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    Electrochemical performance of Bi2Te3 heterostructure thin film and Cu7Te4 nanocrystals on undoped and In3+-doped WO3 films for energy storage applications
    (2020-05-01)
    Buathet, Supitchaya
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    Simalaotao, Kodchakorn
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    Reunchan, Pakpoom
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    Vailikhit, Veeramol
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    Teesetsopon, Pichanan
    We demonstrated the synthesis of undoped and In<sup>3+</sup>-doped WO<inf>3</inf> as an electron acceptor for energy storage applications, by utilizing the electrochemical S<sup>2−</sup> insertion/extraction process at the heterostructure of rhombohedral Bi<inf>2</inf>Te<inf>3</inf> thin films and hexagonal Cu<inf>7</inf>Te<inf>4</inf> nanocrystals. The cyclic voltammetry of heterostructured electrodes with and without In<sup>3+</sup> doping both showed Faradic pseudo-capacitance behavior based on the oxidation and reduction processes. The largest exchange current density of 3.43 mA/cm<sup>2</sup> was obtained for the heterojunction-structured-Bi<inf>2</inf>Te<inf>3</inf> thin films and Cu<inf>7</inf>Te<inf>4</inf> nanocrystals with In<sup>3+</sup> doping in the WO<inf>3</inf> electrode. This implies more favorable hydrogen evolution reaction kinetics and higher electrocatalytic activity at the anode. The highest specific capacity of 90.2 mA h/g was obtained at a scan rate of 10 mV/s, with the power density reaching 1.7 kW/kg at the highest energy density value of 18.85 Wh/kg for the In<sup>3+</sup>-doped electrode. The overall results revealed the inherent properties of the new electrode materials, as well as their potential use in energy storage devices or in future electrochemical energy conversion and storage applications involving hydrogen (or oxygen) evolution reactions.
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    Structural, optical and electrochemical performances of undoped and Sn2+-doped Bi2Te3 nanoparticles on WO3 electrodes
    (2020-01-01)
    Buddeesao, Mirantee
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    Raknual, Duanghatai
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    Tubtimtae, Auttasit
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    Vailikhit, Veeramol
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    Teesetsopon, Pichanan
    A facile synthesis approach was used to prepare Sn<sup>2+</sup>-doped Bi<inf>2</inf>Te<inf>3</inf> nanospheres on a WO<inf>3</inf> electrode, and the pseudo-capacitive property was measured for samples prepared with optimum parameters. SEM micrographs revealed that after the Sn<sup>2+</sup> doping, the morphology of Bi<inf>2</inf>Te<inf>3</inf> changed from aggregated or network-like nanoparticles to smaller nanospheres with a homogeneous distribution. The X-ray diffraction pattern showed rhombohedral Bi<inf>2</inf>Te<inf>3</inf> coated on the WO<inf>3</inf> electrode. Due to the more abundant electro-active sites and charge carriers that diffused through the electrolyte to the working electrode, the Sn<sup>2+</sup>-doped Bi<inf>2</inf>Te<inf>3</inf> electrode displayed the highest specific capacity of 41.4 mAh/g at a scan rate 10 mV/s, a power density of 0.63 kW/kg, an energy density of 24.5 Wh/kg, and an LSV breakdown potential of 0.26 V. These materials may be applied in potential pseudo-capacitors and in further energy storage devices.
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    Effect of low thermal treatment temperatures on the morphological, optical and electrical properties of Sn1-xMnxTe nanocomposite films incorporated with indium cations
    (2019-12-01)
    Rukcharoen, Nuengruethai
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    Tubtimtae, Auttasit
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    Vailikhit, Veeramol
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    Teesetsopon, Pichanan
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    Kitisripanya, Nareerat
    Amorphous chalcogenide semiconductors have advantageous optical and electrochemical properties, but the influence of the thermal treatment temperature on these properties is not clearly understood. In this study, In<sup>3+</sup>-incorporated Sn<inf>1-x</inf>Mn<inf>x</inf>Te nanocomposite films were prepared on commercial glass substrates using a solution-based doctor-blading method and low thermal treatment temperatures. The effect of the thermal treatment temperature (50–200 °C) on the optical and electrical properties of the nanocomposite films was investigated. X-ray diffraction results confirmed that an amorphous nanocomposite film was formed at each thermal treatment temperature. However, variation in the optical parameters and electrical performance of the nanocomposite films with the thermal treatment temperature indicated that this temperature should not exceed 150 °C. Optimization of the thermal treatment temperature improved the light-harvesting ability of the nanocomposite films and enhanced the polarization of the incident radiation. These phenomena were caused by an increase in atomic oscillations associated with higher dipole moments in the films. The nanocomposite films subjected to thermal treatment at temperatures below 150 °C also exhibited the highest electrical conductivity. These results will allow the synthesis of improved materials for applications in solar selective surfaces and electro-optical, photovoltaic-thermal, and sensor devices.
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    Structural and electrochemical studies of undoped and In3+-doped co-binary Cu2-xTe and Bi2Te3 thin films for aqueous Na–S batteries
    (2019-10-01)
    Sreerung, Rawita
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    Raknual, Duanghatai
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    Vailikhit, Veeramol
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    Teesetsopon, Pichanan
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    Kitisripanya, Nareerat
    WO<inf>3</inf> electrodes coated with co-binary Cu<inf>2-x</inf>Te and Bi<inf>2</inf>Te<inf>3</inf> thin films were fabricated for sodium-sulfur (Na–S) batteries. Film fabrication was controlled by adjusting the pH of the solution and the indium doping concentration. The phases of orthorhombic CuTe and hexagonal Cu<inf>2</inf>Te with rhombohedral Bi<inf>2</inf>Te<inf>3</inf> were formed on the WO<inf>3</inf> electrode. After In<sup>3+</sup> doping, In<sup>3+</sup> ions act as Frenkel defects in the Cu<inf>2-x</inf>Te structure. This indicated that In<sup>3+</sup> ions are located at interstitial sites in the Cu<inf>2-x</inf>Te structure with higher defect creation energy. Furthermore, more interconnected-like nanoparticles and reduced porosity were observed, thereby indicating that indium segregation with grain boundaries presented and contributed to an enhancement of the surface mobility, nucleation density, and a smoother surface. For electrochemical characteristics, a polysulfide solution was used as a redox electrolyte for ion transport. Optimization of the pH and indium concentration attributed to improve the exchange current density (J<inf>0</inf>) and time responses for the colored and bleached states because of faster movement of Na<sup>+</sup> and S<sup>2−</sup> ions during inter/de-intercalation. Furthermore, optimization of the electrode by adjusting the pH and doping with indium is advantageous for both Na–S and rechargeable batteries because of long life cycle, reasonably high power and energy density of 306 W/kg and 9.35 Wh/kg, respectively. The highest specific capacity (C<inf>s</inf>) values of the charge and discharge cycles for In<sup>3+</sup>-doped electrodes are ∼ 21 and 19 mAh/g, respectively with the coulombic efficiency approximates 100% (average value of ∼96%). This approach may provide a general path for the fabrication of undoped and In<sup>3+</sup>-doped co-binary Cu<inf>2-x</inf>Te and Bi<inf>2</inf>Te<inf>3</inf> films on WO<inf>3</inf> electrodes and may increase our knowledge regarding Na–S batteries for further performance improvement.
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    Copper incorporation in Mn2+-doped Sn2S3 nanocrystals and the resultant structural, optical, and electrochemical characteristics
    (2018-08-15)
    Noppakuadrittidej, Prae
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    Vailikhit, Veeramol
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    Teesetsopon, Pichanan
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    Choopun, Supab
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    Tubtimtae, Auttasit
    Sn<inf>2</inf>S<inf>3</inf> nanocrystals (NCs) with both Mn<sup>2+</sup> doping and Cu<sup>2+</sup> incorporation were synthesized using a chemical bath deposition method. The Cu<sup>2+</sup> ions formed an anorthic Mn<sup>2+</sup>-doped Cu<inf>2</inf>SnS<inf>3</inf> structure with E<inf>g</inf> = 1.44 eV, which altered the material's optical and photo/electrochemical properties. After coating the bare Nb<inf>2</inf>O<inf>5</inf> electrode with Mn<sup>2+</sup>-doped Sn<inf>2</inf>S<inf>3</inf> or Mn<sup>2+</sup>-doped Cu<inf>2</inf>SnS<inf>3</inf> NCs, the photoluminescence spectrum was blue-shifted to 411.13 nm from 411.69 nm. Compared to the sample without Cu<sup>2+</sup>, the Cu<sup>2+</sup>-incorporated sample showed a slightly stronger emission at the same position, possibly due to disorder in the crystalline structure based on variations at the interface of Mn<sup>2+</sup>-doped Cu<inf>2</inf>SnS<inf>3</inf> NCs. Electrochemical analysis showed a lower charge transfer resistance in the Mn<sup>2+</sup>-doped Cu<inf>2</inf>SnS<inf>3</inf>, which is related to its larger electroactive surface area. The larger electroactive surface area is attributed to the Faradaic redox processes at the electrode surface, which suppresses the carrier recombination. The coexistence of Cu<sup>2+</sup> and Mn<sup>2+</sup> ions shortened the electron transport pathway at the interface and improved the carrier diffusion coefficient and diffusion length, leading to a higher specific capacitance that implies higher energy storage performance. Finally, the I-V characteristics of the Mn<sup>2+</sup>-doped Cu<inf>2</inf>SnS<inf>3</inf>-coated Nb<inf>2</inf>O<inf>5</inf> electrode under various light illumination conditions indicated its better efficiency in photoresponse, electron generation, and charge collection, owing to a superior charge transport mechanism. Detailed results were obtained about the charge dynamics in the as-prepared photo/electrochemical devices with Cu<sup>2+</sup> incorporation in the Mn<sup>2+</sup>-doped SnS<inf>3</inf> electrode.
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    Effect of annealing process on the properties of undoped and manganese2+-doped co-binary copper telluride and tin telluride thin films
    (2018-04-15)
    Kladkaew, Meaunfun
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    Samranlertrit, Norasate
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    Vailikhit, Veeramol
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    Teesetsopon, Pichanan
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    Tubtimtae, Auttasit
    The binary semiconductor materials Cu<inf>1.81</inf>Te and SnTe materials, without and with manganese (Mn<sup>2+</sup>) doping, were prepared by dropping a Cu-Sn-Te solution on a commercial glass substrate to fabricate a co-binary thin film. The characteristics, optical, and electrical properties of undoped and Mn<sup>2+</sup>-doped Cu<inf>1.81</inf>Te/SnTe thin films were investigated with variations in the annealing process. The XRD results confirmed the films consisted of the co-binary orthorhombic phase materials Cu<inf>1.81</inf>Te and SnTe, and that for all annealing temperatures from 50 to 400 °C an amorphous structure became prevalent in the Mn<sup>2+</sup>-incorporated co-binary thin films. The optical parameters and electrical performance varied with the annealing temperatures and Mn<sup>2+</sup> doping, showing alterations in the properties of the co-binary film. These co-binary thin films have feasibility for real applications in surface analysis, electro-optical materials, solar selective surfaces, and photovoltaic thermal devices.
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    Effective properties of undoped and Indium3+-doped tin manganese telluride (Sn1 − xMnxTe) nanoparticles via using a chemical bath deposition route
    (2017-06-09)
    Boon-on, Patsorn
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    Tubtimtae, Auttasit
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    Vailikhit, Veeramol
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    Teesetsopon, Pichanan
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    Choopun, Supab
    Tin manganese telluride nanoparticles (Sn<inf>1−x</inf>Mn<inf>x</inf>Te NPs) were first synthesized on a niobium pentoxide (Nb<inf>2</inf>O<inf>5</inf>) film using a chemical bath deposition (CBD) route. An individual particle size before and after indium (In<sup>3+</sup>) doping of ∼70–150 nm was investigated with stoichiometric formation of the SnMnTe phase. Furthermore, a cubic or rocksalt structure of the Sn<inf>0.938</inf>Mn<inf>0.062</inf>Te phase was also kept incorporated in the structure. The plotted energy band gaps for undoped and In<sup>3+</sup>-doped samples were 2.17 and 1.83 eV, respectively. The reduction of photoluminescence (PL) spectra after In<sup>3+</sup> doping, while the indium dopant acted as a trap state incorporated in Sn<inf>1−x</inf>Mn<inf>x</inf>Te NPs, showed enhanced charge separation and reduced charge recombination, which resulted in a higher charge density trapped in the conduction band of Nb<inf>2</inf>O<inf>5</inf> and was also confirmed by the result of anodic peaks in the cyclic voltammetry. These results suggest new possibilities in optoelectronic and electrochemical devices.
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    Effective performance for undoped and boron-doped double-layered nanoparticles-copper telluride and manganese telluride on tungsten oxide photoelectrodes for solar cell devices
    (2016-11-01)
    Srathongluan, Pornpimol
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    Vailikhit, Veeramol
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    Teesetsopon, Pichanan
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    Choopun, Supab
    ;
    Tubtimtae, Auttasit
    This work demonstrates the synthesis of a novel double-layered Cu<inf>2−x</inf>Te/MnTe structure on a WO<inf>3</inf> photoelectrode as a solar absorber for photovoltaic devices. Each material absorber is synthesized using a successive ionic layer adsorption and reaction (SILAR) method. The synthesized individual particle sizes are Cu<inf>2−x</inf>Te(17) ∼5–10 nm and MnTe(3) ∼2 nm, whereas, the aggregated particle sizes of undoped and boron-doped Cu<inf>2−x</inf>Te(17)/MnTe(11) are ∼50 and 150 nm, respectively. The larger size after doping is due to the interconnecting of nanoparticles as a network-like structure. A new alignment of the energy band is constructed after boron/MnTe(11) is coated on boron/Cu<inf>2−x</inf>Te nanoparticles (NPs), leading to a narrower E<inf>g</inf> equal to 0.58 eV. Then, the valence band maximum (VBM) and conduction band minimum (CBM) with a trap state are also up-shifted to near the CBM of WO<inf>3</inf>, leading to the shift of a Fermi level for ease of electron injection. The best efficiency of 1.41% was yielded for the WO<inf>3</inf>/boron-doped [Cu<inf>2−x</inf>Te(17)/MnTe(11)] structure with a photocurrent density (J<inf>sc</inf>) = 16.43 mA/cm<sup>2</sup>, an open-circuit voltage (V<inf>oc</inf>) = 0.305 V and a fill factor (FF) = 28.1%. This work demonstrates the feasibility of this double-layered structure with doping material as a solar absorber material.