JOURNAL OF SOLID STATE ELECTROCHEMISTRY
·
2016
·Vol. 21
·期 2
·391-401
·
IF 2.327
Peng Meiling,Xu Wei,Cui Weihao,Wang Tao,Wang Sheng
This study reports the synthesis of octahedral Pd-Pt bimetallic alloy nanocrystals through a facile, one-pot, templateless, and seedless hydrothermal method in the presence of glucose and hexadecyl trimethyl ammonium bromide. The morphologies, compositions, and structures of the Pd-Pt nanocrystals were fully characterized by various physical techniques, thereby demonstrating their highly alloying octahedral nanostructures. The formation or growth mechanism of the Pd-Pt bimetallic alloy nanocrystals was explored and is discussed here based on the experimental observations. In addition, the synthesized Pd-Pt nanocrystals were applied to the methanol oxidation reaction (MOR) in alkaline media, which proved that the as-prepared catalysts exhibit enhanced electrocatalytic activity for MOR. Pd 1 Pt 3 exhibited the best stability and durability, and its mass activity was 3.4 and 5.2 times greater than those of Pt black and Pd black catalysts, respectively. The facile synthetic process and excellent catalytic performance of the as-prepared catalysts demonstrate that they have the potential to be used in direct methanol fuel cell techniques.
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JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2016
·Vol. 28
·期 1
·768-772
·
IF 1.798
Shen Yongzhen,Ren Xiaohui,Qi Xiang,Zhou Jie,Xu Guanghua,Huang Zongyu,Zhong Jianxin
Two-dimensional NiSe 2 nanosheets arrange on three-dimensional carbon cloths (CC) have been synthesized through a facile two-step hydrothermal process. The as-prepared NiSe 2 /CC photoelectrode demonstrates outstanding photoelectrochamical (PEC) performance. Subsequently, a series of characterization techniques including X-ray diffraction and Raman spectra are carried out and confirm a well crystalline NiSe 2 /CC. Additional morphological and microstructural tests depict large-scale NiSe 2 nanosheets are uniformly aligned on the basement of conductive carbon cloth. The PEC measurements show the steady photocurrent density can be effectively raised from 10 to 600 μA/cm 2 when bias potential increases from 0 to 0.5 V, which is proposed to be attributed to the adequate exposure of active sites and reduction of surface contact resistance provided by carbon cloth. The structure and performances of hydrothermal synthesized NiSe 2 /CC suggest promising applications in the field of PEC hydrogen production.
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JOURNAL OF FLUORESCENCE
·
2017
·Vol. 28
·期 1
·269-276
·
IF 1.461
Zhao Chunxi,Jiao Yang,Hua Jianhao,Yang Jian,Yang Yaling
Nitrogen-doped carbon quantum dots (N-CQDs) were synthesized though a facile, economical and straightforward hydrothermal method by using polyacrylamide as both carbon and nitrogen sources. The as-prepared N-CQDs offered high quantum yield of 23.1%, exhibited good water solubility and fluorescence properties. Moreover, the N-CQDs can be used as effective probes for sensitive and selective detection of dopamine. Fluorescence of N-CQDs was effectively quenched after the addition of dopamine owing to dopamine would be transformed into dopamine-quinone under alkaline conditions. A good linear relationship between fluorescence quenching and the concentration of dopamine in the range 0.1–200 μM was obtained with a low detection limit of 0.05 μM. The proposed method showed high selectivity for dopamine in the presence of potential interfering species. Moreover, this method was successfully applied to the determination of DA in urine sample with satisfactory recoveries.
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ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2017
·Vol. 24
·期 31
·24562-24571
·
IF 2.741
Chen Zhiliang,Lu Shengyong,Mao Qiongjing,Buekens Alfons,Wang Yuting,Yan Jianhua
Mechanochemistry (MC) exerts extraordinary degradation and decomposition effects on many chlorinated, brominated, and even fluorinated persistent organic pollutants (POPs). However, its application is still limited by inadequate study of its reaction kinetic aspects. In the present work, the ball motion and energy transfer in planetary ball mill are investigated in some detail. Almost all milling parameters are summarised in a single factor—total effective impact energy. Furthermore, the MC kinetic between calcium oxide/Al and hexachlorobenzene is well established and modelled. The results indicate that total effective impact energy and reagent ratio are the two factors sufficient for describing the MC degradation degree of POPs. The reaction rate constant only depends on the chemical properties of reactants, so it could be used as an important index to appraise the quality of MC additives. This model successfully predicts the reaction rate for different operating conditions, indicating that it could be suitably applied for conducting MC reactions in other reactors.
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Frontiers of Chemical Science and Engineering
·
2017
·Vol. 11
·期 4
·613-623
·
IF 1.712
Tang Honggui,Li Shuangshuang,Gong Dandan,Guan Yi,Liu Yuan
Carbon deposition and sintering of active components such as nano particles are great challenges for Ni-based catalysts for CO methanation to generate synthetic natural gas from syngas. Facing the challenges, bimetallic catalysts with different Fe content derived from layered double hydroxide containing Ni, Fe, Mg, Al elements were prepared by co-precipitation method. Nanoparticles of Ni-Fe alloy were supported on mixed oxides of aluminium and magnesium after calcination and reduction. The catalysts were characterized by Brunner-Emmett-Teller (BET), X-ray diffraction, hydrogen temperature programmed reduction, inductively coupled plasma, X-ray photoelectron spectroscopy, transmission electron microscopy and thermogravimetric techniques, and their catalytic activity for CO methanation was investigated. The results show that the Ni-Fe alloy catalysts exhibit better catalytic performance than monometallic catalysts except for the Ni4Fe-red catalyst. The Ni2Fe-red catalyst shows the highest CO conversion (100% at 260–350 °C), as well as the highest CH 4 selectivity (over 95% at 280–350 °C), owing to the formation of Ni-Fe alloy. In stability test, the Ni2Fe-red catalyst exhibits great improvement in both anti-sintering and resistance to carbon formation compared with the Ni0Fe-red catalyst. The strong interaction between Ni and Fe element in alloy and surface distribution of Fe element not only inhibits the sintering of nanoparticles but restrains the formation of Ni clusters.
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CELLULOSE
·
2017
·Vol. 24
·期 11
·5187-5196
·
IF 3.417
Wei Chengzhuo,Fan Lingling,Rao Weida,Bai Zikui,Xu Weilin,Bao Haifeng,Xu Jie
Paper with color changes caused by applied electric voltages was fabricated by combining the electric heating feature of conductive polypyrrole (PPy) and the temperature response color-changing feature of thermochromic ink. Highly conductive PPy was deposited selectively on the graphite-coated side of the paper via electrochemical polymerization. Thermochromic ink was coated on the reverse side with white color. The conductive coatings were tightly covered on the paper due to the hydrogen bonding between the pyrrole rings and the hydroxyl groups of cellulose. The obtained paper could be heated to about 45 °C and change its color significantly under an applied voltage of 4 V.
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CELLULOSE
·
2017
·Vol. 24
·期 6
·2415-2425
·
IF 3.417
Sang Xiankui,Qin Chengrong,Tong Zhangfa,Kong Song,Jia Zhuan,Wan Guangcong,Liu Xinliang
2,2,6,6-Tetramethylpiperidine-1-oxyl radical (TEMPO) can selectively oxidize primary hydroxyl groups of cellulose to carboxyl groups. However, the depolymerization also occurs during the process. The kinetics and mechanism of carboxyl group formation on the surface of cellulose fiber oxidized by TEMPO/NaClO 2 /NaClO were discussed. The oxidization and depolymerization of cellulose occurred simultaneously, according to analysis of FTIR and 13 C CP/MAS NMR. The glucuronic acid and some small molecular fragments, formed by hydrolysis or β-elimination during the oxidation, are also discussed. The crystallization index increased and crystal size decreased, as shown by X-ray analysis. The degradation steps in the TEMPO/NaClO 2 /NaClO system was discussed, according to carbon conversion analyzed by 13 C CP/MAS NMR. The oxidation of cellulose can be described well by the kinetics model established based on the degradation of cellulose. It was found that temperature is one of the key parameters for controlling the oxdation and degradation level. The possible mechanism for oxidation of cellulose was composed.
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JOURNAL OF ELECTRONIC MATERIALS
·
2017
·Vol. 46
·期 7
·4676-4681
·
IF 1.579
Han Wensong
Third-generation hyperbranched polyester (HBPE3) was synthesized by stepwise polymerization with N , N -diethylol-3-amine methylpropionate as AB 2 monomer and pentaerythritol as core molecule. Then, Cu particles were prepared by reduction of copper nitrate with ascorbic acid in aqueous solution using HBPE3 as template. Finally, Cu/SiO 2 particles were prepared by coating silica on the surface of Cu particles. The structure and morphology of the samples were characterized by Fourier-transform infrared (FT-IR) spectrometry, x-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The results confirmed the formation of the silica coating on the surface of Cu and that the Cu/SiO 2 particles had spherical shape with particle size in the range of 0.8 μ m to 2 μ m. Compared with pure Cu, the synthesized Cu/SiO 2 core–shell particles exhibited better oxidation resistance at high temperature. Moreover, the oxidation resistance of the Cu/SiO 2 particles increased significantly with increasing tetraethyl orthosilicate (TEOS) concentration.
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Nanoscale Research Letters
·
2017
·Vol. 12
·期 1
·1-10
·
IF 2.833
Qin Yanyan,Cui Yanping,Tian Zhen,Wu Yangling,Li Yilian
Ag@AgCl core–shell nanowires were synthesized by oxidation of Ag nanowires with moderate FeCl 3 , which exhibited excellent photocatalytic activity for As(III) oxidation under visible light. It was proved that the photocatalytic oxidation efficiency was significantly dependent on the mole ratio of Ag:AgCl. The oxidation rate of As(III) over Ag@AgCl core–shell nanowires first increased with the decrease of Ag 0 percentage, up until the optimized synthesis mole ratio of Ag nanowires:FeCl 3 was 2.32:2.20, with 0.023 mg L −1 min −1 As(III) oxidation rate; subsequently, the oxidation rate dropped with the further decrease of Ag 0 percentage. Effects of the pH, ionic strength, and concentration of humic acid on Ag@AgCl photocatalytic ability were also studied. Trapping experiments using radical scavengers confirmed that h + and ·O 2
− acted as the main active species during the visible-light-driven photocatalytic process for As(III) oxidation. The recycling experiments validated that Ag@AgCl core–shell nanowires were a kind of efficient and stable photocatalyst for As(III) oxidation under visible-light irradiation.
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Waste and Biomass Valorization
·
2016
·Vol. 9
·期 1
·95-101
·
IF 0.915
Ning Liangmin,Liao Shengyun,Sun Yongfa,Yu Linhao,Tong Xinli
Abstract The catalytic synthesis of 2,5-diformylfuran (DFF) from 5-hydroxymethylfurfural (HMF) attracts extensive attention in the research of biomass conversion. However, it is a challenge to achieve high conversion of HMF under mild conditions with a heterogeneous catalyst, which can be easily separated and recycled. Herein, we report a novel cobalt-based catalyst (Co x O y -N@TiO 2 ) for the oxidation of HMF to DFF with 30 % aqueous tert -butyl hydroperoxide as the oxidant. A series of Co-based catalysts were prepared by a typical impregnation method, and detected by XRD, TEM and FT-IR techniques. Based on the experimental results of catalytic test, it is found that a 91 % conversion of HMF and 40 % selectivity of DFF was obtained with the Co x O y -N@TiO 2 catalyst at 80 °C within 5 h. In addition, the Co x O y -N@TiO 2 can be recycled up to five times without significant loss of activity. Graphical Abstract The efficient oxidation of 5-hydroxymethyl furfural, a biomass-derived platform compound, to produce 2,5-diformylfuran is achieved using Co x O y -N@TiO 2 catalyst under mild conditions.
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APPLIED BIOCHEMISTRY AND BIOTECHNOLOGY
·
2016
·Vol. 181
·期 3
·972-985
·
IF 1.606
Wu Hua-Lei,Zhang Jian-Dong,Zhang Chao-Feng,Fan Xiao-Jun,Chang Hong-Hong,Wei Wen-Long
Four uncharacterized ω-transaminases (ωTAs) from Pseudomonas putida NBRC 14164 have been identified and cloned from the pool of fully sequenced genomes. The genes were functionally expressed in Escherichia coli BL21, and the enzymes were purified and characterized. Four TAs showed highly ( S )-selective ωTA activity and converted ( S )-α-methylbenzylamine and pyruvate to acetophenone and l -Ala. The maximum activity of cloned enzymes was in the pH range of 8.0– 8.5 (Pp36420), 8.5 –9. 5 (Pp21050), 9 .0– 9.5 (PpspuC), and 9.5 –1 0 . 5 (PpbauA), and the optimal temperatures were at 35 °C (Pp36420, Pp21050, and PpspuC) and 50 °C (PpbauA), respectively, with K
M of 161.3 mM (Pp21050), 136.7 mM (PpbauA), 398.5 mM (Pp36420), and 130.9 mM (PpspuC) and yielding a catalytic efficiency k
cat / K
M of 0.015, 0.003, 0.012, and 0.023 mM −1 s −1 . Several racemic amines and amino alcohols were resolved by the cloned ωTAs; perfect conversions (48–50 %) were obtained by at least one enzyme, and the residual substrates were left with 97–99 % ee. Kinetic resolution of racemic phenylglycinol was done with PpspuC in a 100-mL scale. Enaniomeric excess of ( S )-phenylglycinol reached 99 % with 45 % isolated yield. The high enantioselectivity and large substrate spectra of the cloned PpTAs showed an attractive potency for biotechnology application in production of chiral amines and amino alcohols.
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JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2016
·Vol. 28
·期 3
·2867-2876
·
IF 1.798
Yu Libo,Li Zhen,Song Hai
Based on translucent TiO 2 nanotube (NT) film, CdS quantum dots (QDs) were anchored onto TiO 2 NT film using different linker molecules including thioglycolic acid (TGA), mercaptopropionic acid (MPA) and cysteine via hydrothermal method. The CdS QDs sensitized TiO 2 NT (CdS/TiO 2 NT) electrodes were constructed to quantum dots-sensitized solar cells (QDSSCs). The photovoltaic performance analysis results of the QDSSCs show that the linker molecule plays a significant role in the solar cell performance. The QDSSC using cysteine as linker molecule exhibits best power conversion efficiency than the other QDSSCs using TGA or MPA as linker molecules. The incident photon-to-current conversion efficiency (IPCE) and the electrochemical impedance spectroscopy (EIS) analysis results indicate that amino group of cysteine may has two aspects of the role to improve the power conversion efficiency of the QDSSC, one is that the good charge transfer properties of the cysteine might depend on the good donor–acceptor abilities of the free electron pair of the amino group, another is that distance between the TiO 2 NT and the CdS QDs could be slightly decreased due to the cysteine could anchor the CdS QDs via both amino and thiol group.
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