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Paveena Laokul,Vittaya Amornkitbamrung,Supapan Seraphin,Santi Maensiri 한국물리학회 2011 Current Applied Physics Vol.11 No.1
This study reports the simple synthesis of MFe_2O_4 (where M = Cu, Ni, and Zn) nanoparticles by a modified sol-gel method using high purity metal nitrates and aloe vera plant extracted solution. Using of aloe vera extract simplifies the process and provides an alternative process for a simple and economical synthesis of nanocrystalline ferrites. The obtained precursors were characterized by TG/DTA to determine the thermal decomposition and subsequently were cc at different temperatures in the range of 600―900 ℃ for 2 h to obtain the ferrite nanoparticles. The calcined samples were characterized by XRD, FT-IR, SEM, and TEM. All the prepared samples are polycrystalline and have spinel structure with crystallite sizes of 15―70 nm. The crystallite size increases with increasing the calcination temperature. Magnetic properties of the prepared ferrite samples were measured using Vibrating sample magnetometer (VSM). The room temperature magnetic behavior of as-prepared ferrite powders can be explained as the results of the three important factors: impurity phase of a-Fe_2O_3, cationic distribution in spinel structure, and the surface spin structure of nanoparticles.
( Panitat Hasin ),( Vittaya Amornkitbamrung ),( Narong Chanlek ) 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1
Nanocomposites of cobalt or nickel species and N-doped mesoporous carbon as well as tungsten carbide imbedded in N-doped hierarchical hollow mesoporous carbon were prepared for replacing Pt as the electrocatalysts on the counter electrodes (CEs) of dye-sensitized solar cells (DSCs). It is shown that the obtained nanocomposite carbon materials significantly improve the electrocatalytic activity toward the reduction of I<sub>3</sub><sup>-</sup> compared to bared porous carbons. The prepared nanocomposite carbon materials with enhanced electrochemical stability are the benefit to combining high electrical conductivity and electrocatalytic activity into one material in which Co or Ni species as well as WC serve as the electrocatalysts and N-doped mesoporous carbon as well as N-doped hierarchical hollow mesoporous carbon serves as the electrical conductors. The fabricated nanocomposite carbon materials based DSCs show the best light-to-electricity conversion efficiency (η) which are higher than those of the cells with bared porous carbons CEs and are comparable to that of the cell with a platinized CE.
Effect of Fabrication Method on the Structural and the Magnetic Properties of Copper Ferrite
Siriwipa Pongpadung,Teerasak Kamwanna,Vittaya Amornkitbamrung 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.68 No.5
Copper ferrites (CuFe2O4) were fabricated by using the self-combustion urea and glycine process (UNP, and GNP), the polymerized complex (PC), the solid-state reaction (SSR), and the molten-salt (MS) methods. The synthesized powders were calcined in static air at different temperature from 773 to 1173 K. The effects of the fabrication method on the microstructural and the magnetic properties were investigated. X-ray diffraction (XRD) analysis results revealed the cubic CuFe2O4 spinel structure for the original powders. The tetragonal CuFe2O4 spinel structure was obtained after calcination. Vibrating sample magnetometry (VSM) showed significant changes in the magnetic properties of the CuFe2O4 system with fabrication method, phase composition, and heat treatment.
Ni3S2@MWCNTs films for effective counter electrodes of dye-sensitized solar cells
Wasan Maiaugree,Tana Tansoonton,Vittaya Amornkitbamrung,Ekaphan Swatsitang 한국물리학회 2019 Current Applied Physics Vol.19 No.12
Composite films nickel sulfide (Ni3S2) nanoparticles were grown on multiwall carbon nanotubes (MWCNTs) and in situ coated onto conducting glass substrates by the hydrothermal process at 170 °C. These Ni3S2@MWCNTs films were applied for counter electrodes (CEs) of dye-sensitized solar cells (DSSCs). In this work, nanostructure, crystalline structure, electrochemical activities and electron-charge transfer resistance of CEs were studied. In addition, the effective surface areas of CEs were analyzed and discussed as well. The power conversion efficiency (PCE) enhancement of up to 7.48%, compared with that of Ni3S2-DSSC, was demonstrated for a Ni3S2@MWCNTs DSSC.
Natkrita Prasoetsopha,Supree Pinitsoontorn,Vittaya Amornkitbamrung 대한금속·재료학회 2012 ELECTRONIC MATERIALS LETTERS Vol.8 No.3
Thermoelectric Ca3Co4O9 powders were synthesized by a simple thermal hydro-decomposition method, which is novel, simple and cost effective for preparing such materials. The stoichiometric ratio of the acetate salts was mixed in de-ionized water and heated at 1073 K to obtain a single phase of Ca3Co4O9, which was confirmed by TG-DTA, XRD and chemical analysis. The electron micrograph showed plate-like particles with a diameter of ~1 μm. The hot-pressed powders show the electrical resistivity of 11.6 mΩcm, the Seebeck coefficient of 200 μV/K, and the thermal conductivity of 1.2 Wm−1K−1 at 880 K, which corresponds to a dimensionless figure-of-merit ZT of 0.23.
Enhanced Specific Capacitance of an Electrophoretic Deposited MnO2-Carbon Nanotube Supercapacitor
Patin Tagsin,Pawinee Klangtakai,Viyada Harnchana,Vittaya Amornkitbamrung,Samuk Pimanpang,Pisist Kumnorkaew 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.71 No.12
MnO2 and MnO2-carbon nanotubes (CNT) composite films were grown directly on stainless- steel substrates using an electrophoretic process employing supercapacitor electrodes. An electrophoretic MnO2 film with a nanoplate-like structure was observed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Supercapacitor performance was studied using cyclic voltammetry (CV), charge-discharge (CD) and electrochemical impedance spectroscopy (EIS). The specific capacitance (SC) of the electrophoretic MnO2 film was 60 F/g at 1 A/g, with a 38.33% retention of the initial SC values after 1000 cycles. The low SC value of the MnO2 films was attributed to the high series and charge-transfer resistances of 1.70 and 3.20, respectively. The MnO2-CNT composites with the addition of 0.04, 0.06 and 0.08 g CNT to the electrophoretic MnO2 film were found to greatly increase the SC to 300, 206 and 169 F/g at 1 A/g, respectively. The series and charge-transferred resistances of MnO2-CNT composite films decreased to 1.38 - 1.52 and 2.62 - 2.86 , respectively. The SC improvement of the composite electrodes was attributed to presence of two active storage materials (MnO2 and CNT), a high film specific surface area and electrical conductivity.
Anongnad Thiangkaew,Khamsone Keothongkham,Wasan Maiaugree,Wirat Jarernboon,Teerasak Kamwanna,Samuk Pimanpang,Vittaya Amornkitbamrung 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.64 No.9
Platinum, polyaniline and composite polyaniline-platinum films were coated on conductive glassby using electrochemical deposition. They were then used as dye-sensitized solar cell counter electrodes. The efficiencies of platinum, polyaniline and composite polyaniline-platinum cells were 2.47,4.47 and 6.62%, respectively. The improvement of composite polyaniline-platinum solar cell efficiencyover pure polyaniline and platinum cells is because of an increase in the film’s catalyticactivity and a decrease in charge-transfer resistance between its counter electrode and electrolyte,as observed by using cyclic voltammogram and electrochemical impedance spectroscopy measurements,respectively. Co-deposition of polyaniline and Pt catalysts was confirmed by the presenceof Pt and N peaks in the X-ray photoelectron spectroscopy spectrum.
Harnchana, Viyada,Ngoc, Huynh Van,He, Wen,Rasheed, Aamir,Park, Hyunje,Amornkitbamrung, Vittaya,Kang, Dae Joon American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.30
<P>In this work, a new approach to modifying poly(dimethylsiloxane) (PDMS) as a negative triboelectric material using graphene oxide (GO) and a sodium dodecyl sulfate (SDS) surfactant was reported. A porous PDMS@GO@SDS composite triboelectric nanogenerator (TENG) could deliver an output voltage and current of up to 438 V and 11 μA/cm<SUP>2</SUP>, respectively. These values were 3-fold higher than those of the flat PDMS. The superior performance is attributed to the intensified negative charges on PDMS from the oxygen functional groups of GO and anionic head groups of the SDS molecules. The outstanding performance and straightforward, low-cost fabrication process of the PDMS@GO@SDS TENG would be beneficial for the further development of powerful NGs integrated into wearable electronics and self-charging power cells.</P> [FIG OMISSION]</BR>
Patin Tagsin,Pawinee Klangtakai,Viyada Harnchana,Samuk Pimanpang,Vittaya Amornkitbamrung 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.12
MnO2 films were hydrothermally grown directly onto stainless-steel substrates and used as supercapacitor electrodes. MnO2 with a cube-like structure was observed by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The measured sizes of the cubes were in the range of 270 − 820 nm. The specific capacitance (SC) of the 5-hour hydrothermallygrown MnO2 films was 20.2 F/g, which was slightly higher than that of the 3-hour films (13.8 F/g). The low values of the SC of the hydrothermally-deposited MnO2 films are attributed to their high series resistances of 1.73 − 2.06 measured by using electrochemical impedance spectroscopy. However, the specific capacitance was greatly increased, up to 226 F/g, after a polyaniline polymer had been added into the MnO2 hydrothermal reaction, there by producing a composite of the MnO2 and the polyaniline polymer. This SC improvement was attributed to presence of two active materials (polyaniline and MnO2) and the reduction of the electrode series resistance to 0.93 .
Samuk Pimanpang,Madsakorn Towannang,Pantiwa Kumlangwan,Wasan Maiaugree,Kunthaya Ratchaphonsaenwong,Viyada Harnchana,Wirat Jarenboon,Vittaya Amornkitbamrung 대한금속·재료학회 2015 ELECTRONIC MATERIALS LETTERS Vol.11 No.4
Pt-free TiC based electrodes were hydrothermally deposited onto FTO/ glass substrates and used as dye-sensitized solar cell (DSSC) counter electrodes. A promising efficiency of 3.07% was obtained from the annealed hydrothermal TiC DSSCs based on a disulfide/thiolate electrolyte. A pronounced improvement in performance of 3.59% was achieved by compositing TiC with carbon, compared to that of a Pt DSSC, 3.84%. TEM analysis detected that the TiC particle surfaces were coated by thin carbon layer (7 nm). The SAED pattern and Raman spectrum of TiC-carbon films suggested that the carbon layer was composed of amorphous and graphite carbon. The formation of graphite on the TiC nanoparticles plays a crucial role in enhancing the film’s reduction current to 10.12 mA/cm2 and in reducing the film impedance to 237.63 Ω, resulting in a high efficiency of the TiC-carbon DSSC.