GREEN CHEMISTRY
·
2019
·Vol. 21
·期 8
·2129-2137
·
IF 9.405
Di Liu,Ping Yang,Hao Zhang,Minjie Liu,Wenfei Zhang,Dongmei Xu,Jun Gao
A non-noble heterogeneous catalyst – a Co, N and C composite encapsulated carbon nanotube grown in situ on the surface of activated carbon (Co–N–C/CNT@AC) – was fabricated via the pyrolysis–reduction process. Co–N–C/CNT@AC catalyzed the reductive coupling of structurally diverse nitroarenes and alcohols to imines and secondary amines under exogenous base- and solvent-free conditions. BET, TEM, SEM, XRD and XPS characterization showed that the exceptional catalytic property of Co–N–C/CNT@AC could be explained by its nanostructure, Co–N and basic N species. Our protocol had advantages of low cost, environment-friendliness, and good applicability. Furthermore, a reaction route of nitroarenes, amines and alcohols as the starting materials was proposed to improve the atom economy of the reductive coupling of nitroarenes with alcohols.
研究领域:
化学
·
环境科学
·
材料科学
✓ 已验证
DOI
高影响因子
Nanomaterials
·
2025
·Vol. 15
·期 11
·806
·
IF 4.3
Xiaojiao Yang,Shuai Han,Hongna Xing,Yi Dong,Xia Deng,Yan Zong,Juan Feng,Xiuhong Zhu,Xinghua Li,Xinliang Zheng
MOFs-derived magnetic carbon-based composites are considered to be valuable materials for the design of high-performance microwave absorbents. Regulating phase structures and introducing mixed-valence states within the composites is a promising strategy to enhance their charge transfer properties, resulting in improved microwave absorption performance. In this study, iron oxide components show a temperature-dependent phase evolution process (α-Fe 2 O 3 →Fe 3 O 4 →Fe 3 O 4 /FeO), during which the valence states of iron ions are regulated. The tunable phases modulate the magnetic Fe 3 O 4 component, resulting in enhanced magnetic loss. The changed valence states affect the polarization relaxation by adjusting the electronic structure and tune the electron scattering by introducing defects, leading to enhanced dielectric loss. The microwave absorption properties of iron oxide@carbon composites display phase- and valence state-dependent characteristics. Especially, Fe 3 O 4 @C composites exhibit superior microwave absorption properties, ascribed to the improved magnetic/dielectric losses induced by good impedance matching and strong microwave attenuation capacity. The minimum reflection loss of Fe 3 O 4 @C composites reaches −73.14 dB at 10.35 GHz with an effective absorption bandwidth of 4.9 GHz (7.69–12.59 GHz) when the absorber thickness is 2.31 mm. This work provides new insights into the adjustment of electromagnetic parameters and microwave absorption properties by regulating the phase and valence state.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF POWER SOURCES
·
2015
·
IF 6.217
Zhian Zhang,Xing Yang,Zaiping Guo,Yaohui Qu,Jie Li,Yanqing Lai
Selenium/carbon-rich (Se/carbon-rich) core–shell composites are prepared by a one-step hydrothermal synthesis method as a cathode for rechargeable lithium batteries . The Se/carbon-rich composites are characterized and examined by X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetry (TGA) measurements. It is demonstrated from galvanostatic discharge/charge process that the Se/carbon-rich composites exhibit the discharge capacity of 558 mA h g −1 in the first cycle and maintain capacity of 181 mA h g −1 after 80 cycles at a rate of 0.5C, which is better than that of the pristine selenium. The result demonstrates that the unique core–shell structure is effective in suppressing the dissolution of polyselenides into the electrolyte and in maintaining high utilization of the active materials during the charge/discharge process. It provides a new selenium-based cathode material for rechargeable lithium batteries .
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
·
2023
·
IF 10.9
Yuxiao Jia,Xuancheng Wang,Leijie Hu,Xuezhang Xiao,Shuoqing Zhang,Jiahuan He,Jiacheng Qi,Ling Lv,Fen Xu,Lixian Sun,Lixin Chen
Ultrafine carbon-based transition metal compounds have been widely investigated as efficient catalysts for enhancing the hydrogen storage performance of magnesium hydride. In this work, the carbon thermal shock method is applied to synthesize the ultrafine carbon-encapsulated NbC nanoparticles with an average grain size of 17.3 nm. The MgH 2 –10 wt% NbC/C composites show excellent low-temperature hydrogen storage performance with the onset dehydrogenation temperature of 196.1 °C, which is 92.2 °C and 98 °C lower than that of MgH 2 –10 wt% NbC and undoped MgH 2 , respectively. Specifically, MgH 2 –10 wt% NbC/C can absorb 6.71 wt% H 2 at 100 °C within 30 min around and retain almost 100% reversible hydrogen desorption capacity after 10 cycles. For the catalytic mechanism, the electron transfer process between multi-valence Nb cations of in-situ formed NbH x and Mg, H atoms can greatly improve the cyclic de/rehydrogenation kinetics of MgH 2 -NbC/C. Besides, the enhancement of dehydrogenation kinetics can also be ascribed to MgH 2 particle refinement by NbC nanoparticles, and destabilization of the Mg-H bond caused by carbon substrate. This investigation not only proves that carbon-encapsulated NbC nanoparticles can greatly enhance the hydrogen storage performance of MgH 2 but provides an idea of preparing carbon-based transition metal carbides as effective catalysts for magnesium-based hydrogen storage materials.
研究领域:
材料科学
·
能源存储
✓ 已验证
DOI
高影响因子
NANOTECHNOLOGY
·
2020
·Vol. 31
·期 39
·395710
·
IF 3.551
Yan Wang,Xiaochuang Di,Xiang Gao,Xinming Wu
Carbon-based composites have triggered tremendous attention in the development of high-efficiency microwave absorbers, due to their compatibility, light weight, and high microwave absorption. However, fabricating carbon-based absorbers with a strong absorption ability in a broad frequency range is challenging. Hence, a facile strategy was used to produce Co@C derived from a zeolitic imidazolate framework (ZIF)@ graphene. The Co@C@RGO composite was obtained by annealing the ZIF67/GO nanocomposite precursor at 650 °C in a nitrogen atmosphere. Due to the magnetic loss induced by the Co particles, the dielectric loss generated by the carbon skeletons and graphene, and the interfacial polarization between the components, the hierarchical composite exhibits superior electromagnetic (EM) wave absorption properties. The optimal reflection loss (RL) of the Co@C@ RGO composite can be up to −67.5 dB at 2.6 mm, and the effective bandwidth (≥−10 dB) is 5.4 GHz (10–15.4 GHz) with a thickness of 2 mm at 20 wt% loading. The dipolar polarization caused by graphene, as well as enhanced impedance matching, synergistic effect and interfacial effect among the components, increase the microwave absorption performance of the composite. This work may open a new path to use the Co@C@RGO composite with its high-efficiency EM wave properties as an absorber.
研究领域:
材料科学
·
电磁学
✓ 已验证
DOI
高影响因子
Frontiers of Chemical Science and Engineering
·
2021
·Vol. 15
·期 5
·1125-1133
·
IF 4.204
Cui Yan,Zeng Zequan,Zheng Jianfeng,Huang Zhanggen,Yang Jieyang
To realize the utilization of visible light and improve the photocatalytic efficiency of organic pollutant degradation in wastewater, a nitrogen-doped titanium-carbon composite (N-TiO 2 /AC) prepared by sol-gel methods was applied in the photodegradation of phenol assisted by persulfate under visible light irradiation (named N-TiO 2 /AC/PS/VIS). The results show that a synergistic effect exists between visible-light photocatalysis and persulfate activation. Compared with TiO 2 /PS/VIS, the phenol degradation rate was found to be observably improved by 65% in the N-TiO 2 /AC/PS/VIS system. This significant increase in degradation rate was mainly attributed to the following two factors: 1) The N and C doping can change the crystal structure of TiO 2 , which extends the TiO 2 absorption wavelength range to the visible light region. 2) As an electron acceptor, PS can not only prevent electrons and holes from recombining with each other but can also generate strong oxidizing radicals such as ·SO 4 − and ·OH to accelerate the reaction dynamics. The process of phenol degradation was found to be consistent with the Langmuir pseudo-first-order kinetic model with an apparent rate constant k of 1.73 min −1 . The N-TiO 2 /AC/PS/VIS process was proven to be a facile method for pollutant degradation with high pH adaptability, excellent visible-light utilization and good application prospects.
研究领域:
环境科学
·
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
Sustainable Energy & Fuels
·
2020
·Vol. 4
·期 5
·2583-2592
·
IF 5.503
Yong Wang,Xiaolan Wang,Hong Jin,Yu Bai,Hui Xu
Using silicon/carbon composites is one of the most attractive strategies to improve the anode performance for lithium ion batteries. Nevertheless, the adhesion between silicon and carbon can be hardly maintained. It is critical to enhance the silicon/carbon structure stability. Here, we report a facile procedure to design a stable Si@CA@RH anode. Silicon nanoparticles are encapsulated with citric acid that can buffer the volume change and maintain the connection with the carbon structure via ester bonds. A rice husk derived carbon skeleton is used to facilitate the electronic conductivity network as well as the structural stability of the electrode. The hierarchically porous carbon matrix provides sufficient space to accommodate the volume expansion of Si and shortens the lithium-ion transportation distance. Hence, the Si@CA@RH electrode exhibits a stable capacity of 2126 mA h g−1 and high coulombic efficiency of 99.5% after 250 cycles. This strategy gives a perspective on alternative design of integrated carbon/silicon anode materials for high-performance Li-ion batteries.
研究领域:
材料科学
·
能源存储技术
✓ 已验证
DOI
高影响因子
ACS Applied Energy Materials
·
2022
·
IF 6.959
Ziyu Zhang,Chang Liu,Yunkun Dai,Bo Liu,Pan Guo,Fengdi Tu,Miao Ma,Lixiao Shen,Zigang Zhao,Yangyang Liu,Yunlong Zhang,Lei Zhao,Zhenbo Wang
Carbon supports for cathodic catalysts in proton-exchange membrane fuel cells suffer from rapid corrosion and instability; therefore, alternative supports with a stable structure and a high electric conductivity are highly required. In this paper, a three-dimensional support hybridized by MXene and Ketjen Black is developed, in which Ketjen Black is sandwiched between MXene nanosheets (MCM). After decorating with Pt nanoparticles by a facile wet-chemical approach, a three-dimensional (3D) Pt/MCM catalyst is obtained. The intercalated Ketjen Black prevents the stacking of MXene nanosheets, thus increasing the specific surface area of the catalyst and exposing the active sites. The strong interaction between functionalized MXene nanosheets and Pt nanoparticles further enhances its intrinsic electrocatalytic activity. Pt/MCM demonstrated encouraging ORR activity with the half-wave potential and specific activity of 0.892 V and 0.377 mA·cm–2, respectively, surpassing the state-of-the-art Pt/C catalysts. Especially, Pt/MCM achieves ultrahigh durability with a 1 mV decrease in half-wave potential and a 1.73% decrease in mass activity after an accelerated durability test. Given the performance and structure–activity relationships of Pt/MCM, it holds great potential for various energy and catalysis-related applications.
研究领域:
材料科学
·
电化学
·
能源技术
✓ 已验证
DOI
高影响因子
Journal of Energy Storage
·
2025
·
IF 9.8
Enxuan Li,Liangyu Liu,Leiyun Han,Chunli Guo,Peng Liu,Xiaoyang Liu
NiMoO 4 (NMO) and NiMoO 4 ·xH 2 O/carbon composites with rod-like structures were prepared by a simple, fast, and environmentally friendly microwave-assisted method and the effects of different carbon sources on their electrochemical properties were investigated. Glucose and potato starch were used as carbon sources, respectively, and the prepared materials, named NMOG and NMOS, were characterized by powder X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. Their electrochemical behaviors were examined by cyclic voltammetry (CV) and constant-current charge-discharge (GCD) techniques. The NiMoO 4 ·xH 2 O/carbon composites exhibited higher specific capacitance than NiMoO 4 due to its low crystallinity and good electrical conductivity of carbon. The specific capacitances were measured at 318.5, 420.5, and 485.3 F g −1 respectively at a current density of 1 A g −1 . In addition, asymmetric supercapacitors (ASCs) were constructed using prepared NMOS-2 as the positive electrode and activated carbon (AC) as the negative electrode. The energy density was 21.62 Wh kg −1 at a power density of 800 W kg −1 . The NMOS-2//AC ASC device showed good cycling stability with 85 % capacity retention after 10,000 cycles. This indicates that NMOS-2 is a promising electrode material for supercapacitors.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
Journal of Nano Research
·
2015
·
IF 0.564
Lin Qi,Li Xin Song,Xin Fei Zhao,Chang Jiang Fang,Xing Ran Lin,Jie Xiong
Flexible alumina (Al2O3)/carbon (C) composite nanofibers film has been fabricated via electrospinning, followed by pre-oxidation and carbonization. Polyacrylonitrile (PAN)/Polyvinylpyrrolidone (PVP) and aluminum hydroxyacetate (Al(OH)C4H6O4) acted as carbon precursor and Al2O3 precursor, respectively. The obtained Al2O3/C nanofibers films were systematically characterized by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectra (FTIR), energy dispersive spectrometer (EDS), X-ray diffractometer (XRD) and flexural tests. The results indicated that Al2O3/C composite nanofibers with rough surface consisted of graphitic phase and γ-Al2O3 phase. The Al2O3 covering on the surface of nanofibers improved the flexibility of carbon nanofibers (CNFs) film. Moreover, with the amount of Al2O3 increasing, both flexural rigidity and flexural modulus of Al2O3/C nanofibers film decreased drastically. In the other words, the flexibility of CNFs film improved greatly. The Al2O3/C nanofibers film with the mass ratio of Al(OH)C4H6O4: PAN being 4:1 exhibited flexural modulus that was about 11 times lower than that of CNFs film without Al2O3, suggesting that the highly flexible Al2O3/C nanofibers film was obtained.
研究领域:
材料科学
·
纳米技术
·
生物医学工程
✓ 已验证
DOI
高影响因子
Journal of Energy Storage
·
2024
·
IF 8.9
Ziqi Liu,Ruolin Zhao,Feifan Hong,Sizhi Ding,Jiakun Yang,Renhuan Li,Yi Fan,Haizhen Liu,Jin Guo,Zhiqiang Lan
Hydrogen storage materials are the primary solution for addressing safety concerns in hydrogen energy storage and transportation. Despite the advantages of magnesium-based hydrogen storage materials, such as high capacity and good reversibility, their poor kinetic performances severely limit their practical applications. In this study, the synthesis of titanium nitride supported on carbon (TiN@C) was achieved through a controllable hydrothermal method , aiming to enhance the hydrogen storage performances of MgH 2 .With the catalytic action of TiN@C, MgH 2 could rapidly release over 6.0 wt% of hydrogen at 300 °C within 15 min, while the onset dehydrogenation temperature decreased to 226 °C. The dehydrogenated MgH 2 could reabsorb 5.80 wt% of hydrogen at 200 °C for 15 min with a reduced activation energy of 44.9 kJ·mol −1 , demonstrating excellent kinetic performance. Mechanism analysis revealed that the multiphase interface between MgH 2 (Mg) and TiN@C significantly improved the hydrogen desorption kinetics of materials, especially TiN and the in-situ formed TiH 2 were the main reasons for improving the hydrogen storage performance of materials.
研究领域:
材料科学
·
能源存储与转换
✓ 已验证
DOI
高影响因子
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2023
·Vol. 25
·期 12
·8564-8573
·
IF 3.3
Xiaoying Jiang,Yan Zhang,Feiyang Zhang,Jiashuo Tian,Liuping Zhang,Xinrui Zhao,Fengling Cui
Defect engineering has become a significant research area in recent years; however, little has been reported on the biological method for modulating the intrinsic carbon defects of the biochar framework. Herein, a fungi-enabled method for the fabrication of porous carbon/Fe3O4/Ag (PC/Fe3O4/Ag) composites was developed, and the mechanism underlying the hierarchical structure is elucidated for the first time. By regulating the cultivation process of fungi on water hyacinth biomass, a well-developed interconnected structure and carbon defects acting as potential catalytic active sites were formed. This new material with antibacterial, adsorption and photodegradation properties could be an excellent choice for treating the mixed dyestuff effluents with oils and bacteria, also guiding pore channel regulation and defect engineering in materials science. Numerical simulations were carried out to demonstrate the remarkable catalytic activity.
研究领域:
材料科学
·
环境生物学
·
微生物学
✓ 已验证
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）