Journal of Materials Chemistry A
·
2017
·Vol. 5
·期 18
·8705-8713
·
IF 8.867
Hao Feng,Wenjun Ma,Zhong-Kai Cui,Xiaoyun Liu,Jinlou Gu,Shaoliang Lin,Qixin Zhuang
This study reports the synthesis of core/shell-structured hyperbranched aromatic polyamide functionalized graphene nanosheets-poly(p-phenylene benzobisoxazole) (GNs-HAP-PBO) nanocomposite films with improved dielectric properties and thermostability. PBO precursor polymer chains were grafted onto the ample amino-terminated GNs-HAP via in situ polymerization, and then the reduction of GNs-HAP and the intramolecular cyclization of PBO precursors were achieved through thermal treatment. The unique core/shell-structure is effective to prevent the aggregation of GNs and improves the dispersion of GNs in the GNs-HAP-PBO nanocomposites, forming microcapacitor networks in the matrix. The GNs-HAP-PBO nanocomposite films exhibit lower dielectric loss in comparison with solvothermally reduced graphene oxide/PBO nanocomposite films. At 1 kHz and 200 °C, a dielectric constant of 66.27 and a dielectric loss of 0.045 are observed in the GNs-HAP-PBO nanocomposite films with 2 wt% GNs-HAP. Moreover, the maximum energy density of the GNs-HAP-PBO nanocomposite films is up to 6 J cm−3 owing to the high breakdown strength (132.5 ± 9.3 kV mm−1). The GNs-HAP-PBO nanocomposite films with 2 wt% GNs-HAP also exhibit excellent tensile strength (125 MPa), Young's modulus (6.4 GPa), and high thermal stability (temperature of 5 wt% loss = 643 °C). This work demonstrates a promising strategic approach to fabricating high dielectric materials under extreme environments.
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高影响因子
Materials Science & Engineering C-Materials for Biological Applications
·
2017
·
IF 4.164
Yue Xu,Hang Gao,Yan Shen,Shigan Chai,Jinzhi Zhang,Qichao Zou
Novel Gemini quaternary ammonium salts (GQASs) with ester groups were synthesized. Cationic poly(styrene- co -butyl acrylate) (P(St- co -BA)) nanolatex was synthesized in the presence of GQASs as emulsifier. The structures of GQASs were characterized with Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy; the property of P(St- co -BA) nanolatex was characterized with dynamic light scattering. The results indicated that GQASs and P(St- co -BA) nanolatex with GQASs were successfully synthesized. GQASs, nanolatex, and the polymer films exhibited excellent antibacterial activities against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli . The GQASs performed even better than the corresponding single-stranded quaternary ammoniums. The antibacterial mechanism was also preliminarily studied, and longer, softer hydrophobic chains of GQAS had stronger antibacterial activity. The work provided a novel, simple approach for developing high-efficiency antibacterial polymer material with a low cost, which has broad biomaterial applications.
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高影响因子
ACS Applied Materials & Interfaces
·
2016
·
IF 7.145
Wenjie Yin,Lijie Bai,Yuzhen Zhu,Shuxian Zhong,Leihong Zhao,Zhengquan Li,Song Bai
The construction of a p-n heterojunction is an efficient strategy to resolve the limited light absorption and serious charge-carrier recombination in semiconductors and enhance the photocatalytic activity. However, the promotion effect is greatly limited by poor interfacial charge transfer efficiency as well as reduced redox ability of charge carriers. In this work, we demonstrate that the embedding of metal Pd into the interface between n-type C3N4 and p-type Cu2O can further enhance the interfacial charge transfer and increase the redox ability of charge carriers through the design of the C3N4-Pd-Cu2O stack nanostructure. The embedded Pd nanocubes in the stack structure not only trap the charge carriers from the semiconductors in promoting the electron–hole separation but also act as a Z-scheme “bridge” in keeping the strong reduction/oxidation ability of the electrons/holes for surface reactions. Furthermore, Pd nanocubes also increase the bonding strength between the two semiconductors. Enabled by this unique design, the hydrogen evolution achieved is dramatically higher than that of its counterpart C3N4-Cu2O structure without Pd embedding. The apparent quantum efficiency (AQE) is 0.9% at 420 nm for the designed C3N4-Pd-Cu2O. This work highlights the rational interfacial design of heterojunctions for enhanced photocatalytic performance.
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JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
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2017
·Vol. 29
·期 2
·1269-1279
·
IF 2.019
Hu Liang,Xia Yuting,Wang Qianqian,Yang Hui,Zhang Qi-long
In this work, a core–shell dendritic CuO@TiO 2 was constructed through a two-step chemical method. Structural analysis confirms the successful coating of TiO 2 on the CuO and the dendritic morphology was maintained after the coating process. The composites were prepared by using ferroelectric P(VDF-HFP) as matrix and synthesized particles as filler. The introduction of fillers influences the melting and crystallization process of the polymer matrix without altering the composition. The insulator layer suppresses the conductivity and dielectric loss by blocking the charge carriers while the composites exhibit improved dielectric constant in the frequency wide range of 10 2 –10 6 Hz and enhanced thermal conductivity. The composite with 20% CuO@TiO 2 exhibits a high dielectric constant of 51.7, low loss of 0.11 at 1 kHz and high thermal conductivity of 0.382 W/mK, showing huge potential for dielectric applications.
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CHEMICAL ENGINEERING JOURNAL
·
2017
·
IF 6.216
Jinhong Fan,Lin Gu,Deli Wu,Zhigang Liu
Among the numerous iron-based materials for persulfate (PS) activation, mackinawite (FeS) particles have gained considerable interest as a ubiquitous natural mineral due to their high reactivity. However, the iron and sulfur co-mediated reaction mechanism of PS activation by FeS remains ambiguous. In this study, FeS was applied as a catalyst to activate PS for p -chloroaniline (PCA) degradation and mineralization over a wide initial pH range (3.0–11.0). The reaction was found to follow pseudo-first-order kinetics, with rate constants ranging from 0.0044 to 0.0144 min −1 . The reaction mechanism was elucidated by electron spin resonance (ESR) and quenching studies. A heterogeneous activation mechanism, in which surface Fe(II) species activated PS to produce OH ads and SO 4 − ads , controlled by surface reaction and diffusion was proposed, whereas OH free and SO 4 − free diffusing from the FeS surface were mainly responsible for PCA degradation. The sulfur-mediated cycling of iron species was investigated by comparing PS activation by zero-valent iron (ZVI) and FeS, exogenous Fe(III) addition and X-ray photoelectron spectroscopy (XPS). The results suggested that Fe(II) and S(-II) experienced independent oxidations and that S(-II) species could regenerate Fe(II) from Fe(III) at the FeS surface. Therefore, the S(-II)-promoted Fe(II)/Fe(III) cycle resulted in less PS decomposition but a higher PCA mineralization efficiency. The findings of this study elucidated the novel surface activation mechanism of PS by FeS and provided useful information for utilizing FeS to remediate contaminated water.
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APPLIED CLAY SCIENCE
·
2016
·
IF 2.586
Zhujian Huang,Pingxiao Wu,Beini Gong,Xing Zhang,Zicong Liao,Pen-Chi Chiang,Xinjiang Hu,Lihua Cui
To further enhance the photocatalytic properties of doped-TiO 2 , a series of (N, Cu) co-doped TiO 2 /rectorite composites with different amount of N doping were prepared for adsorption and catalytic oxidation of p -chlorophenol ( p -CP) under visible light. The physicochemical properties of the obtained composites were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), etc. The results showed that the (N, Cu) co-doped TiO 2 catalyst was immobilized well onto rectorite , and the doping of N and Cu could affect the crystal structure of TiO 2 . The optimal N doping amount was determined by the photocatalytic degradation of p -CP in a stirred quartz reactor under visible light (> 420 nm) irradiation. It was found that the doping of N can improve significantly the degradation of p -CP and the optimum N doping amount is 1.0%. The adsorption of p -CP by the composites could accelerate the degradation rate of p -CP in situ. The photocatalytic activity of the (N, Cu) co-doped TiO 2 /rectorite composites remained stable after five cycles of photoreaction. A possible mechanism for the photocatalytic degradation of p -CP is proposed. Our work implied that rectorite has great potential to be applied in the field of photocatalysis .
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Catalysis Science & Technology
·
2014
·Vol. 5
·期 1
·405-414
·
IF 4.76
Hongmei Liu,Kai Tao,Chunrong Xiong,Shenghu Zhou
In this work, Pd–NiO@SiO2 core–shell mesoporous nanocatalysts with ~4 nm Pd–NiO heteroaggregate nanoparticle cores and ~17 nm mesoporous silica shells were successfully synthesized by a sol–gel method. The surfactant-capped PdNi alloy nanoparticles were coated with SiO2 through hydrolysis of tetraethylorthosilicate to obtain PdNi@SiO2 nanoparticles, and the mesoporous Pd–NiO@SiO2 core–shell nanocatalysts were formed after removal of surfactants by calcination at 500 °C and subsequent H2 reduction at 200 °C. The characterization results by XRD, TEM and BET revealed that Pd–NiO@SiO2 nanocatalysts were highly stable with the maintenance of intact core–shell structures under high-temperature thermal treatments. The Pd–NiO@SiO2 nanocatalysts illustrated a superior catalytic performance for p-chloronitrobenzene hydrogenation with H2 to the control Pd@SiO2 nanocatalysts. The catalytic performance enhancement of Pd–NiO@SiO2 nanocatalysts is ascribed to the strong interaction between Pd and NiO in the cores, where the interfaces may be beneficial for hydrogenation reactions.
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Nanoscale
·
2012
·Vol. 4
·期 24
·7817-7824
·
IF 5.914
Yang Wang,Shouchuan Li,Hui Shi,Ke Yu
Two kinds of Cu2O–ZnO nano-heteroarchitectures were fabricated through a hydrothermal method. By utilizing polyethyleneimine (PEI) as a binding agent, ZnO nanoparticles were uniformly self-assembled onto Cu2O micro structures. Photoluminescence (PL), field emission and photocatalytic activities of the composite samples were investigated and compared with those of the pure Cu2O samples. The results reveal that ZnO nanoparticles combined on Cu2O microstructures remarkably changed the PL signals, and significantly enhanced the field emission and photocatalytic activities. The novel PL properties, enhanced field emission and photocatalysis activities are attributed to the electron transition and the inhibition of photo-induced electron–hole pairs recombination, which stem from interfacial defect states and energy band differentials at the interface of Cu2O and ZnO. The surface nano-protrusions, large surface area and better dye adsorption induced by ZnO nanoparticles are responsible for the field emission and photocatalysis improvements as well.
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Science China-Materials
·
2015
·Vol. 58
·期 9
·693-703
·
IF 0
Liu Jian,Zhao Yuheng,Liu Jialong,Wang Shouguo,Cheng Yan,Ji Muwei,Zhou Yuanmin,Xu Meng,Hao Weichang,Zhang Jiatao
Heterovalent doping represents an effective method to control the optical and electronic properties of semiconductor nanocrystals (NCs), such as the luminescence and electronic impurities (p-, n-type doping). Considering the phase structure diversity, coordination varieties of Cu atoms in Cu 2 S NCs, and complexity of Cu doping in II-VI NCs, monodisperse Cu 2 S NCs with pure hexagonal phase were synthesized firstly. Then through cation exchange reaction between Cd ions and well-defined Cu 2 S NCs, dominant Cu(I) doped CdS NCs were produced successfully. The substitutional Cu(I) dopants with controllable concentrations were confirmed by local atom-specific fine structure from X-ray absorption near edge structure (XANES), extended X-ray absorption fine structure (EXAFS) spectroscopy, elemental analysis characterizations from X-ray photoelectron spectroscopy (XPS) and the electron spin resonance (ESR) measurement. The dominant and strong Cu(I) dopant fluorescence was verified by their absorption and photoluminescence (PL) spectra, and PL lifetime. Finally, the band positions and the p-type conductivities of the as-prepared Cu 2 S and Cu(I) doped CdS NCs were identified by ultraviolet photoelectron spectroscopy (UPS) measurements. The high monodispersity of NCs enables their strong film-scale self-assembly and will hasten their subsequent applications in devices.
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BIOPROCESS AND BIOSYSTEMS ENGINEERING
·
2014
·Vol. 37
·期 11
·2353-2359
·
IF 1.823
Ganasen Ponnarasy,Khan Maksudur Rahman,Kalam M. Abul,Mahmud Mohd Sabri
This paper demonstrates Pseudomonas cepacia lipase catalyzed hydrolysis of p -nitrophenyl palmitate under irradiation of light with wavelengths of 250–750 nm. The reaction follows Michaelis–Menten Kinetics and the light irradiation increases the overall rate of hydrolysis. Using Lineweaver–Burk plot K
M and V
max values for the reaction in presence of light are found to be 39.07 and 66.67 mM/min/g, respectively; while for the same reaction under dark condition, the values are 7.08 and 10.21 mM/min/g. The linear form of enzyme dependent rate of reaction confirms that no mass-transfer limitations are present and the reaction is a kinetically controlled enzymatic reaction.
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CATALYSIS LETTERS
·
2015
·Vol. 145
·期 3
·784-793
·
IF 2.307
Zhang Xuejun,Zhang Peipei,Yu Hongbo,Ma Zhen,Zhou Shenghu
Abstract Bimetallic PdM (M = Ni, Co, Fe) nanoparticles were synthesized using butyllithium as a reductant, and were used to prepare Pd–M
x
O
y
/KIT-6 catalysts by appropriate oxidation and reduction treatments. These catalysts showed higher selectivity in the hydrogenation of p -chloronitrobenzene to p -chloroaniline than Pd/KIT-6. Relevant characterization was conducted using X-ray diffraction, transmission electron microscopy, N 2 adsorption–desorption, X-ray photoelectron spectroscopy, inductive coupled plasma emission spectrometer, and H 2 temperature-programmed reduction. Graphical Abstract
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Molecular Catalysis
·
2024
·
IF 3.9
Yang Chen,Yatao Yan,Mengting Shao,Yongjian Xu,Guowang Diao,Ming Chen
In this work, N, P-Co 4 S 3 /NC nanospheres were successfully synthesized by double ligand strategy, followed by calcination and phosphating. By adjusting the radio of methimazole and 2-methylimidazole, and changing the calcination temperature, we obtained the optimal hydrogen evolution catalyst. The doping of N and P can regulate the electronic structure of Co, and further improve the electrocatalytic hydrogen production performance. Furthermore, N from dual ligands can form nitrogen-doped carbon, thus enhancing the conductivity and stability of the catalyst. The experimental results showed that N, P-Co 4 S 3 /NC exhibited good full pH activity in 0.5 M H 2 SO 4 , 1.0 M PBS and 1.0 M KOH, and the overpotentials of 163, 185 and 168 mV were required to reach the current density of 10 mA cm −2 , respectively. In this study, the dual ligands strategy can propose a new path for the design and synthesis of the catalyst precursor, and N, P codoping can effectively enhance the catalyst performance.
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