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  • Authors: Chu, Manh Hung;  Advisor: Han, Viet Phuong; Vu, Van Thinh; Le, Thi Hong; Nguyen, Tat Thang; Nguyen, Hong Hanh; Nguyen, Quang Dich; Nguyen, Van Hieu; Nguyen, Van Duy; Nguyen, Duc Hoa;  Co-Author: - (2021)

    Nanofibers of ZnO-SnO2 nanocomposites doped with Au crystals were synthesized by an electrospinning method for enhancement of H2S gas sensing performance. The mixed solution of zinc acetate dihydrate and tin(II) chloride dihydrate, dissolved in ethanol/DMF solvent, was spun directly on the interdigital Pt electrodes for sensor fabrication. Thermal treatment was carried out to convert the spun nanofibers into ZnO-SnO2 nanocomposites doped with Au crystals. SEM and TEM observation confirmed the formation of porous nanofibers with an average diameter of about 120 nm. X-ray diffraction studies revealed that the nanocomposites of ZnO and SnO2 phases were formed, but not ZnSnO3, despite the precursor solution being mixed on the atomic scale from the starting solution. Doping with 0.001, 0...

  • Authors: Nguyen Ngoc Viet;  Advisor: Le Viet Thong; Tran Khoa Dang; Phan Hong Phuoc; Nguyen Hong Chien; Chu Manh Hung; Nguyen Duc Hoa; Nguyen Van Duy; Nguyen Van Toan; Nguyen Tang Son; Nguyen Van Hieu;  Co-Author: - (2021)

    The effect of MoS2 nanosheet (NS) decoration on the gas-sensing properties of SnO2 nanofibers (NFs) was investigated. The decorated sensors were fabricated by facile on-chip electrospinning technique and subsequently dropping MoS2 NSs-dispersed solution. The MoS2 NS decoration resulted in enhanced the response and reduced the operating temperature of SnO2 NFs towards SO2 gas. The SnO2 NF sensor decorated with the optimum density of MoS2 NSs exhibited about 10-fold enhancement in gas response to 10 ppm SO2 at 150 °C as compared with the bare SnO2 NF sensor. Furthermore, the decorated sensors exhibited an extremely low detection limit and good selectivity for SO2 gas against other interfering gases, such as CO, NH3, and H2. The enhanced SO2 gas-sensing performance of MoS2 NSs-decorate...

  • Authors: Duc-Nam Nguyen; Van-Tuan Nguyen; Ich-Hung Dam; Van-Huong Vu;  Advisor: -;  Co-Author: - (2022)

    A large number of piezoelectric polymers have been studied and applied widely recently and become an attractive topic in both material science and applied engineering fields. Piezoelectric polymers such as Poly(vinyl fluoride) and Poly(γ-benzyl, L-glutamate) fabricated in nanofibers have shown impressive properties in the aspect of low weight, high flexibility and high piezoelectricity. One of the major parameters influencing to the piezoelectricity of electrospun fibers is the orientation. This paper reviews the contribution of fiber orientation to the piezoelectricity properties and the technique to manipulate the orientation. The research group introduces for the first time a fully integrated and compact electrospinning system which is low cost and suitable for both lab-scale and...

  • Authors: Nguyen, Duc Nam; Wonkyu, Moon;  Advisor: -;  Co-Author: - (2022)

    Electrospinning is a low-cost and straightforward method for producing various types of polymers in micro/nanofiber form. Among the various types of polymers, electrospun piezoelectric polymers have many potential applications. In this study, a new type of functional microfiber composed of poly(γ-benzyl-α,L-glutamate) (PBLG) and poly(vinylidene fluoride) (PVDF) with significantly enhanced electromechanical properties has been reported. Recently reported electrospun PBLG fibers exhibit polarity along the axial direction, while electrospun PVDF fibers have the highest net dipole moment in the transverse direction. Hence, a combination of PBLG and PVDF as a core–shell structure has been investigated in the present work. On polarization under a high voltage, enhancement in the net dipol...

  • Authors: Duc-Nam Nguyen; Wonkyu, Moon;  Advisor: -;  Co-Author: - (2022)

    Electrospinning is a low-cost and straightforward method for producing various types of polymers in micro/nanofiber form. Among the various types of polymers, electrospun piezoelectric polymers have many potential applications. In this study, a new type of functional microfiber composed of poly(γ-benzyl-α,L-glutamate) (PBLG) and poly(vinylidene fluoride) (PVDF) with significantly enhanced electromechanical properties has been reported. Recently reported electrospun PBLG fibers exhibit polarity along the axial direction, while electrospun PVDF fibers have the highest net dipole moment in the transverse direction. Hence, a combination of PBLG and PVDF as a core–shell structure has been investigated in the present work. On polarization under a high voltage, enhancement in the net dipol...

  • Authors: Nguyen, Duc Nam; Nguyen, Van Tuan; Dam, Ich Hung; Vu, Van Huong;  Advisor: -;  Co-Author: - (2022)

    A large number of piezoelectric polymers have been studied and applied widely recently and become an attractive topic in both material science and applied engineering fields. Piezoelectric polymers such as Poly(vinyl fluoride) and Poly(γ-benzyl, L-glutamate) fabricated in nanofibers have shown impressive properties in the aspect of low weight, high flexibility and high piezoelectricity. One of the major parameters influencing to the piezoelectricity of electrospun fibers is the orientation. This paper reviews the contribution of fiber orientation to the piezoelectricity properties and the technique to manipulate the orientation. The research group introduces for the first time a fully integrated and compact electrospinning system which is low cost and suitable for both lab-scale and...

  • Authors: Phuoc, Phan Hong;  Advisor: Hong, Le Thi; Thang, Nguyen Tat; Hanh, Nguyen Hong; Hung, Chu Manh; Duy, Nguyen Van; Hieu, Nguyen Van; Hoa, Nguyen Duc;  Co-Author: - (2021)

    In the current work, we report the on-chip fabrication of a low-temperature H2S sensor based on p-type Co3O4 nanofibers (NFs) using the electrospinning method. The FESEM images show the typical spider-net like morphologies of synthesized Co3O4 NFs with an average diameter of 90 nm formed on the comb-like electrodes. The EDX data indicate the presence of Co and O elements in the NFs. The XRD analysis results confirm the formation of single-phase cubic spinel nanocrystalline structures (Fd3 m) for the synthesized Co3O4 NFs. The Raman results are in agreement with the XRD data through the presence of five typical vibration modes of the nanocrystalline Co3O4. The gas sensing properties of the fabricated Co3O4 NF sensors are tested to 1 ppm H2S within a temperature range of 150 °C to 450...