CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Yang Guo,Haipeng Lu,Xian jian
Synthesizing lightweight, thin–profile, and high–performance microwave absorbers has emerged as an urgent research topic. A promising strategy for carbon–based materials to achieve these attributes is to rationally construct heterostructures. Herein, 0.89–1.54 at.% nitrogen(N)–doped carbon onion nanotube chains (NCONCs) were produced by blending CONCs harvested from candle combustion with HH 4 Cl and subjecting them to heating at 300–400 °C for 3 h. The hinge–like NCONCs revealed numerous electron transport paths, facilitating the formation of multi–tiered conduction networks. The N–doping introduced C–N groups and interfaces into the CONCs, which yielded extensive dipole and interfacial polarization. Simultaneously, the 1.14 at.% N–doping endowed NCONC–400 with suitable conductivity, thereby ensuring excellent impedance matching. The resulting synergistic effect of impedance matching and electromagnetic wave attenuation was clearly observed. Specifically, NCONC–400 exhibited exceptional performance with a maximum effective absorption bandwidth of 4.71 GHz and a peak reflection loss of –35.47 dB at 1.4 mm. The radar cross–section reduction demonstrated by NCONC–400 composites reached 21.43 dB cm 2 . These impressive results prove the distinctive advantages of CONCs in tailoring performance and optimizing impedance matching, which are appealing for lightweight and efficient microwave absorbers.
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PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2023
·Vol. 26
·期 4
·3263-3273
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IF 3.3
Ziwei Zhai,Bofeng Zhang,Yutong Wang,Guozhu Liu
Based on the disturbance of electronic density, nitrogen-doped nanocarbons show promising properties to anchor metal clusters. However, precisely regulating the coordination mode between N species and the active site remains challenging. Herein, we rationally designed three N types (graphitic N, pyridinic N and pyrrolic N) in nanocarbons to anchor Pt clusters for the benchmark propane dehydrogenation. The specific activity of the pyridinic-N-doped catalyst was 147.54 molC3H6 molPt−1 h−1 at 550 °C, which was 1.3 times higher than those of graphitic- and pyrrolic-N-doped catalysts. Unlike the regular tetrahedron Pt cluster in the graphitic-N catalyst or the distorted three-layered Pt cluster in the pyrrolic-N catalyst, the Pt cluster in the pyridinic-N catalyst was an inverted tetrahedron, which increased the contact degree without geometric repulsion towards C–H bond scission. The geometric parameters of detached H and C atoms in the methylene group for the pyridinic N catalyst was decreased to strengthen the C–H bond scission. After CH3CHCH3* adsorption, the Bader charge of the Pt active site also became highly positive, which tailored the d-band center closer to the Fermi level and provided more vacant orbitals for C–H bond breakage. Therefore, pyridinic N in nanocarbons is promising to anchor small-sized Pt for alkane dehydrogenation in terms of geometric and electronic effects.
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Forests
·
2023
·Vol. 14
·期 5
·965
·
IF 2.9
Gaojun Chen,Yudong Li,Enshan Han,Ziqiang Zhang,Xiaohui Yang,Desheng Zhou,Yanzhen He
The optimization of supercapacitive properties in carbon materials derived from cheap and sustainable wood scraps exhibits great application potential. Herein, in support of interfacial groups, polyaniline nanospheres were in situ constructed in the internal pore structure of wood scraps; further, the B and N elements were imported by carbonized and hydrothermal methods. The doped B regulated the species of N doping to improve the electrical conductivity of carbonized wood scraps, and it endowed a certain pseudo-capacitance. Coupled with the fine double-layer capacitance from the hierarchical structures constructed by carbonized nanospheres and wood scrap channels, a high specific capacitance of 406 F g−1at 0.5 A g−1, high energy density (17.71 Wh kg−1at 250 W kg−1) and cycle stability (93.04% capacitance retention after 10,000 cycles) were performed simultaneously. This study provided a new strategy to improve the supercapacitive performance of bio-carbon materials in terms of structure and conductance.Keywords:wood scrap;B/N co-doping;porous carbon;in situ synthesis;supercapacitor
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APPLIED PHYSICS LETTERS
·
2023
·Vol. 122
·期 18
·
IF 4
Xu Baoyin,Du Haozhe,Yang Bin,Ding Zhanhui,Wang Xiancheng,Wang Yanchao,Li Ziheng,Li Yongfeng,Yao Bin,Ma Hong-An,Lan Yucheng
The exploration of novel ultrawide bandgap (UWBG) semiconductors is becoming a challenging and compelling research focus on semiconductor physics, materials, and device applications. Ternary B–C–N compounds have attracted much attention because their electronic structure and semiconductor properties are quite different depending on the chemical composition and atomic arrangement of boron, carbon, and nitrogen elements in the lattice. However, the lack of well-controlled high-quality B–C–N crystals has limited their potential as UWBG devices. In this study, B–C–N compounds are synthesized in bulks from graphite and hexagonal boron nitride ( h -BN) using ball milling and high-pressure high temperature technique. The synthesized B–C–N compounds produced are highly crystallized layered-materials with intercalated graphene layers in C-doped h -BN layers. The doped carbon atoms occupy boron sites and nitrogen sites of the h -BN layers unbalanced, giving rise to the n -type conductivity of the B-C-N layered compounds. The measured optical bandgaps range from 3.4 to 6.0 eV, which can be regulated by the carbon content. Their electronic properties are also tunable. Our work is expected to initiate potential applications of the B–C–N material as UWBG semiconductors.
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Journal of the Australian Ceramic Society
·
2023
·Vol. 59
·期 5
·1231-1239
·
IF 1.9
Zhang Mengwen,Jiang Binyang,Yang Lutong,Cao Na,Li Zhaosheng,Fan Lei,Yang Shoulei
The emerging oscillatory pressure sintering technology is used to prepare high-performance Al 2 O 3 -Ti(C,N) ceramic tools for high-speed cutting. By recording the displacement during sintering, the sintering shrinkage rate of the Al 2 O 3 -Ti(C,N) composite was calculated, and the stress exponent n and sintering activation energy Q were calculated according to creep theory to determine the densification mechanism. In addition, the evolution of phases, microstructure and hardness of the composite was also observed. Results show that during oscillatory pressure sintering process at 1400 °C and 1300 °C, the stress exponent of Al 2 O 3 -Ti(C,N) composite is around 2.2 and the sintering activation energy is 486 kJ mol −1 , indicating that the densification mechanism is a diffusion-controlled grain boundary sliding of Al 2 O 3 phase. Additionally, as the oscillatory pressure increases, the average grain size of the Al 2 O 3 decreases and the Vickers hardness increases. Hardness achieves the highest 22.7 GPa when the median oscillatory pressure is 70 MPa at 1400 °C, which is 1 GPa higher than that of static pressure of 70 MPa.
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RARE METALS
·
2023
·Vol. 42
·期 7
·2284-2293
·
IF 8.8
Du Juan,Lin Qin-Yan,Zhang Jian-Qi,Hou Sen-Lin,Chen Ai-Bing
Herein, we successfully prepare highly dispersed and uniform small nano-size nickel nanoparticles embedded on core–shell carbon spheres by confined-deposition method. The mesoporous silica layer containing surfactant coated on the surface of the polymer sphere provides confined space and effectively controls the growth of nickel nanoparticles during pyrolysis. At the same time, the introduction of nickel species has an impact on structure of the obtained carbon spheres, and it can promote the deposition of carbon to realize the adjustment from hollow to core–shell and then to solid spheres. Owing to the uniform distribution of Ni nanoparticles with small size, mesoporous structure, N-doping groups, high specified surface areas, and core–shell structure, the obtained catalyst shows exciting ability for the production of CO by reduction of CO 2 with a maximum CO Faradaic efficiency of 98%, indicating its promising prospect in electro-reduction of CO 2 . Graphical Abstract
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JOURNAL OF POWER SOURCES
·
2023
·
IF 9.2
Longhua Sun,Xiaodong Meng,Jie Zhang,Yongqiang Meng,Manyun Wang,Xueqin Zhou,Chao Chen,Ji Zhou,Christopher W. Bielawski,Jianxin Geng
The hybridization of carbon materials with metal compounds is a promising approach for designing advanced composites. However, the standard methodologies are often limited in practical terms by the complicated synthetic routes and/or an inability to control the structures of the resulting materials. Herein, we describe a one-pot strategy for synthesizing a N-doped porous graphitic carbon that is hybridized with oxygen-doped titanium nitride (designated O–TiN@N-PGC) and show that the composite displays outstanding chemisorption and electrocatalytic effects in sulfur cathodes. The method employs urea as nitrogen source and thus avoids the use of dangerous and toxic ammonia gas. The unique structure of O–TiN promotes the electrocatalytic conversion of sulfur species found in sulfur cathodes. Li–S cells that are prepared using the O–TiN@N-PGC as a sulfur host exhibit remarkable performance in terms of specific capacity (1408 mA h g −1 at 0.1 C), rate capacity (604 mA h g −1 at 4 C), and cycling stability (513 mA h g −1 after 1000 cycles at 0.5 C). Moreover, an areal capacity of 7.6 mA h cm −2 is achieved under a high sulfur loading of 5.7 mg cm −2 . The results establish a facile and efficient strategy for integrating metal nitrides in porous carbons , particularly for use in contemporary energy technologies.
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Journal of Oleo Science
·
2023
·
IF 1.5
Yuanyuan Zhang,You Li,Zhaoming Ran,Na Wang,Aicha Mekkaoui,Ce Wang,Li Zhao,Baocai Xu
Amino acid surfactants derived from animal/vegetable oils and amino acids have attracted growing interest in surfactant industry. The relationship between the molecular structures of natural building blocks and the performance of the derived surfactants has become a significant subject in their application. A series of serinate surfactants with different characteristic acyls were synthesized. The specific effect of the fatty acyl structures, namely, the hydrocarbon chain length, the number of C=C bonds, and hydroxyl substituent, on the foam properties and interfacial behaviors were revealed. The serinate surfactants with long fatty acyls showed better interfacial activity and were more closely arranged at the interface, thus improving the foam stability. But the long fatty acyls also decreased the water solubility, and lead to the decreased the foamability of N-stearyl serinate surfactant. The C=C bonds in the fatty acyl improved the water solubility of the surfactants. But multiple cis C=C bonds caused the bend of hydrocarbon chains, which was unfavorable for the close arrangement of surfactant molecules, thus leading to the decrease of the foam stability. The hydroxyl group in the ricinoleoyl decreased the intermolecular van der Waals interactions and hindered the close arrangement of ricinoleoyl serinate surfactant molecules, leading to the decrease of the foam stability.
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JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2023
·Vol. 34
·期 17
·1-10
·
IF 2.8
Wang Wenjun,Wu Jingxuan,Zou Song,Luo Qingsong,Wang Zhenxing,Wan Yu,Wang Yimu,Feng Changhao
In this study, LaFeO 3 nanotubes were created using the electrostatic spinning method and then calcined at various temperatures. Investigations into the impact of calcined temperatures on the morphological properties of LaFeO 3 nanotubes used a variety of methods. The results show that the surface of LaFeO 3 nanotubes gradually became rougher when the calcination temperature was above 700 °C, which could enhance the gas-sensitive properties of n-butanol. The response of LaFeO 3 nanotubes is 45.3–100 ppm n-butanol at 150 °C, and the low detection limit is 0.3 ppm. In addition, LaFeO 3 nanotubes calcined at 700 °C were found to have excellent selectivity for n-butanol. The mechanism of calcination temperature on the improvement of gas-sensitive properties of LaFeO 3 nanotubes was also proposed.
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JOURNAL OF MEMBRANE SCIENCE
·
2023
·
IF 9.5
Jin Du,Shuwei Liang,Meidi Wang,Yuhan Wang,Tianpei Yi,Zhiming Zhang,Fusheng Pan,Zhongyi Jiang
Facilitated transport membranes is a promising strategy to fabricate efficient separation membranes for aromatic/aliphatic mixtures. However, building up selective channels with uniformly distributed facilitated transport sites is still challenging. In this study, Cu-TAPB-COF (CuCOF) nanosheets , a kind of metal-covalent organic frameworks (MCOFs), were synthetized and introduced into poly (ether-block amide) (Pebax®2533) matrix to construct facilitated transport membranes for toluene/ n -heptane mixtures. As the aromatic skeleton linked by covalent interaction, CuCOF could provide continuous low mass transfer resistance channel. And Cu(I) exist in skeleton could serve as uniformly distributed facilitated transport sites and maintain a long-term stability. The resulting membrane exhibited a higher adsorption selectivity and lower swelling degree compared with pure Pebax membrane. The membrane exhibited high pervaporation separation performance for 50 wt% toluene/ n -heptane mixture. When the filling contents of CuCOF was 2.0 wt%, the membrane achieved a permeation flux of 937 g m −2 h −1 and the separation factor of 4.7.
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MOLECULES
·
2023
·Vol. 28
·期 12
·4633
·
IF 4.6
Yuyi Liao,Zhongtao Shang,Guangrui Ju,Dingke Wang,Qiao Yang,Yuan Wang,Shaojun Yuan
Developing advanced carbon materials by utilizing biomass waste has attracted much attention. However, porous carbon electrodes based on the electronic-double-layer-capacitor (EDLC) charge storage mechanism generally presents unsatisfactory capacitance and energy density. Herein, an N-doped carbon material (RSM-0.33-550) was prepared by directly pyrolyzing reed straw and melamine. The micro- and meso-porous structure and the rich active nitrogen functional group offered more ion transfer and faradaic capacitance. X-ray diffraction (XRD), Raman, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) measurements were used to characterize the biomass-derived carbon materials. The prepared RSM-0.33-550 possessed an N content of 6.02% and a specific surface area of 547.1 m2g−1. Compared with the RSM-0-550 without melamine addition, the RSM-0.33-550 possessed a higher content of active nitrogen (pyridinic-N) in the carbon network, thus presenting an increased number of active sites for charge storage. As the anode for supercapacitors (SCs) in 6 M KOH, RSM-0.33-550 exhibited a capacitance of 202.8 F g−1at a current density of 1 A g−1. At a higher current density of 20 A g−1, it still retained a capacitance of 158 F g−1. Notably, it delivered excellent stability with capacity retention of 96.3% at 20 A g−1after 5000 cycles. This work not only offers a new electrode material for SCs, but also gives a new insight into rationally utilizing biomass waste for energy storage.Keywords:biomass;supercapacitors;nitrogen doping;melamine;porous carbon
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EUROPEAN POLYMER JOURNAL
·
2023
·
IF 6
Huizi Zhang,Xu Zhao,Xiyue Wang,Yuchao Li,Shuangshuang Wang
Developing polyolefin microporous membranes with good antifouling ability and high separation efficiency is an important and urgent work. Herein, polypropylene microporous membranes (PP (mm)) containing zwitterionic polymer was prepared by grafting poly (sulfobetaine methacrylate) (PSBMA) onto the membrane via N-hydroxyphthalimide(NHPI) catalysis and activators regenerated by electron transfer atom transfer radical polymerization (ARGET-ATRP) for the first time. The structure, morphology, hydrophilicity and antifouling ability of PP (mm)-g-PSBMA was systematically studied. Water contact angle of the modified membrane could be sharply reduced at a proper grafting degree (GD), and it exhibited extraordinary hydrophilicity. The PP (mm)-g-PSBMA membrane also showed excellent protein antifouling ability and higher water flux compared to that of pristine PP membrane. Flux recovery ratio (FRR) of PP (mm)-g-PSBMA was increased to 93.1 % and relative flux reduction ratio (RFR) was decreased to 25.3%. This work presents a controllable and high efficiency strategy to polyolefin separation membrane for high value products.
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