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Hoang Anh Nguyen,Thi Nam Pham,Le Thanh Nguyen Huynh,Tran Ha Trang Nguyen,Viet Hai Le,Nguyen Thai Hoang,Thi Thom Nguyen,Thi Thu Trang Nguyen,Dai Lam Tran,Thi Mai Thanh Dinh The Korean Electrochemical Society 2024 Journal of electrochemical science and technology Vol.15 No.2
Due to its high theoretical capacity, Silicon (Si) has shown great potential as an anode material for lithium-ion batteries (LIBs). However, the large volume change of Si during cycling leads to poor cycling stability and low Coulombic efficiency. In this study, we synthesized Si/Carbon C45:Graphene composites using a ball-milling method with a fixed Si content (20%) and investigated the influence of the C45/Gr ratio on the electrochemical performance of the composites. The results showed that carbon C45 networks can provide good conductivity, but tend to break at Si locations, resulting in poor conductivity. However, the addition of graphene helps to reconnect the broken C45 networks, improving the conductivity of the composite. Moreover, the C45 can also act as a protective coating around Si particles, reducing the volume expansion of Si during charging/discharging cycles. The Si/C45:Gr (70:10 wt%) composite exhibits improved electrochemical performance with high capacity (~1660 mAh g<sup>-1</sup> at 0.1 C) and cycling stability (~1370 mAh g<sup>-1</sup> after 100 cycles). This work highlights the effective role of carbon C45 and graphene in Si/C composites for enhancing the performance of Si-based anode materials for LIBs.
Control of morphology and Orientation of Electrochemically Grown ZnO Nanorods
Tran Hoang Cao Son,Le Khac Top,Nguyen Thi Dong Tri,Ha Thuc Chi Nhan,Lam Quang Vinh,Bach Thang Phan,김상섭,Le Van Hieu 대한금속·재료학회 2014 METALS AND MATERIALS International Vol.20 No.2
We report the direct electrochemical deposition of ZnO nanorods on an indium tin oxide substrate. Themorphology and orientation of the grown ZnO nanorods were investigated as functions of the currentdensity. It is likely that the concentrations of OH- and Zn2+ ions, which could be controlled by varying thecurrent density, determine the shape and alignment of the ZnO nanorods. The nanorods were tilted, hexagonal,and prismatic at a low current density (0.1 mA/cm2) and vertically aligned and obelisk-shaped at highcurrent densities (greater than 0.6 mA/cm2). By using the low and high current densities sequentially in atwo-step growth process, vertically aligned, hexagonal, and prismatic ZnO nanorods could be grownsuccessfully. The underlying mechanism responsible for the growth of the ZnO nanorods is also discussed.
Thu Ha Nguyen,Thi Lan Pham,Anh Quan Cao,Tuan Anh Nguyen,Xuan Minh Vu,Thi My Hanh Le,Van Thuan Le,Seiichi Kawahara,Dai Lam Tran 한국고분자학회 2024 Macromolecular Research Vol.32 No.4
This study describes the preparation and characterization of a green and safe membrane based on a natural polymer for metal adsorption. Natural rubber-grafted-(2-hydroxyethyl methacrylate) with a special nanostructure was synthesized by graft copolymerization of 2-hydroxyethyl methacrylate (HEMA) onto the surface of natural rubber (NR) particles using tert-butylhydroperoxide/tetraethylenepentamine as initiators. Optimal conditions for achieving high conversion and grafting efficiency were identified. Characterization of the as-synthesized samples was performed using Fourier-transform infrared spectroscopy, transmission electron microscopy, thermogravimetric analysis, tensile measurement, swelling degree determination, and cytotoxicity testing. The results revealed that HEMA formed a nanoscale matrix surrounding NR particles, which improved the tensile strength, thermal resistance, and swelling degree of the as-prepared samples. Cytotoxicity testing demonstrated that the membrane was safe for human use, as it did not exhibit toxicity to Vero cells at concentrations up to 1024 μg/mL. Furthermore, the membrane displayed a high adsorption capacity toward Fe3+ and was well described by Koble-Corrigan isotherm model and the first–second-order kinetic equation. Moreover, the membrane demonstrated excellent recyclability maintaining its adsorption ability towards Fe3+ ions over five consecutive cycles. Overall, these findings may recommend the NR-HEMA membrane as a promising candidate for metal removal applications.