 85th cycle at a rate of 1 C, respectively. It was noted that the cyclic life of the batteries had an inverse relationship, and the capacity had a proportional relationship to the pore diameter. The enhanced electrochemical performance of the nanoporous electrodes can be attributed to the improved conductivity and the enhanced kinetics of lithium insertion/extraction at electrode/electrolyte interfaces because of the large specific surface area of np-TiO2 electrodes.

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Morphology dependent photocatalytic activity of WO3 nanostructures
Mousa Farhadian, Parvaneh Sangpour, Ghader Hosseinzadeh
2015 Vol. 24 (2): 171-177 [Abstract] ( 142 ) [HTML 1KB] [PDF] ( 0 )

The shape of nanostructure has important effects on their properties, therefore in this study, we have prepared and characterized three different morphologies of WO3 nanostructures i.e. nanorod, nanosphere and nanoplate for surveying shape effect on their photocatalytic properties toward degradation of Rhodamine B (RhB) dye. Obtained results show that nanoplate WO3 in comparison with others has the best photocatalytic activity. According to SEM, and photocatalytic degradation results, the reason for this behavior is the sharp edges and corners of WO3 nanoplates. Because of their low coordination number, atoms located in the edges and corners of the WO3 nanoplates have more activity, adsorb more RhB and therefore give more photocatalytic activity to the WO3 nanoplates. Using of different scavengers showed that hydroxyl radicals are mainly responsible for photocatalytic activity of WO3 nanoplates and nanospheres but for WO3 nanorods, superoxide radicals are the main photocatalytic degradation agents.

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Ozone electrogeneration on Pt-TaOy sol-gel film modified titanium electrode: Effect of electrode composition on the electrocatalytic activity
Mohamed I. Awad, Shunsuke Sata, Kazuhiro Kaneda, Mineo Ikematsu, Takeo Ohsaka
2015 Vol. 24 (2): 178-184 [Abstract] ( 156 ) [HTML 1KB] [PDF] ( 0 )

This work examines the ozone electrogeneration (OE) at a binary coating of different nominal compositions (Pt)x-(TaOy)(100-x), where x (percentage in the precursor solution) varied between 1% and 100%, coated on titanium substrate prepared by a sol-gel technique. The OE is performed in an artificial tap water at room temperature (25℃). The percentages of Pt and TaOy in the coating significantly affect the electrocatalytic activity towards oxygen evolution. The oxygen evolution was retarded to a different extent based on the electrode composition. The largest retardation was obtained at the (Pt)10-(TaOy)90 electrode (ca. 480mV positive shift) as compared with the (Pt)100-(TaOy)0 electrode. This was reflected in a high current efficiency (CE) of OE (ca. 19.3%) at the former electrode. This value is considered to be among the highest values reported for OE at 25℃ in neutral media. The composite electrodes were characterized by voltammetric and surface techniques. A plausible explanation for the change of the efficiency of OE with the electrode composition is given based on the electrochemical results.

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Preparation, characterization and hydrodesulfurization performances of Co-Ni2P/SBA-15 catalysts
Zhou-jun Wang, Pingyi Wu, Ling Lan, Kunhong Liu, Yaqiong Hu, Shengfu Ji
2015 Vol. 24 (2): 185-192 [Abstract] ( 148 ) [HTML 1KB] [PDF] ( 0 )

A series of Co-Ni2P/SBA-15 catalysts with various Co contents, Ni2P contents and P/Ni molar ratios were prepared by impregnating nickel nitrate, diammonium hydrogen phosphate, and then cobalt nitrate into SBA-15 support followed by temperature-programmed reduction in a H2 flow. The catalyst structure was characterized by X-ray diffraction (XRD), high resolution-transmission electron microscopy (HR-TEM) and N2 adsorption-desorption techniques and their catalytic performance of the hydrodesulfurization (HDS) of dibenzothiophene (DBT) was evaluated. The effects of Co contents, Ni2P contents and P/Ni molar ratios on the catalyst structure and HDS of DBT over the Co-Ni2P/SBA-15 catalyst were investigated. The results indicated that the mesoporous structure was mainly maintained and the nickel phosphides were well dispersed in all of the characterized catalysts. The 4Co-25Ni2P/SBA-15 (P/Ni=0.8) catalyst with the Co and Ni2P contents of 4 wt% and 25 wt%, respectively, and the P/Ni molar ratio of 0.8 showed the highest catalytic performance for HDS of DBT. Under the reaction conditions of 380℃ and 3.0MPa, the DBT conversion can reach 99.62%. The HDS of DBT proceeded mainly via the direct desulfurization (DDS) pathway with biphenyl (BP) as the dominant product on all of the catalysts and the BP selectivity was slightly enhanced after the introduction of Co promoters.

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Novel application of LiCoO2 as a high-performance candidate material for supercapacitor
Yanan Xu, Liangzhong Ding, Tongsheng Zhong, Xiao Han, Lifang Jiao, Huatang Yuan, Yijing Wang
2015 Vol. 24 (2): 193-198 [Abstract] ( 151 ) [HTML 1KB] [PDF] ( 0 )

Electrochemical performances of LiCoO2 as a candidate material for supercapacitor are systematically investigated. LiCoO2 nanomaterials are synthesized via hydrothermal reaction with consequent calcination process. And the particle size increases as the calcination temperature rises. LCO-650 sample with the largest particle size displays the maximum capacitances of 817.5 F·g-1 with the most outstanding capacity retention rate of 96.8% after 2000 cycles. It is shown that large particle size is beneficial to the electrochemical and structural stability of LiCoO2 materials. We speculate that the micron-sized waste LiCoO2 materials have great potential for supercapacitor application. It may provide a novel recovered approach for spent LIBs and effectively relieve the burdens on the resource waste and environment pollution.

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Development of proton-conducting membrane based on incorporating a proton conductor 1,2,4-triazolium methanesulfonate into the Nafion membrane
Jinkai Hao, Xiaojin Li, Shuchun Yu, Yongyi Jiang, Jiangshui Luo, Zhigang Shao, Baolian Yi
2015 Vol. 24 (2): 199-206 [Abstract] ( 166 ) [HTML 1KB] [PDF] ( 0 )

In this paper, 1,2,4-triazolium methanesulfonate (C2H4N3+CH3SO3-, [Tri][MS]), an ionic conductor, was successfully synthesized. It exhibited high ionic conductivity of 18.60 mS·cm-1 at 140℃ and reached up to 36.51 mS·cm-1 at 190℃. [Tri][MS] was first applied to modify Nafion membrane to fabricate [Tri][MS]/Nafion membrane by impregnation method at 150℃. The prepared composite membrane showed high thermal stability with decomposed temperature above 200℃ in air atmosphere. In addition, the membrane indicated good ionic conductivity with 3.67 mS·cm-1 at 140℃ and reached up to 13.23 mS·cm-1 at 180℃. The structure of the [Tri][MS] and the composite membrane were characterized by FTIR and the compatibility of [Tri][MS] and Pt/C catalyst was studied by a cyclic voltammetry (CV) method. Besides, the [Tri][MS]/Nafion membrane (thickness of 65 μm) was evaluated with single fuel cell at high temperature and without humidification. The highest power density of [Tri][MS]/Nafion membrane was 3.20 mW·cm-2 at 140℃ and 4.90 mW·cm-2 at 150℃, which was much higher than that of Nafion membrane.

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Improved two-step hydrothermal process for acetic acidproduction from carbohydrate biomass
Zhibao Huo, Yan Fang, Guodong Yao, Xu Zeng, Dezhang Ren, Fangming Jin
2015 Vol. 24 (2): 207-212 [Abstract] ( 134 ) [HTML 1KB] [PDF] ( 0 )

An improved two-step process for converting carbohydrate biomass to acetic acid under hydrothermal conditions is proposed. The first step consists of the production of lactic acid from carbohydrate biomass, and the second step consists of conversion of the lactic acid obtained in the first step to acetic acid using CuO as an oxidant. The results indicated that CuO as an oxidant in the second step can significantly improve the production of high-purity acetic acid from lactic acid, and the maximum yield of acetic acid was 61%, with a purity of 90%. The yield of acetic acid obtained using the improved two-step hydrothermal process from carbohydrate biomass, such as glucose, cellulose and starch, was greater than that obtained using traditional two-step process with H2O2 or O2. In addition, a proposed pathway for the production of acetic acid from lactic acid in the second step with CuO was also discussed. The present study provides a useful two-step process for the production of acetic acid from carbohydrate biomass.

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Carbon matrix effects on the micro-structure and performance of Pt nanowire cathode prepared by decal transfer method
Zhaoxu Wei, An He, Kaihua Su, Sheng Sui
2015 Vol. 24 (2): 213-218 [Abstract] ( 155 ) [HTML 1KB] [PDF] ( 0 )

High performance cathode for polymer electrolyte membrane fuel cell was prepared by depositing Pt nanowires in a carbon matrix coated on a substrate, and using decal transfer method to fabricate the membrane electrode assembly. The effects of carbon and ionomer contents on the electrode micro-structure and fuel cell performance are investigated by physical characterization and single cell testing. The Pt nanowires are gradient distributed across the cathode thickness, and more Pt exists near the membrane. Both the carbon and ionomer contents can affect the Pt nanowires distribution and aggregation. In addition, the carbon loading dominates the transport distance of gas and proton, and the ionomer content affects the triple phase boundaries and porosity in the cathode. The optimal structure of Pt nanowire cathode is obtained at 0.10 mg·cm-2 carbon loading and 10 wt% ionomer.

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Identification of the starting reaction position in the hydrogenation of (N-ethyl)carbazole over Raney-Ni
Feifei Sun, Yue An, Lecheng Lei, Fuying Wu, Jingke Zhu, Xingwang Zhang
2015 Vol. 24 (2): 219-224 [Abstract] ( 124 ) [HTML 1KB] [PDF] ( 0 )

Hydrogenation of carbazole and N-ethylcarbazole over Raney-Ni catalyst were realized in the temperature range of 393-503K. 4[H] adduct dominated the hydrogenation products and the formation of 2[H] adduct was the rate-limiting step during the period, in which the conversion of carbazole was less than 40%. The hydrogenation process followed pseudo-first-order kinetics and the hydrogenation activation energies of carbazole and N-ethylcarbazole were 90kJ/mol and 115kJ/mol, respectively. The reaction starting position as well as the pathway of the hydrogenation of (N-ethyl)carbazole were investigated by comparing the kinetic characteristics of hydrogen uptake of carbazole and N-ethylcarbazole. The results showed that the reaction was a stepwise hydrogenation process and the first H2 was added to the C1=C10 double bond in the hydrogenation.

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The role of nickel oxide additive in lowering the carbon dioxide sorption temperature of CaO
Zhi Hua Lee, Satoshi Ichikawa, Keat Teong Lee, Abdul Rahman Mohamed
2015 Vol. 24 (2): 225-231 [Abstract] ( 162 ) [HTML 1KB] [PDF] ( 0 )

A new type of calcium-based regenerable carbon dioxide (CO2) sorbent, CaO-NiO, was synthesized via the sol-gel method. The as synthesized CO2 sorbent was in the form of nanoparticles. The CO2 sorption temperature and capacity of the sorbent were examined using thermogravimetric analysis (TGA). The CaO-NiO sorbent is able to capture CO2 at a lower sorption temperature (465℃) than pure calcium oxide (CaO) (600℃). The role of NiO in the CaO-NiO sorbent in lowering the CO2 sorption temperature was also investigated. The sorbent was characterized by X-ray diffractometer (XRD), N2 adsorption-desorption analysis, high resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM). CaO and NiO were found to coexist in the sorbent. Neither solid solution nor mixed metal oxide was formed. NiO did not react with CO2 in the sorption process; but it worked like a catalyst to promote the CaO carbonation reaction. It is suggested that this new CaO-NiO sorbent may have a promising application as an effective CO2 sorbent with lower energy consumption.

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Ru effect on the catalytic performance of Pd@Ru/C catalystsfor methanol electro-oxidation
Yanbiao Ren, Shichao Zhang, Xin Wei
2015 Vol. 24 (2): 232-238 [Abstract] ( 150 ) [HTML 1KB] [PDF] ( 0 )

Pd@Ru bimetallic nanoparticles deposited on carbon black electro-catalysts have been fabricated by microwave-assisted polyol reduction method and investigated for methanol electro-oxidation (MEO). The structure and electro-catalytic properties of the as-prepared catalysts were characterized by XRD, SEM, TEM and cyclic voltammetry (CV) techniques. The results showed that the introduction of Ru element (2-10 wt%) into Pd 20 wt%/C (hereafter, denoted as Pd/C) produced a series of core-shell structured binary catalysts. Pd@Ru 5 wt%/C (hereafter, denoted as Pd@Ru5/C) catalyst displayed the highest catalytic activity towards MEO. And the mass activity of Pd@Ru5/C electrode catalyst at E=-0.038V (vs. Hg/HgO) was 1.42 times higher than that of Pd/C electrode catalyst. In addition, the relationship between the catalytic stability for MEO on Pd@Ru/C catalysts and the value of Jbp/Jfp (the ratio of MEO peak current density in the negative scan and positive scan) were also investigated. The result demonstrated that Pd@Ru5/C offering the smallest value of Jbp/Jfp displayed the best stable catalytic performance.

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Chemical equilibrium controlled synthesis of polyoxymethylene dimethyl ethers over sulfated titania
Huaju Li, Huanling Song, Feng Zhao, Liwei Chen, Chungu Xia
2015 Vol. 24 (2): 239-244 [Abstract] ( 134 ) [HTML 1KB] [PDF] ( 0 )

The chemical equilibrium and reaction kinetic behavior in the synthesis of polyoxymethylene dimethyl ethers (DMMn) were investigated over sulfated titania in order to reveal the decisive factor controlling the reaction. The results showed that the molar ratio of adjacent DMMn products in equilibrium solution had the same value, which depended absolutely on the reaction temperature. Meanwhile, the reactions had the same DMMn products distributions under varied reaction conditions. The equilibrium constants of the related step-wise reactions for DMMn formation were equal, which were calculated based on the bulk compositions of the reaction solution. And thus, the selectivity to DMMn was mainly controlled by the chemical equilibrium, i.e., thermodynamic control. In brief, the present results provide some guidance for future synthesis of DMMn.

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Adsorption isotherms and kinetic characteristics of methane on block anthracite over a wide pressure range
Wanli Xing, Yongchen Song, Yi Zhang, Weiguo Liu, Lanlan Jiang, Yanghui Li, Yuechao Zhao
2015 Vol. 24 (2): 245-256 [Abstract] ( 165 ) [HTML 1KB] [PDF] ( 0 )

It is important to quantitatively understand the methane adsorption and transport mechanism in coal for an evaluation of the reserves and for its production forecast. In this work, a block coal sample was chosen to perform the CH4 adsorption experiments using the gravimetric method at temperatures of 293.60K, 311.26K, 332.98K and 352.55K and pressures up to 19MPa. The excess adsorption capacity of CH4 in dry block anthracite increased, followed by a sequence decrease with the increasing pressure. High temperature restrained the growth of the excess adsorption due to that the adsorption is an intrinsically physical and exothermic process. The excess adsorption peak decreased slowly with the increase of temperature and intersected at a pressure of more than 18 MPa; meanwhile, the pressure at the excess adsorption peak increased. The existing correlations were examined in terms of density rather than pressure. The DR+k correlation, with an average relative deviation of ±0.51%, fitted our data better than the others, with an average relative deviation of up to 2.29%. The transportation characteristics of CH4 adsorption was also investigated in this study, including the adsorption rate and diffusion in block coal. The kinetic data could be described by a modified unipore model. The adsorption rates were found to exhibit dependence on pressure and temperature at low pressures, while the calculated diffusivities exhibited little temperature dependence. In addition, the kinetic characteristics were compared between CH4 and CO2 adsorption on the block coal. The excess adsorption ratios of CO2 to CH4 obtained from the DR+k model decreased with the increasing pressure.

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Bimonthly
(Started in 1992)
Renamed from JNGC in 2013

ISSN 2095-4956
CN 21-1585/O4

Editors-in-Chief
Xinhe Bao
Alexis T. Bell


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Journal of Energy Chemistry

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