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2017, Vol. 26, No. 1　Online: 2017-01-15


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Catalytical effect of bismuth: Vanadium flow battery

 

This paper systemically researches the catalytical effect of bismuth on both V³⁺/V²⁺ and VO²⁺/VO²⁺ redox couples by introducing bismuth onto the carbon felt as electrode for both sides.The results show that bismuth would be oxidized into Bi³⁺ on positive side and thus present no catalytic activity.On the contrary,bismuth is stable on negative side and can significantly improve the reaction of V³⁺/V²⁺redox couple.

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The catalytic effect of bismuth for VO2+/VO2+ and V3+/V2+ redox couples in vanadium flow batteries Xiaofei Yang, Tao Liu, Chi Xu, Hongzhang Zhang, Xianfeng Li, Huamin Zhang 2017, 26(1): 1-7.  DOI: 10.1016/j.jechem.2016.09.007 摘要 ( 6634 )   PDF(709KB) ( 3 )   The effect of bismuth (Bi) for both VO2+/VO2+ and V3+/V2+ redox couples in vanadium flow batteries (VFBs) has been investigated by directly introducing Bi on the surface of carbon felt (CF). The results show that Bi has no catalytic effect for VO2+/VO2+ redox couple. During the first charge process, Bi is oxidized to Bi3+ (never return back to Bi metal in the subsequent cycles) due to the low standard redox potential of 0.308 V (vs. SHE) for Bi3+/Bi redox couple compared with VO2+/VO2+ redox couple and Bi3+ exhibit no (or neglectable) electro-catalytic activity. Additionally, the relationship between Bi loading and electrochemical activity for V3+/V2+ redox couple was studied in detail. 2 wt% Bi-modified carbon felt (2%-BiCF) exhibits the highest electrochemical activity. Using it as negative electrode, a high energy efficiency (EE) of 79.0% can be achieved at a high current density of 160 mA/cm2, which is 5.5% higher than the pristine one. Moreover, the electrolyte utilization ratio is also increased by more than 30%. Even the cell operated at 140 mA/cm2 for over 300 cycles, the EE can reach 80.9% without obvious fluctuation and attenuation, suggesting excellent catalytic activity and electrochemical stability in VFBs.

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Palladium and carbon synergistically catalyzed room-temperature hydrodeoxygenation (HDO) of vanillyl alcohol-A typical lignin model molecule Qi Wang, Neeraj Gupta, Guodong Wen, Sharifah Bee Abd Hamid, Dang Sheng Su 2017, 26(1): 8-16.  DOI: 10.1016/j.jechem.2016.09.005 摘要 ( 4990 )   PDF(664KB) ( 2 )   Vanillyl alcohol, which is made up of an aromatic ring, an alcoholic hydroxyl group, a phenolic hydroxyl group and a methoxy group, was selected as the model molecule of lignin. Various carbon materials supported Pd catalysts were chosen to catalyze the HDO of vanillyl alcohol. The catalysts were characterized via TEM, TPD, XRD, XPS and CO-chemisorption. It was found that different carbon materials could obviously influence the particle sizes, dispersion and distribution of Pd or PdO particles. Palladium and carbon can synergistically catalyze the room-temperature HDO of vanillyl alcohol even at room temperature, and the carboxyl group was found to be the effective active acid site during the reaction. Possible reaction mechanism was also proposed. The existence of the effective active acid sites on the carbon supports could obviously lower the reaction temperature without decreasing the selectivity, as a result, making the production of renewable fuels by HDO much more economically feasible, which is of much importance.

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Fabrication and characterization of Fe3O4@SiO2@TiO2@Ho nanostructures as a novel and highly efficient photocatalyst for degradation of organic pollution Sobhan Mortazavi-Derazkola, Masoud Salavati-Niasar i, Omid Amir i, Ali Abbasi 2017, 26(1): 17-23.  DOI: 10.1016/j.jechem.2016.10.015 摘要 ( 5072 )   PDF(645KB) ( 2 )   In this work we synthesize a novel and highly efficient photocatalyst for degradation of methyl orange and rhodamine B. In addition, a new method for synthesis of Fe3O4@SiO2@TiO2@Ho magnetic core-shell nanoparticles with spherical morphology is proposed. The crystal structures, morphology and chemical properties of the as-synthesized nanoparticles were characterized using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDS), X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy (DRS) and vibrating sample magnetometer (VSM) techniques. The photocatalytic activity of Fe3O4@SiO2@TiO2@Ho was investigated by degradation of methyl orange (MO) as cationic dye and rhodamine B (RhB) as anionic dye in aqueous solution under UV/vis irradiation. The results indicate that about 92.1% of RhB and 78.4% of MO were degraded after 120 and 150 min, respectively. These degradation results show that Fe3O4@SiO2@TiO2@Ho nanoparticles are better photocatalyst than Fe3O4@SiO2@TiO2 for degradation of MO and RhB. As well as, the catalyst shows high recovery and stability even after several separation cycles.

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Synthesis of amorphous manganese borohydride in the (NaBH4-MnCl2) system, its hydrogen generation properties and crystalline transformation during solvent extraction Robert A. Varin, Deepak K. Mattar, Amirreza Shirani Bidabadi, Marek Polanski 2017, 26(1): 24-34.  DOI: 10.1016/j.jechem.2016.08.011 摘要 ( 4072 )   PDF(758KB) ( 2 )   The mixture of (2NaBH4+MnCl2) was ball milled in a magneto-mill. No gas release was detected. The XRD patterns of the ball milled mixture exhibit only the Bragg diffraction peaks of the NaCl-type salt which on the basis of the present X-ray diffraction results and the literature is likely to be a solid solution Na(Cl)x(BH4)(1-x), possessing a cubic NaCl-type crystalline structure. No presence of any crystalline hydride was detected by powder X-ray diffraction which clearly shows that NaBH4 in the initial mixture must have reacted with MnCl2 forming a NaCl-type by-product and another hydride that does not exhibit X-ray Bragg diffraction peaks. Mass spectrometry (MS) of gas released from the ball milled mixture during combined MS/thermogravimetric analysis (TGA)/differential scanning calorimetry (DSC) experiments, confirms mainly hydrogen (H2) with a small quantity of diborane gas, B2H6. The Fourier transform infra-red (FT-IR) spectrum of the ball milled (2NaBH4+MnCl2) is quite similar to the FT-IR spectrum of crystalline manganese borohydride, c-Mn(BH4)2, synthesized by ball milling, which strongly suggests that the amorphous hydride mechano-chemically synthesized during ball milling could be an amorphous manganese borohydride. Remarkably, the process of solvent filtration and extraction at 42℃, resulted in the transformation of mechano-chemically synthesized amorphous manganese borohydride to a nanostructured, crystalline, c-Mn(BH4)2 hydride.

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Preparation of active carbons from corn stalk for butanol vapor adsorption Yuhe Cao, Keliang Wang, Xiaomin Wang, Zhengrong Gu, Tyler Ambrico, William Gibbons, Qihua Fan, Al-Ahsan Talukder 2017, 26(1): 35-41.  DOI: 10.1016/j.jechem.2016.08.009 摘要 ( 3808 )   PDF(298KB) ( 4 )   Active carbons (ACs) were prepared through chemical activation of biochar from whole corn stalk (WCS) and corn stalk pith (CSP) at varying temperatures using potassium hydroxide as the activating agent. ACs were characterized via pore structural analysis and scanning electron microscopy (SEM). These adsorbents were then assessed for their adsorption capacity for butanol vapor. It was found that WCS activated at 900℃ for 1 h (WCS-900) had optimal butanol adsorption characteristics. The BET surface area and total pore volume of the WCS-900 were 2330 m2/g and 1.29 cm3/g, respectively. The dynamic adsorption capacity of butanol vapor was 410.0 mg/g, a 185.1% increase compared to charcoal-based commercial AC (143.8 mg/g).

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Hydrogen production through glycerol steam reforming using Co catalysts supported on SBA-15 doped with Zr, Ce and La Alicia Carrero, Arturo J. Vizcaíno, José A. Calles, Lourdes García-Moreno 2017, 26(1): 42-48.  DOI: 10.1016/j.jechem.2016.09.001 摘要 ( 4079 )   PDF(451KB) ( 4 )   The steam reforming of glycerol has been studied at 500 and 600℃ using Co/SBA-15 and Co/M/SBA-15 (M:Zr, Ce, or La) promoted catalysts. The prepared materials were characterized by inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray powder diffraction (XRD), hydrogen temperatureprogramed reduction (H2-TPR), ammonia temperature-programed desorption (NH3-TPD), nitrogen physisorption analysis (N2-BET), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The incorporation of promoters like Zr, Ce and La on SBA-15 support and successive Co impregnation leaded to smaller cobalt crystallites improving metaldispersion. Besides, stronger metal-support interactions between Co species and M/SBA-15 supports were observed. Thanks to the incorporation of Zr, La and mainly Ce, promoted catalysts present higher glycerol conversion than Co/SBA-15 along 5 h of time on stream. Besides, at 600℃, Co/M/SBA-15 (M:Zr, Ce, or La) catalysts produce higher hydrogen amounts than Co/SBA-15.

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Facile synthesis of high electrical conductive CoP via solid-state synthetic routes for supercapacitors Yumei Hu, Maocheng Liu, Qingqing Yang, Lingbin Kong, Long Kang 2017, 26(1): 49-55.  DOI: 10.1016/j.jechem.2016.10.001 摘要 ( 5836 )   PDF(542KB) ( 2 )   Co-P precursor was prepared by a mechanical alloying method and then is controlled to synthesis of CoP phase through an annealing method. The optimal conditions of ball milling and annealing temperature are investigated. The CoP exhibits higher electrical conductivity than graphite and cobalt oxide, showing excellent pseudocapacitive properties due its high electrical conductivity which can result in a fast electron transfer in high rate charge-discharge possess. The as-obtained CoP electrode achieves a high specific capacitance of 447.5 F/g at 1 A/g, and displays an excellent rate capability as well as good cycling stability. Besides, the asymmetric supercapacitor (ASC) based on the CoP as the positive electrode and activated carbon (AC) as the negative electrode was assembled and displayed a high rate capability (60% of the capacitance is retained when the current density increased from 1 A/g to 12 A/g), excellent cycling stability (96.7% of the initial capacitance is retained after 5000 cycles), and a superior specific energy of 19 Wh/kg at a power density of 350.8 W/kg. The results suggest that the CoP electrode materials have a great potential for developing high-performance electrochemical energy storage devices.

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KOH activated carbon derived from biomass-banana fibers as an efficient negative electrode in high performance asymmetric supercapacitor Chaitra K, Vinny R T, Sivaraman P, Narendra Reddy, Chunyan Hu, Krishna Venkatesh, Vivek C S, Nagaraju N, Kathyayini N 2017, 26(1): 56-62.  DOI: 10.1016/j.jechem.2016.07.003 摘要 ( 4322 )   PDF(560KB) ( 4 )   Here we demonstrate the fabrication, electrochemical performance and application of an asymmetric supercapacitor (AS) device constructed with β-Ni(OH)2/MWCNTs as positive electrode and KOH activated honeycomb-like porous carbon (K-PC) derived from banana fibers as negative electrode. Initially, the electrochemical performance of hydrothermally synthesized β-Ni(OH)2/MWCNTs nanocomposite and K-PC was studied in a three-electrode system using 1 M KOH. These materials exhibited a specific capacitance (Cs) of 1327 F/g and 324 F/g respectively at a scan rate of 10 mV/s. Further, the AS device i.e., β-Ni(OH)2/MWCNTs//K-PC in 1 M KOH solution, demonstrated a Cs of 156 F/g at scan rate of 10 mV/s in a broad cell voltage of 0-2.2 V. The device demonstrated a good rate capability by maintaining a Cs of 59 F/g even at high current density (25 A/g). The device also offered high energy density of 63 Wh/kg with maximum power density of 5.2 kW/kg. The AS device exhibited excellent cycle life with 100% capacitance retention at 5000th cycle at a high current density of 25 A/g. Two AS devices connected in series were employed for powering a pair of LEDs of different colors and also a mini fan.

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Nitrogen-doped cobalt nanoparticles/nitrogen-doped plate-like ordered mesoporous carbons composites as noble-metal free electrocatalysts for oxygen reduction reaction Vincent Mirai Bau, Xiangjie Bo, Liping Guo 2017, 26(1): 63-71.  DOI: 10.1016/j.jechem.2016.07.005 摘要 ( 4614 )   PDF(682KB) ( 0 )   In this work, nitrogen-doped cobalt nanoparticles/nitrogen-doped plate-like ordered mesoporous carbons (N/Co/OMCs) were used as noble-metal free electrocatalysts with high catalytic efficiency. Compared with OMCs with long channel length, due to more entrances for catalytic target accessibility and a short pathway for rapid diffusion, the utilization efficiency of cobalt nanoparticles inside the plate-like OMCs with short pore length is well improved, which can take full advantage of porous structure in electrocatalysis and increase the utilization of catalysts. The active sites in N/Co/OMCs for oxygen reduction reaction (ORR) are highly exposed to oxygen molecule, which results in a high activity for ORR. By combination of the catalytic properties of nitrogen dopant, incorporation of Co nanoparticles, and structural properties of OMCs, the N/Co/plate-like OMCs are highly active noble-metal free catalysts for ORR in alkaline solution.

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Analysis of silicon-based integrated photovoltaic-electrochemical hydrogen generation system under varying temperature and illumination Vishwa Bhatt, Brijesh Tripathi, Pankaj Yadav, Manoj Kumar 2017, 26(1): 72-80.  DOI: 10.1016/j.jechem.2016.09.006 摘要 ( 3764 )   PDF(859KB) ( 1 )   Last decade witnessed tremendous research and development in the area of photo-electrolytic hydrogen generation using chemically stable nanostructured photo-cathode/anode materials. Due to intimately coupled charge separation and photo-catalytic processes, it is very difficult to optimize individual components of such system leading to a very low demonstrated solar-to-fuel efficiency (SFE) of less than 1%. Recently there has been growing interest in an integrated photovoltaic-electrochemical (PV-EC) system based on GaAs solar cells with the demonstrated SFE of 24.5% under concentrated illumination condition. But a high cost of GaAs based solar cells and recent price drop of poly-crystalline silicon (pc-Si) solar cells motivated researchers to explore silicon based integrated PV-EC system. In this paper a theoretical framework is introduced to model silicon-based integrated PV-EC device. The theoretical framework is used to analyze the coupling and kinetic losses of a silicon solar cell based integrated PV-EC water splitting system under varying temperature and illumination. The kinetic loss occurs in the range of 19.1%-27.9% and coupling loss takes place in the range of 5.45%-6.74% with respect to varying illumination in the range of 20-100 mW/cm2. Similarly, the effect of varying temperature has severe impact on the performance of the system, wherein the coupling loss occurs in the range of 0.84%-21.51% for the temperature variation from 25 to 50℃.

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Melamine modified carbon felts anode with enhanced electrogenesis capacity toward microbial fuel cells Yang'en Xie, Zhaokun Ma, Huaihe Song, Zachary A. Stoll, Pei Xu 2017, 26(1): 81-86.  DOI: 10.1016/j.jechem.2016.11.020 摘要 ( 3971 )   PDF(357KB) ( 0 )   Surface electropositivity and low internal resistance are important factors to improve the anode performance in microbial fuel cells (MFCs). Nitrogen doping is an effective way for the modification of traditional carbon materials. In this work, heat treatment and melamine were used to modify carbon felts to enhance electrogenesis capacity of MFCs. The modified carbon felts were characterized using X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), atomic force microscopy (AFM) and malvern zeta potentiometer. Results show that the maximum power densities under heat treatment increase from 276.1 to 423.4 mW/m2 (700℃) and 461.5 mW/m2 (1200℃) and further increase to 472.5 mW/m2 (700℃) and 515.4 mW/m2 (1200℃) with the co-carbonization modification of melamine. The heat treatment reduces the material resistivity, improves the zeta potential which is beneficial to microbial adsorption and electron transfer. The addition of melamine leads to the higher content of surface pyridinic and quaternary nitrogen and higher zeta potential. It is related to higher MFCs performance. Generally, the melamine modification at high temperature increases the feasibility of carbon felt as MFCs's anode materials.

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Molecular pore-wall engineering of mesozeolitic conjugated polymers for photoredox hydrogen production with visible light Mingwen Zhang, Jinshui Zhang, Yan Chen, Xinchen Wang 2017, 26(1): 87-92.  DOI: 10.1016/j.jechem.2016.07.004 摘要 ( 5525 )   PDF(458KB) ( 3 )   A chemical protocol based on molecular engineering of polymeric matrix is developed for the chemical optimization of ordered mesoporous carbon nitride (OMCN) in this study to address the concerns on the serious nanostructure-induced semiconductive defects, in particular the remarkable hypsochromic shift of absorption threshold and the increased excition dissociation energy. Physical characterizations demonstrate that the successful incorporation of 3-aminothiophene-2-carbonitrile (ATCN) aromatic donor in OMCN matrix can efficiently extend the π-conjugated system, red-shift the optical absorption toward longer wavelengths and promote exciton splitting, thus well overcoming the serious semiconductive defects. In addition, the unique structural benefits of OMCN, such as the well-orientated nanoarchitectures with large specific surface area and uniform nanosized pore, have been well remained in ATCN-modified sample (OMCNA) via adjusting the ATCN/cyanamide molar ratio to minimize the unavoidable matrix disturbance. Hence, an obviously enhanced photocatalytic activity toward H2 evolution and selective oxidation of alcohols are obtained on optimized OMCNA samples, greatly underlining the advantage of molecular engineering in supporting nanostructured photocatalysts.

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Carbon dioxide reforming of methane over mesoporous nickel aluminate/γ-alumina composites Li Zhang, Xueguang Wang, Xingfu Shang, Mingwu Tan, Weizhong Ding, Xionggang Lu 2017, 26(1): 93-100.  DOI: 10.1016/j.jechem.2016.08.001 摘要 ( 6813 )   PDF(637KB) ( 1 )   A series of xNiAl2O4/γ-Al2O3 composites with various Ni contents have been prepared via one-step partial hydrolysis of metal nitrate salts in the absence of surfactants and used for carbon dioxide reforming of methane. The characterization results demonstrated that the NiAl2O4/γ-Al2O3 materials possessed mesoporous structures of uniform pore sizes; and the Ni2+ ions were completely reacted with alumina to NiAl2O4 spinel in the matrices using N2 sorption, XRD, TEM, and XPS. The NiAl2O4/γ-Al2O3 materials exhibited excellent catalytic properties and superior long-term stability for carbon dioxide reforming of methane. The effects of Ni content on the intrinsic activities and the amounts of coke disposition of the xNiAl2O4/γ-Al2O3 catalysts were discussed in detail for the carbon dioxide reforming of methane. The results revealed that the Ni particle sizes did not affect the intrinsic activity of metallic Ni, but smaller Ni particles could reduce the rate of coke deposition.

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Synthesis and electrochemical properties of dual doped spinels LiNixAlyMn2-x-yO4 via facile novel chelated sol-gel method as possible cathode material for lithium rechargeable batteries R. Thirunakaran, Gil Hwan Lew, Won-Sub Yoon 2017, 26(1): 101-114.  DOI: 10.1016/j.jechem.2016.08.006 摘要 ( 3599 )   PDF(1135KB) ( 5 )   LiMn2O4 and LiNixAly Mn2-x-yO4 (x=0.50; y=0.05-0.50) powders have been synthesized via facile sol-gel method using Behenic acid as active chelating agent. The synthesized samples are subjected to physical characterizations such as thermo gravimetric analysis (TG/DTA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and electrochemical studies viz., galvanostatic cycling properties, electrochemical impedance spectroscopy (EIS) and differential capacity curves (dQ/dE). Finger print XRD patterns of LiMn2O4 and LiNixAlyMn2-x-yO4 fortify the high degree of crystallinity with better phase purity. FESEM images of the undoped pristine spinel illustrate uniform spherical grains surface morphology with an average particle size of 0.5 μm while Ni doped particles depict the spherical grains growth (50 nm) with ice-cube surface morphology. TEM images of the spinel LiMn2O4 shows the uniform spherical morphology with particle size of (100 nm) while low level of Al-doping spinel (LiNi0.5Al0.05Mn1.45O4) displaying cloudy particles with agglomerated particles of (50 nm). The LiMn2O4 samples calcined at 850℃ deliver the discharge capacity of 130 mAh/g in the first cycle corresponds to 94% columbic efficiency with capacity fade of 1.5 mAh/g/cycle over the investigated 10 cycles. Among all four dopant compositions investigated, LiNi0.5Al0.05Mn1.45O4 delivers the maximum discharge capacity of 126 mAh/g during the first cycle and shows the stable cycling performance with low capacity fade of 1 mAh/g/cycle (capacity retention of 92%) over the investigated 10 cycles. Electrochemical impedance studies of spinel LiMn2O4 and LiNi0.5Al0.05Mn1.45O4 depict the high and low real polarization of 1562 and 1100 Ω.

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Efficient production of ethyl levulinate from cassava over Al2(SO4)3 catalyst in ethanol-water system Jin Tan, Qiying Liu, Lungang Chen, Tiejun Wang, Longlong Ma, Guanyi Chen 2017, 26(1): 115-120.  DOI: 10.1016/j.jechem.2016.08.004 摘要 ( 3452 )   PDF(377KB) ( 1 )   One-pot achievement of ethyl levulinate from cassava was conducted in ethanol-water system over several simple sulfate salt catalysts. Al2 (SO4)3 catalyst had the best performance in synthesizing ethyl levulinate comparing with those of a series of sulfate salts. The highest yields of ethyl levulinate was up to 39.27% as well as 7.78% levulinate acid when cassava was catalyzed in ethanol medium by adding 10 wt% water. 13C and 1H NMR spectroscopic investigations confirmed that isomerization of glucose to fructose over Al2(SO4)3 catalyst is an important step in producing ethyl levulinate and levulinate acid. Due to aggregations of Al3+ under hydrothermal conditions, tiny amount of Al3+ were detected in filtrate at the percentage of 0.32% even if in absolute water. Brønsted and Lewis acids could improve the yield of ethyl levulinate and levulinate acid by synergistic effect. All results suggested that Al2(SO4)3 was a simple and efficient catalyst for ethyl levulinate and levulinate acid production.

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Effect of the pore length and orientation upon the electrochemical capacitive performance of ordered mesoporous carbons Anran Huang, Jingwang Yan, Hongzhang Zhang, Xianfeng Li, Huamin Zhang 2017, 26(1): 121-128.  DOI: 10.1016/j.jechem.2016.08.005 摘要 ( 4701 )   PDF(460KB) ( 1 )   By utilizing hard template method to adjust the mesopore length, and alkali activation to generate micropores, two hierarchical porous carbons (HPCs) were prepared. With controlling of their mesopore length and the activation conditions, the complex system composed by HPCs and electrolyte was simplified and the effect of mesopore length on the performance of HPCs as electrodes in supercapacitors was investigated. It is found that with the mesopore length getting smaller, the ordered area gets smaller and the aggregation occurs, which is caused by the high surface energy of small grains. HPC with long pores (HPCL) exhibits a donut-like morphology with well-defined ordered mesopores and a regular orientation while in HPC with short pores (HPCS), short mesopores are only orderly distributed in small regions. Longer ordered channels form unobstructed ways for ions transport in the particles while shorter channels, only orderly distributed in small areas, results in blocked paths, which may hinder the electrolyte ions transport. Due to the unobstructed structure, HPCL exhibits good rate capability with a capacitance retention rate over 86% as current density increasing from 50 mA/g to 1000 mA/g. The specific capacitance of HPCL derived from the cyclic voltammetry test at 10 mV/s is up to 201.72 F/g, while the specific capacitance of HPCS is only 193.65 F/g.

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Development of flexible zinc-air battery with nanocomposite electrodes and a novel separator Zhiqian Wang, Xianyang Meng, Zheqiong Wu, Somenath Mitra 2017, 26(1): 129-138.  DOI: 10.1016/j.jechem.2016.08.007 摘要 ( 4582 )   PDF(1041KB) ( 7 )   In this paper, we present the development of flexible zinc-air battery. Multiwalled carbon nanotubes (MWCNTs) were added into electrodes to improve their performance. It was found that MWCNTs were effective conductive additive in anode as they bridged the zinc particles. Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) was applied as a co-binder to enhance both the conductivity and flexibility. A poly (acrylic acid) (PAA) and polyvinyl alcohol (PVA) coated paper separator was used to enhance the battery performance where the PVP-PAA layer facilitated electrolyte storage. The batteries remained functional under bending conditions and after bending. Multiple design optimizations were also carried out for storage and performance purposes.

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Fabrication of a nano-sized ZSM-5 zeolite with intercrystalline mesopores for conversion of methanol to gasoline Tingjun Fu, Jiangwei Chang, Juan Shao, Zhong Li 2017, 26(1): 139-146.  DOI: 10.1016/j.jechem.2016.09.011 摘要 ( 5195 )   PDF(483KB) ( 3 )   Carbon deposition during methanol to hydrocarbons leads to the quick deactivation of ZSM-5 catalyst and it is one of the major problems for this technology. Decreasing the crystal size or introducing mesopores into ZSM-5 zeolites can improve its diffusion property and decrease the coke formation. In this paper, nano-sized ZSM-5 zeolite with intercrystalline mesopores combining the mesoporous and nanosized structure was fabricated. For comparison, the mesoporous ZSM-5 and nano-sized ZSM-5 were also prepared. These catalyst samples were characterized by XRD, BET, NH3-TPD, TEM, Py-IR and TG techniques and used on the conversion of methanol to gasoline in a fixed-bed reactor at T=405℃, WHSV=4.74 h-1 and P=1.0 MPa. It was found that the external surface area of the nano-sized ZSM-5 zeolite with intercrystalline mesopores reached 104 m2/g, larger than that of mesoporous ZSM-5 (66 m2/g) and nanosized ZSM-5 (76 m2/g). Catalytic lifetime of the nano-sized ZSM-5 zeolite with intercrystalline mesopores was 93 h, which was only longer than that of mesoporous ZSM-5 (86 h), but shorter than that of nanosized ZSM-5 (104 h). Strong acidity promoted the coke formation and thus decreased the catalytic lifetime of the nano-sized ZSM-5 zeolite with intercrystalline mesopores though it presented large external surface that could improve the diffusion property. The special zeolite catalyst was further dealuminated to decrease the strong acidity. After this, its coke formation rate was slowed and catalytic lifetime was prolonged to 106 h because of the large external surface area and decreased weak acidity. This special structural zeolite is a potential catalyst for methanol to gasoline reaction.

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Protonated and layered transition metal oxides as solid acids for dehydration of biomass-based fructose into 5-hydroxymethylfurfural Jiawei Zhong, Yuanyuan Guo, Jinzhu Chen 2017, 26(1): 147-154.  DOI: 10.1016/j.jechem.2016.09.010 摘要 ( 5117 )   PDF(797KB) ( 1 )   A serial of protonated and layered transition metal oxides, including layered HTaWO6, HNbMoO6 as well as HNbWO6, were synthesized by solid-state reaction and ion-exchange. The layered HTaWO6 has been systematically studied as a solid acid to realize the dehydration of fructose to 5-hydroxymethylfurfural (HMF). The transition metal oxide samples were characterized with ICP-OES, EDS, XRD, XPS, SEM, TGA, FT-IR, N2 adsorption-desorption and NH3-TPD. The influential factors such as reaction temperature, reaction time, solvent, catalyst amount and substrate concentration were deeply investigated. The optimized fructose conversion rate of 99% with HMF yield of 67% were achieved after 30 min at 140℃ in dimethylsulfoxide.

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Reaction of nitrous oxide with methane to synthesis gas: A thermodynamic and catalytic study Naseer A. Khan, Eric M. Kennedy, Bogdan Z. Dlugogorski, Adesoji A. Adesina, Michael Stockenhuber 2017, 26(1): 155-162.  DOI: 10.1016/j.jechem.2016.10.002 摘要 ( 6721 )   PDF(317KB) ( 0 )   The aim of the present study is to explore the coherence of thermodynamic equilibrium predictions with the actual catalytic reaction of CH4 with N2O, particularly at higher CH4 conversions. For this purpose, key process variables, such as temperature (300℃-550℃) and a molar feed ratio (N2O/CH4=1, 3, and 5), were altered to establish the conditions for maximized H2 yield. The experimental study was conducted over the Co-ZSM-5 catalyst in a fixed bed tubular reactor and then compared with the thermodynamic equilibrium compositions, where the equilibrium composition was calculated via total Gibbs free energy minimization method. The results suggest that molar feed ratio plays an important role in the overall reaction products distribution. Generally for N2O conversions, and irrespective of N2O/CH4 feed ratio, the thermodynamic predictions coincide with experimental data obtained at approximately 475℃-550℃, indicating that the reactions are kinetically limited at lower range of temperatures. For example, theoretical calculations show that the H2 yield is zero in presence of excess N2O (N2O/CH4=5). However over a Co-ZSM-5 catalyst, and with a same molar feed ratio (N2O/CH4) of 5, the H2 yield is initially 10% at 425℃, while above 450℃ it drops to zero. Furthermore, H2 yield steadily increases with temperature and with the level of CH4 conversion for reactions limited by N2O concentration in a reactant feed. The maximum attainable (from thermodynamic calculations and at a feed ratio of N2O/CH4=3) H2 yield at 550℃ is 38%, whereas at same temperature and over Co-ZSM-5, the experimentally observed yield is about 19%. Carbon deposition on Co-ZSM-5 at lower temperatures and CH4 conversion (less than 50%) was also observed. At higher temperatures and levels of CH4 conversion (above 90%), the deposited carbon is suggested to react with N2O to form CO2.

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Influences of the adsorption state of catalyst on the performance of DS-PEC for visible light driven water splitting Linlin Zhang, Yan Gao, Xin Ding 2017, 26(1): 163-167.  DOI: 10.1016/j.jechem.2016.09.003 摘要 ( 5186 )   PDF(380KB) ( 0 )   Adsorption state of catalyst on photoanode is an important factor on influencing the performance of dye-sensitized photoelectrochemical cells (DS-PECs) for water splitting. Photoanode TiO2 (1+2) was assembled with Ru(bpy)3 phosphoric acid derivative (complex 1) as photosensitizer and complex 2 as water oxidation catalyst to compare with photoanode TiO2 (1+3). The photocurrent density of photoanode TiO2 (1+3) with catalyst 3 synthesized with only one end fixing on the surface of TiO2 is about four-fold of the photoanode assembled with catalyst 2 fixing with two claws on the surface of TiO2. The phenomenon should be caused by the littery arrangement and shorter distance of catalyst 2 from the active center of catalyst to TiO2 on the surface of semiconductor which led to lowly efficient electron transfer.

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Ti/(Ti,Cr)N/CrN multilayer coated 316L stainless steel by arc ion plating as bipolar plates for proton exchange membrane fuel cells Shengli Wang, Ming Hou, Qing Zhao, Yongyi Jiang, Zhen Wang, Huizhe Li, Yu Fu, Zhigang Shao 2017, 26(1): 168-174.  DOI: 10.1016/j.jechem.2016.09.004 摘要 ( 4344 )   PDF(510KB) ( 5 )   Arc ion plating (AIP) is applied to form Ti/(Ti,Cr)N/CrN multilayer coating on the surface of 316L stainless steel (SS316L) as bipolar plates for proton exchange membrane fuel cells (PEMFCs). The characterizations of the coating are analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Interfacial contact resistance (ICR) between the coated sample and carbon paper is 4.9 mΩcm2 under 150 N/cm2, which is much lower than that of the SS316L substrate. Potentiodynamic and potentiostatic tests are performed in the simulated PEMFC working conditions to investigate the corrosion behaviors of the coated sample. Superior anticorrosion performance is observed for the coated sample, whose corrosion current density is 0.12 μA/cm2. Surface morphology results after corrosion tests indicate that the substrate is well protected by the multilayer coating. Performances of the single cell with the multilayer coated SS316L bipolar plate are improved significantly compared with that of the cell with the uncoated SS316L bipolar plate, presenting a great potential for PEMFC application.

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NiCo2O4 decorated PANI-CNTs composites as supercapacitive electrode materials Gunjana Chaudhary, Ashok K. Sharma, Preetam Bhardwaj, Kamal Kant, Indu Kaushal, Ajay K. Mishra 2017, 26(1): 175-181.  DOI: 10.1016/j.jechem.2016.09.013 摘要 ( 6240 )   PDF(1125KB) ( 6 )   Hierarchical NiCo2O4/PANI/CNTs hybrid composites were designed and fabricated having a layer of NiCo2O4 on the surface of PANI encapsulated CNTs with different morphologies. Physicochemical attributes of the synthesized composites were examined by FTIR, UV-visible and X-ray diffraction (XRD) techniques. Morphological aspects were evaluated by field-emission scanning microscopy (FESEM), electron diffraction spectroscopy (EDS), high resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) studies. Electrochemical measurements revealed an improved specific capacitance of 2250 F/g at a scan rate of 5 mV/s and 2000 F/g at a current density of 1 A/g with good rate capability using a three-electrode system. These enhanced features are achieved from the well designed nanostructure and the synergistic contributions of individual components in the electrode material.

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Polyaniline-based electrocatalysts through emulsion polymerization: Electrochemical and electrocatalytic performances Shehnaz, Xuedan Song, Suzhen Ren, Ying Yang, Yanan Guo, Hongyu Jing, Qing Mao, Ce Hao 2017, 26(1): 182-192.  DOI: 10.1016/j.jechem.2016.11.013 摘要 ( 4008 )   PDF(956KB) ( 1 )   One of the major challenges associated with fuel cells is the design of highly efficient electrocatalysts to reduce the high overpotential of the oxygen reduction reaction (ORR). Here we report Polyaniline (PANI) based micro/nanomaterials with or without transition metals, prepared by the emulsion polymerization and subsequent heat treatment. PANI microspheres with the diameter of about 0.7 μm have been prepared in basic (NH3 solution) condition, using two different types of surfactant (CTAB, SDS) as the stabilizer, ammonium persulphate (APS) as oxidant with aniline/surfactants molar ratio at 1/1 under the hydrothermal treatment. PANI nanorods, Fe-PANI, and Fe-Co-PANI have been synthesized in acidic (HCl) medium with aniline/surfactants molar ratio at 1/2 and polymerization carried out without stirring for 24 h. Products mainly Fe-Co-PANI have shown high current density with increasing sweep rate and excellent specific capacitance 1753 F/g at the scan rate of 1 mV/s. Additionally, it has shown high thermal stability by thermogravimetric analysis (TGA). Fe-PANI has been investigated for excellent performance toward ORR with four electron selectivity in the basic electrolyte. The PANI-based catalysts from emulsion polymerization demonstrate that the method is valuable for making non-precious metal heterogeneous electrocatalysts for ORR or energy storage and conversion technology.

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Highly efficient and stable electrooxidation of methanol and ethanol on 3D Pt catalyst by thermal decomposition of In2O3 nanoshells Yuhang Xie, Hulin Zhang, Guang Yao, Saeed Ahmed Khan, Xiaojing Cui, Min Gao, Yuan Lin 2017, 26(1): 193-199.  DOI: 10.1016/j.jechem.2016.11.014 摘要 ( 5703 )   PDF(485KB) ( 4 )   In this paper In2O3 nanoshells have been synthesized via a facile hydrothermal approach. The nanoshells can be completely cracked into pony-size nanocubes by annealing, which are then used as a support of Pt catalyst for methanol and ethanol electrocatalytic oxidation. The prepared In2O3 and supportedPt catalysts (Pt/In2O3) were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), field effect scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). Cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry and electrochemical impedance spectroscopy (EIS) were carried out, indicating the excellent catalytic performance for alcohol electrooxidation can be achieved on Pt/In2O3 nanocatalysts due to the multiple active sites, high conductivity and a mass of microchannels and micropores for reactant diffusions arising from 3D frame structures compared with that on the Pt/C catalysts.

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Wormholelike mesoporous carbon supportedPtRu catalysts toward methanol electrooxidation Weifeng Liu, Xiaoping Qin, Xiongfu Zhang, Zhigang Shao, Baolian Yi 2017, 26(1): 200-206.  DOI: 10.1016/j.jechem.2016.08.003 摘要 ( 3556 )   PDF(775KB) ( 1 )   Wormholelike mesoporous carbons (WMCs) with three different pore diameters (Dp), namely WMC-F7 (Dp=8.5 nm), WMC-F30 (Dp=4.4 nm), and WMC-F0 (Dp=3.1 nm) are prepared via a modified sol-gel process. Then PtRu nanoparticles with the particle size (dPt) of ~3.2 nm supported on WMCs are synthesized with a modified pulse microwave-assisted polyol method. It is found that the pore diameter of WMCs plays an important role in the electrochemical activity of PtRu toward alcohol electrooxidation reaction. PtRu/WMC-F7 with Dp>2dPt exhibits the largest electrochemical surface area (ESA) and the highest activity toward methanol electrooxidation. With the decrease in Dp, PtRu/WMC-F30 and PtRu/WMC-F0 have much lower ESA and electrochemical activity, especially for the isopropanol electrooxidation with a larger molecular size. When Dp is more than twice dPt, the mass transfer of reactants and electrolyte are easier, and thus more PtRu nanoparticles can be utilized and the catalysts activity can be enhanced.