NANOTECHNOLOGY
·
2020
·Vol. 31
·期 14
·145601
·
IF 3.551
Rui Li,Xinyan Li,Ping-An Yang,Haibo Ruan
High-performance iron nanowires have attracted wide attention from researchers due to their 'controllable' arrangement distribution by magnetic fields. In this paper, a simple magnetic field assisted in situ reduction method was proposed to synthesize Fe NWs with high aspect ratio, small-diameter, and good dispersion. A detailed parametric study determining the relationship among the final morphologies of the products and magnetic field, injection sequence of sodium borohydride that was injected into ferrous sulfate heptahydrate, reactant concentration, and injection rate is presented. The as-synthesized Fe NWs were analyzed by scanning electron microscopy, transmission electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy and vibrating sample magnetometry. A plausible mechanism for the formation of high-aspect-ratio Fe NWs is proposed. The SEM images showed the dependence of the NWs morphology and aspect ratio on synthesis parameters. Magnetic field and injection sequence showed considerable influences on the synthesis of high-aspect-ratio Fe NWs. In the absence of magnetic field or with the changes in injection sequence, only the Fe flakes were obtained. The NWs diameter decreased, and the aspect ratio increased with the increase in injection rate. The FeSO4·7H2O and NaBH4 concentration considerably influenced the aspect ratio of the product, which increased first, decreased, and then increased again with the increase in FeSO4·7H2O concentration. Meanwhile, the product aspect ratio increased and then became saturated with the increase in NaBH4 concentration Thus, an optimum synthesis process was obtained, with the average aspect ratio of 350, and the average diameter of 60 nm. The results reported in this paper provide a basis for optimizing the growth of Fe NWs by magnetic field-assisted method.
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ACS Applied Nano Materials
·
2024
·
IF 5.3
Weiqing Wu,Luchan Lin,Yifan Hu,Junde Ji,Xinde Zuo,Yiwei Yu,Qianyi Zhang,Zhengjie Cai,Zhuguo Li
Ultralong graphene nanoribbons (GNRs) have drawn much attention in the field of high performance nanoelectronics. In this work, a mask-free ultrafast laser lithography method is demonstrated for the mass production of ultralong GNR arrays with an intact carbon network. The longest GNR reaches ∼42 μm with a width of ∼400 nm. The orientation of the as-received GNR arrays is always parallel to the incident laser polarization direction. Original carbon network structures of remaining GNRs are preserved, which are ascribed to the precise energy injection and selective nanoablation in graphene flakes. The formation of large-scale GNR arrays is mainly determined by the interference between the incident laser and the stimulated transverse electric mode surface plasmon (TE-SPs) wave. The excitation of the TE-SPs wave prefers to be triggered at the geometrical fluctuations on ablated graphene surfaces as well as the interface with a large discrepancy of dielectric permittivity (e.g., graphene and SiO2). With the initial generation of the nanoablated groove on the surface, the interference between TE-SPs waves and incident laser beams further extends to the far end with periodic intervals, which results in the continuous formation of GNRs. This ultrafast laser-induced periodic lithography may provide an alternative for ultralong and high aspect ratio GNR array fabrication, which is promising in high performance nanodevice development.
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CARBOHYDRATE POLYMERS
·
2026
·
IF 13.2
Chenchen Shen,Weiwei Chen,Lin Guo,Yanrui Zou,Shuan Han,Ning Yu,Lin Gan,Jin Huang
Long-range piezoelectric transduction in flexible hydrogels is limited by the “trade-off” of conductive pathways between accelerating charge dissipation and suppressing dipole formation. Here, we introduce a surface-heterojunction strategy converting cellulose nanocrystals (CNCs) into conductive dipolar nanorods by deprotonation of poly(aminophenylboronic acid) (PABA) coating. Boronated ester bonding and hydrogen-bonds at CNCs/PABA interface collectively strengthen dipole moments while inducing n-type doping in PABA and thus enabling charge transport for 18.9-fold conductivity. Integrating molecular-level interfacial alignment of conjugated moieties, CNCs with higher aspect-ratio further promote percolation and reduce threshold by ~14%. The charge transport range in hydrogel is then elongated, which improves its conductivity by 7.0 times and yields robust piezo-electric/resistive dual-mode responsiveness. The hydrogen-bond network also improves adhesion, and imparts intrinsic sensitivity to temperature, salinity, and pH, for distinguishing complex motions and physiological events. This heterojunction-driven co-engineering of dipoles and conductivity offers a generalizable materials concept for advancing high-fidelity soft bioelectronic sensing.
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International Journal of Electrochemical Science
·
2023
·
IF 1.5
Yuehong Pang,Qiufang Zhang,Xiulan Sun,Jian Ji,Fuwei Pi,Xiaofang Shen
Inspired from the pathogenic process of diphenylalanine (FF) self-assembly, a key structural motif in forming Alzheimer’s β-amyloid peptide fibrils, a facile way for preparation of FF aromatic dipeptide fibrils and fabrication of an electrochemical biosensor were developed. Long persistence length FF fibrils with ultra-high aspect ratio over 1000 were obtained using cationic surfactant assisted evaporation induced self-assembly. The Cotton effects indicate a signature of dominant β-sheet arrangement and the thickness of the β-sheet monolayer is estimated to be 2.38 nm. The obvious blue-shift of intrinsic fluorescence indicates an extended H-aggregate between the phenyl rings in a parallel mode. The FF fibrils based electrochemical biosensor, taking horseradish peroxidase as a model enzyme, displayed an excellent electrocatalytic activity to the reduction of H 2 O 2 . The peak current was a linear function of concentrations ranging from 7.5×10 -7 to 1.4×10 -5 M, with a detection limit of 2.5×10 -7 M. The apparent Michaelis-Menten constant was 7.2 μM. These results indicate that the FF fibrils with ultra-high aspect ratio providing a new and promising platform for construction of electrochemical biosensors.
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ELECTROCHIMICA ACTA
·
2022
·
IF 7.336
Qing Wang,Jiaxin Liu,Zhenyu Lei,Yun Mou,Mingxiang Chen
In this work, we combined the computational simulation and experiments to explore the convection on filling characteristics of the micro through-holes (THs) with multiple aspect ratio (ARs). The micro THs with ARs 6.25:1∼1.67:1 (thickness 500 μm) were chosen as research targets. The computational model was established based on the actual state of Haring-Cell, and attention was fixed on the convection distribution in the micro THs. The interaction mechanism of additives with the changing ARs systematically explored by electrochemical measurements. The simulation results show that the convection in the micro THs center declines with the increasing AR. The convection-dependent additives formed diverse adsorption states around the micro THs with different ARs, providing two kinds of Cu filling processes, including defect-free filling and insufficient filling. The weak convection is conducive to the adsorption of the accelerator and detrimental to the adsorption of the suppressor, which accelerates the Cu electrodeposition and elevates the throwing power (TP) value to over 100% to form the defect-free filling. Strong convection is instrumental in the adsorption of the leveler so that a uniform Cu film thickness can be obtained but to create the insufficient filling. Simulation and electroplating experiments show that the AR of 3.33:1 is the cut-off point of the flow field distribution and the electroplating processes. The micro THs with AR higher than 3.33:1 can be fully filled with a uniform bright Cu surface.
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ACS Nano
·
2021
·
IF 15.881
Qingwei Yan,Wen Dai,Jingyao Gao,Xue Tan,Le Lv,Junfeng Ying,Xiaoxin Lu,Jibao Lu,Yagang Yao,Qiuping Wei,Rong Sun,Jinhong Yu,Nan Jiang,Ding Chen,Ching-Ping Wong,Rong Xiang,Shigeo Maruyama,Cheng-Te Lin
The rapid development of integrated circuits and electronic devices creates a strong demand for highly thermally conductive yet electrically insulating composites to efficiently solve “hot spot” problems during device operation. On the basis of these considerations, hexagonal boron nitride nanosheets (BNNS) have been regarded as promising fillers to fabricate polymer matrix composites. However, so far an efficient approach to prepare ultrahigh-aspect-ratio BNNS with large lateral size while maintaining an atomically thin nature is still lacking, seriously restricting further improvement of the thermal conductivity for BNNS/polymer composites. Here, a rapid and high-yield method based on a microfluidization technique is developed to obtain exfoliated BNNS with a record high aspect ratio of ≈1500 and a low degree of defects. A foldable and electrically insulating film made of such a BNNS and poly(vinyl alcohol) (PVA) matrix through filtration exhibits an in-plane thermal conductivity of 67.6 W m–1 K–1 at a BNNS loading of 83 wt %, leading to a record high value of thermal conductivity enhancement (≈35 500). The composite film then acts as a heat spreader for heat dissipation of high-power LED modules and shows superior cooling efficiency compared to commercial flexible copper clad laminate. Our findings provide a practical route to produce electrically insulating polymer composites with high thermal conductivity for thermal management applications in modern electronic devices.
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ANALYTICA CHIMICA ACTA
·
2021
·
IF 6.558
Xiaojuan Zhou,Qiang Liu,Xiaoyu Shi,Chunli Xu,Baoxin Li
In this work, three kinds of gold nanorods (AuNRs) with different aspect ratios were synthesized through conventional seed-mediated growth method, and the chirality of these AuNRs were characterized by circular dichroism (CD) spectroscopy. The results showed that the AuNRs with bigger aspect ratio had larger chirality. The AuNRs with different aspect ratios were applied to distinguish the enantiomers of 19 kinds of α -amino acids. It was found that AuNRs with bigger aspect ratio exhibited the stronger chiral recognition ability. As a proof-of-principle, the AuNRs with the aspect ratio of 4.8 were used to quantitatively recognize enantiomers of valine . Furthermore, the microcalorimetry was applied to study the interaction of AuNRs with amino acid enantiomers. This work provides one method to improve the chiral recognition ability of AuNRs by optimizing the aspect ratio of AuNRs, and helps people better understand the intrinsic chirality of nanostructures .
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JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2021
·Vol. 32
·期 12
·15622-15632
·
IF 2.478
Zhai Xin,Wang Wenxian,Jia Jing,Dong Peng
Silver nanowires (AgNWs) are promising candidate materials for flexible transparent conductive films (FTCFs), which are key parts in fabricating flexible optoelectronic devices. In the present work, we developed a modified polyol method, allowing simple and rapid synthesis of AgNWs with an ultra-high aspect ratio up to 2600, by adjusting the concentration of Cl − and Br − . Further, AgNWs–mixed cellulose ester membrane (MCE) FTCFs by vacuum filtration method were fabricated, exhibiting low sheet resistance of 6.53 Ω/sq and transmittance of 83.20%, which are comparable to those of typical indium tin oxide electrodes. Also, mechanical robustness results show the sheet resistance of the AgNWs–MCE film increased 16 and 2.8% after 300 times bending tests and 100 times of adhesion tests, respectively.
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ACS Applied Materials & Interfaces
·
2020
·
IF 8.758
Mingqi Chen,Yankai Pan,Zhe Su,Donghui Long
Porous carbon nanosheets (PCNs) with a large two-dimensional morphology and high porosity have emerged as an important class of 2D materials, while developing novel technology to manufacture high-quality PCNs in terms of convenience, high output, and economic benefit remains a challenge. Herein, a rapid gas-engineering technology is developed to fabricate graphene-like mesoporous carbon nanosheets (MCNs) with large aspect ratios (>2500, length/thickness). By easy carbonization of calcium gluconate under reduced pressure, MCNs with ultrathin (∼12 nm) thickness, ultralarge (>20 μm) lamella morphology, and high surface area (∼1155 m2/g) are fabricated in kilogram scale. Two-dimensional lamella morphology transformation, pore architectures, and calcium compounds transformation mechanisms are unraveled by in situ variable temperature X-ray diffraction (VT-XRD), high-resolution transmission electron microscopy (HRTEM), ex situ scanning electron microscopy (SEM), and atomic force microscopy (AFM). The key to the synthesis is the negative pressure operation, which triggers the rapid gas expansion in a gas–solid system. This design relied on the gas expansion mechanism has realized producing of high-quality MCNs via a rapid, high-throughput, and cost-effective way. Due to high surface utilization and low weight density, when served as a lightweight separator coating layer, MCNs exhibit impressive capture ability toward polysulfides and achieve a high-stability lithium–sulfur battery.
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ACS Applied Materials & Interfaces
·
2016
·
IF 7.145
Wen She,Han Bi,Zhiwei Wen,Qinghe Liu,Xuebing Zhao,Jie Zhang,Renchao Che
A tunable response frequency is highly desirable for practical applications of microwave absorption materials but remains a great challenge. Here, hollow lightweight polydopamine@α-MnO2 microspindles were facilely synthesized with the tunable absorption frequency governed by the aspect ratio. The size of the hard template is a key factor to achieve the unique shape; the polymer layer with uniform thickness plays an important role in obtaining spindles with homogeneous size. With the aspect ratio increasing, the maximum reflection loss, as well as the absorption bandwidth (<−10 dB), increases and then decreases; meanwhile, the microwave absorption band shifts to the low frequency. The optimized aspect ratio of the cavity about the hollow polydopamine@α-MnO2 microspindles is ∼2.8. With 3 mm thickness at 9.7 GHz, the strongest reflection reaches −21.8 dB, and the width of the absorbing band (<−10 dB) is as wide as 3.3 GHz. Via electron holography, it is confirmed that strong charge accumulates around the interface between the polydopamine and α-MnO2 layers, which mainly contributes to the dielectric polarization absorption. This study proposes a reliable strategy to tune the absorption frequency via different aspect ratio polymer@α-MnO2 microspindles.
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CRYSTENGCOMM
·
2017
·Vol. 19
·期 24
·3263-3270
·
IF 3.474
He Ding,Xiuxiu Ni,Yixiao Zhang,Jingshuang Zhang,Zhouliangzi Zeng,Menglin Qi,Peng Bai,Xianghai Guo
High-aspect ratio b-oriented MFI nanosheets are synthesized by simply adding a suitable amount of graphene oxide (GO) nanosheets into a multilamellar MFI zeolite crystallization system. The GO nanosheets, serving as the building blocks for oriented attachment and in situ nucleation sites, positively induce the silicalite-1 nanosheet crystallization process and confine the over-growth of MFI crystals during the subsequent preparation. A two-dimensional (2D) induction mechanism of the GO nanosheets is discussed for the generation of the b-oriented MFI nanosheets. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), nitrogen adsorption, Fourier transform infrared (FT-IR) spectroscopy and thermogravimetric analysis (TGA).
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CHEMICAL ENGINEERING JOURNAL
·
2025
·
IF 13.2
Weilong Wu,Tianzhuo Zhan,Peng Wang,Zexia Li,Bo Li,Lu Meng,Zifeng Niu,Shijie Ma,Haoran Chen,Jun Zhang,Jahangeer Ahmed,Chengchun Tang,Yanming Xue
In the development of hexagonal boron nitride ( h -BN)/polymer composites, it is expected that efficient thermal transport networks constructed by the desired high-aspect-ratio (HAR) h -BN nanosheets (BNNSs) can be formed within them, thereby enhancing their heat dissipation capacity. In this work, a new and facile fusing-smashing method was developed to exfoliate h -BN. This method produces BNNSs with an outstanding aspect ratio of about 2200. Using these HAR-BNNSs as fillers, a series of BNNSs-based polymer composites were developed in the form of bulks, films, and adhesives with high thermal conductivity (TC) and mechanical performance. The maximum room temperature TC and compressive strength values of the formed 30BNNSs/rosin bulk composites are 3.13 ± 0.08 Wm -1 k −1 and 64 MPa, respectively. They show 62.6 times and 3.6 times the performance of the blank rosin. The in-plane TC and tensile strength of the 22BNNSs/Polyimide (PI) films are 14.4 ± 0.1 Wm -1 k −1 and 60 MPa, respectively, which are higher than those of the blank PI film (0.18 Wm -1 k −1 and 30 MPa). Noteworthy, compared to the blank adhesive of SMT (soyoil-malate-tannin), the TC of the prepared 2.5BNNSs/R/SMT composite adhesive is increased by 3.7 times, while its bonding strength also exhibits a 22 % enhancement, with only 2.5 wt% HAR-BNNSs filling fraction. In addition, all the HAR-BNNSs-filled composite materials manifest exceptional thermal diffusivity, indicating their potential for widespread application in thermal management for modern electronic devices.
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