JOURNAL OF MATERIALS SCIENCE
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2020
·Vol. 55
·期 26
·11970-11983
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IF 3.553
Niu Yingchun,Li Xueai,Dong Wenqi,Zhang Can,Zhao Kuihu,Wang Fengyan,Wang Haiyan
Carbon and iron composites have drawn much attention for their unique electromagnetic properties. In addition, nitrogen doping of carbon can effectively modulate the dielectric properties of carbon. Therefore, synthesis of N-doped carbon and iron composites is an alternative method for obtaining high-efficiency microwave absorption materials. In previous studies, the synthesis process was very complicated including multistep routes. In this work, N-doped carbon with embedded Fe/Fe 3 C was synthesized in-situ via pyrolysis of amino phenol formaldehyde resin (APF) scattered with Fe 2 O 3 nanoparticles (APF/Fe 2 O 3 ), which was obtained through a simple hydrothermal process. During the heat-treatment process, the APF resin was converted into N-doped carbon, and simultaneously, the Fe 2 O 3 was reduced to iron nanoparticles. Then, inevitably, the iron nanoparticles reacted with carbon to form Fe 3 C at the interface between the iron particles and carbon. Taking advantage of multiple heterogenous interface, the interfacial polarization relaxation could be enhanced. Therefore, the N-doped carbon with embedded Fe/Fe 3 C particles displays microwave absorption with a maximum reflection loss of − 70 dB. Moreover, the effective absorption bandwidth (reflection loss of less than − 10 dB) reaches 6.02 GHz at a thickness of 2.13 mm. This study not only provides composites of N-doped carbon with embedded Fe/Fe 3 C particles with excellent stable microwave absorption but also offers a simple method for synthesizing N-doped carbon with embedded Fe/Fe 3 C particles.
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高影响因子
SENSORS AND ACTUATORS B-CHEMICAL
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2020
·
IF 7.1
Li Lv,Pengfei Cheng,Yinglin Wang,Luping Xu,Bao Zhang,Chao Lv,Jian Ma,Yue Zhang
In this paper, the preparation process and gas sensing performance of Sb-doped three-dimensional spinel ferrite (3D ZnFe 2 O 4 ) with well-assembled macroporous spherical structure have been investigated. Sb-doped 3D ZnFe 2 O 4 macroporous spheres (MPs) were prepared through a one-step ultrasonic spray pyrolysis (USP) method by sacrificing self-assembly sulfonated polystyrene spheres (S-PSs). The interconnected macropores (an average pore size about 200 nm) can be observed in the as-prepared materials by SEM and TEM characterization, which provided the dual functions of accelerating the diffusion of gas molecules and providing more reactive sites. The XPS analysis showed that the element Sb existed as Sb 5+ in doped samples. Compared with the pure 3D ZnFe 2 O 4 MPs (response = 18), 0.5 % Sb-doped sample presented the response of 35.5–100 ppm n-butanol at 250 °C, and also revealed excellent selectivity and long-term stability to n-butanol. The greatly enhanced sensing performance of Sb-doped simples can be attributed to the construction of 3D spheres with interconnected macroporous structures and the modification of Sb doping. The formation of p-n junctions at interface through Sb doping also improved the sensing performance for n-butanol. In addition, the relative sensing mechanism of Sb-doped 3D ZnFe 2 O 4 MPs for n-butanol sensing has been discussed in detail.
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高影响因子
MICROCHEMICAL JOURNAL
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2020
·
IF 3.594
Xuejian Xing,Li Huang,Shaojing Zhao,Jiafu Xiao,Minhuan Lan
S,N-doped carbon dots (S,N-CDs) were facilely prepared via a hydrothermal method by using thiourea and citric acid (CA) as precursors. The as-prepared S,N-CDs exhibited high stability in aqueous solution and were applied for fluorometric detection of tetracyclines (TCs). The approach was developed on the basic of the fluorescence of S,N-CDs at 440 nm, which was selectively quenched by TCs through the inner filter effect (IFE) mechanism. Moreover, the fluorescence of TCs with maximum at 600 nm could be used as the internal standard signal, resulting in a fluorometric spectral response. The limit of detection (LOD) was 0.25, 0.39 and 0.26 μM for tetracycline (TC), doxycycline (DC) and oxytetracycline (OTC), respectively. Furthermore, S,N-CDs were successfully utilized for the detection of residual TCs in fish and pork samples with acceptable recovery and good RSD.
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ACS Applied Nano Materials
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2020
·
IF 0
Hao Zhang,Xiaojing Song,Chen Zhao,Dianwen Hu,Wenxiang Zhang,Mingjun Jia
Designing highly efficient heterogeneous catalysts for the Friedel–Crafts acylation (FCA) reaction is a very significant subject for the development of green chemical industry. Herein, a series of nanosized iron carbide-encapsulated N-doped porous carbons (FexC/NC-n) have been prepared through high-temperature pyrolysis of the Fe-Zn bimetallic organic framework for the catalytic application in FCA of aromatic compounds with acyl chlorides. A variety of characterization results demonstrated that the nanosized iron carbides (FexC), which are wrapped inside of the graphitic carbon shell, are the main active sites for the FCA reaction. Changing the ratios of Fe/Zn can considerably influence the particle size of FexC and the thickness of the graphitic carbon shell. The composition-optimized catalyst, named as FexC/NC-0.05, exhibited the highest activity and excellent recyclability for the reaction. The relatively thin graphitic carbon shell allows rapid penetration of reagents and, meanwhile, can also provide effective protection for the active FexC particles against leaching by space confinement and electronic effects, thus resulting in the formation of highly active and stable FexC/NC-n catalysts for the FCA reaction.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2020
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IF 4.939
Chuan Long,Chuanrui Lu,Yunxi Li,Zhihua Wang,Hong Zhu
Graphene oxide (GO) is a potential material in the electrode and membrane of polymer electrolyte membrane fuel cells due to its unique structure and various oxygen-containing functional groups. A class of three-layered GO/poly (phenylene oxide) for AEMs was prepared in this work. GO was functionalized with highly stable 6-azonia-spiro [5.5]undecane groups and used as a fast hydroxide conductor, named ASU-GO. Functionalized by N-spirocyclic cations, poly (phenylene oxide) (PIPPO) was then combined with ASU-GO and GO to fabricate the ASU-GO/PIPPO and GO/PIPPO. Notably, the maximum hydroxide conductivity of the ASU-GO/PIPPO was 73.7 mS cm −1 at 80 °C, which was 3 times higher than that of the GO/PIPPO. The enhancement in hydroxide conductivity was due to the changes in the hydroxide transport mechanism and the poor stacked structure of the ASU-GO layer. Only 10.8% drops in hydroxide conductivity of ASU-GP/PIPPO after the alkaline test (1 M KOH at 80 °C for 700 h). Furthermore, the ASU-GO/PIPPO-50 membrane showed a maximum peak power density of 102 mW cm −2 , demonstrating the prepared membrane was promising in the AEM applications.
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PHYSICAL CHEMISTRY CHEMICAL PHYSICS
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2020
·Vol. 22
·期 14
·7218-7223
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IF 3.43
Mengyao Lv,Haichuan Guo,Hangjia Shen,Jun Wang,Jiacheng Wang,Yuichi Shimakawa,Minghui Yang
A key challenge in carrying out an efficient oxygen reduction reaction (ORR) is the design of a highly efficient electrocatalyst that must have fast kinetics, low cost and high stability for use in an energy-conversion device (e.g. metal–air batteries). Herein, we developed a platinum-free ORR electrocatalyst with a high surface area and pore volume via a molten salt method along with subsequent KOH activation. The activation treatment not only increases the surface area to 940.8 m2 g−1 by generating lots of pores, but also promotes the formation of uniform Fe3C nanoclusters within the atomic dispersed Fe–Nx carbon matrix in the final material (A-FeNC). A-FeNC displays excellent activity and long-term stability for the ORR in alkaline media, and shows a greater half-wave potential (0.85 V) and faster kinetics toward four-electron ORR as compared to those of 20 wt% Pt/C (0.83 V). As a cathode catalyst for the Zn–air battery, A-FeNC presents a peak power density of 102.2 mW cm−2, higher than that of the Pt/C constructed Zn–air battery (57.2 mW cm−2). The superior ORR catalytic performance of A-FeNC is ascribed to the increased exposure of active sites, active single-atom Fe–N–C centers, and enhancement by Fe3C nanoclusters.
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PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2020
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IF 10.652
Jianan Yu,Zhiliang Zhu,Hua Zhang,Xiaolin Shen,Yanling Qiu,Daqiang Yin,Shaobin Wang
Metal-free carbocatalysts are raising increased interest in advanced oxidation processes (AOPs) for green degradation of aqueous organic pollutants. In the present study, a series of N-doped hydrochars (NHCs) was prepared from pinewood biomass and used in carbocatalysis toward catalytic peroxymonosulfate (PMS) activation to degrade refractory endocrine disrupting compounds. Nitrogen-doping was found to regulate the concentrations and types of persistent free radicals (PFRs) on hydrochar, promoting the electron transfer and oxidative degradation of the contaminants. Mechanistic studies revealed that graphitic N not only shows a strong electron transfer to facilitate PMS activation in a nonradical pathway, but also induces the formation of oxygen-centered PFRs from the structure defects for a radical oxidation pathway. More importantly, the PMS/NHC system demonstrates efficient degradation and satisfactory stability for real water treatment. This study has gained in-depth understanding on the roles of N-dopants in radical and nonradical pathways of biomass-based carbocatalysis, and will provide a promising and environmental-friendly route for efficient degradation of refractory endocrine disrupting compounds for green remediation.
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ACS Applied Electronic Materials
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2021
·
IF 3.314
Jingyu Li,Changshuai Dong,Junli Hu,Jun Liu,Yichun Liu
The intrinsic flexibility makes conjugated polymers an ideal choice for wearable thermoelectrics. The n-type polymer thermoelectric is still in its infancy. The majority of research on the n-type polymer thermoelectric focuses on the design of n-type conjugated polymers and high-efficiency n-dopants. In this paper, we report a self-standing and flexible nanofiber mat of an n-type conjugate polymer prepared with electrospinning technology. We choose a representative n-type conjugate polymer N2200. The electrospun N2200 nanofiber mat shows a maximal conductivity of 7.06 × 10–4 S/cm, a maximal Seebeck coefficient of −346 μV/K, and a maximal power factor of 0.0085 μW/(m K2). This thermoelectric performance is fairly comparable to that of the traditional spin-coated N2200 thin film. The nanofiber mat is self-standing, flexible, and stretchable and thus can attach to human skin and move with body movement. This work demonstrates the feasibility of fabricating flexible thermoelectric devices by an electrospinning technique and lays a foundation for the applications of n-type conjugated polymers in wearable electronics.
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JOURNAL OF POWER SOURCES
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2021
·
IF 9.127
Ailing Tian,Kailin Luo,Zhendong Li,Mingming Ma,Shun Li,Xingyi Wang,Deyu Wang,Zhe Peng
Lithium (Li) metal and alloy anodes are strongly attractive for next high-energy-density batteries , owing to their high theoretical specific capacity and low redox potentials . However, the fast electrode pulverization caused by large volume variation upon cycling inhibits the use of the Li metal and alloy anodes seriously, whereas the sluggish charge transfer and weak electrode/electrolyte interphase are mainly responsible for their uneven volume expansion and surface breaks, respectively. Herein, a versatile F–N–S doped lithiophilic interphase is obtained via a one-pot electrochemical fabrication process with high controllability, which exhibits high robustness, Li affinity and fast Li transfer, and significantly outperforms the single lithiophilic interphase obtained via chemical route. When this advanced interphase is applied to the copper or aluminum electrodes, great stabilizations of Li plating/stripping or Li insertion/extraction processes can be achieved. This work emphasizes the importance of the interphase composition for designing stable high-energy-density electrodes, and gives insights on a general and efficient remedy to boost the performances of the large-volume-change electrodes.
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THERMOCHIMICA ACTA
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2021
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IF 3.115
Lei Liu,Xiang Cheng,Xiwang Miao,Ying Zhang,Min Guo,Fangqin Cheng,Mei Zhang
In this work, a series of SiO 2 @n-octadecane capsules were prepared by one step emulsion polymerization, the influence of emulsifying speed, ammonia and TEOS contents, reaction temperature, concentration of emulsifier and the amount of PVP on the size, structure and performance was detailed investigated. It can be seen from SEM characterization that among these factors emulsification speed had the greatest influence on capsule size, while followed by the ammonia and TEOS content. According to TEM results, the ammonia and TEOS contents were the most important factors on the structure (shell thickness and surface smoothness) of the capsules, attributing to ammonia and TEOS were the catalyst and reactant of hydrolysis polymerization, respectively. Generally, the crystallinity of the samples became worse as the size decreased. DSC results showed that excessive ammonia or TEOS caused a significant drop in the enthalpy of the samples, furthermore, the enthalpy basically decreased with the attenuation of the inner radius of the sample. The target SiO 2 @n-octadecane capsule was sample C2 with high enthalpy (127.7 J/g), size of 1.62 μm, shell thickness of 68 nm, and smooth surface. More importantly, within the parameters studied, a series of SiO 2 @n-octadecane capsules were successfully synthesized with different enthalpy values (min 85.9 J/g, max 144.3 J/g), sizes ranging from 0.63–2.75 μm, shell thickness 32–79 nm and different smooth surfaces. Therefore, the controllable synthesis of SiO 2 @n-octadecane capsules within the above range can be achieved by simulating different parameters and their development.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2021
·
IF 5.816
Yuqing Chi,Shuyi Zheng,Xiangwen Zhang,Guozhu Li
Selective hydrogenation of nitroarene to aniline is a key reaction for the manufacture of fine chemicals, pharmaceuticals, and dyes. In this study, N-doped carbon nanotubes (NCNTs) are prepared by the pyrolysis of chitosan-CNTs composite. The outside diameter of CNTs, concentration of chitosan, pyrolysis temperature and heating rate are tuned to improve the catalytic performance. The catalyst of CS/CNTs-800 doped with 0.33% pyrrolic N and 0.30% graphitic N exhibits good activity and high selectivity for the hydrogenation of nitroarenes. The kinetics data reveal that the hydrogenation reaction is zero-order for 4-nitrophenol and first-order dependence to H 2 pressure, and H 2 dissociation on the active sites is the rate-determining step. On CS/CNTs-800, the nitro groups of 12 different substrates can be selectively reduced with the protection of the other reducible groups. Nonpolar H radicals are found to be formed on CS/CNTs-800 for efficient hydrogenation. In addition, the catalyst showed good stability.
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高影响因子
CELLULOSE
·
2021
·Vol. 28
·期 13
·8855-8866
·
IF 5.044
Peng Panpan,Zhang Ziwen,Yang Jianjun,Wu Mingyuan,Wu Qingyun,Liu Jiuyi,Zhang Jianan
Abstract An N -halamine precursor 2-(3-(6-methyl-4-oxo-1,4-dihydropyrimidin-2-yl)ureido)ethyl methacrylate (SCMHBMA) was synthesized and grafted on cotton fabrics via atom transfer radical polymerization for antibacterial function after chlorination. The preparation and chlorinated cotton fabrics (Cotton-g-PSMA-Cl) were characterized with FTIR, XPS, SEM, and TGA. The properties of prepared Cotton-g-PSMA-Cl, including thermal property, antibacterial efficiency, durability, and stability, were systematically evaluated. The results showed that these chlorinated Cotton-g-PSMA-Cl fabrics possessed excellent antibacterial activity against E. coli. and S. aureus . After 10 washing cycles and 60 days of routine storage, active chlorine concentrations (Cl + %) were reduced only 22% and 18%, respectively, and the reduced Cl + % effectively reverted by simple rechlorination. This new N -halamine antibacterial cotton composite with superior antibacterial properties exhibited potential for future application in the long-term antibacterial field. Graphic abstract
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高影响因子
危险品化学品经营许可证（带存储）