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Author: search.filters.author.Kitisripanya, NareeratSubject: search.filters.subject.Indium doping

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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
    ;
    Simalaotao, Kodchakorn
    ;
    Reunchan, Pakpoom
    ;
    Vailikhit, Veeramol
    ;
    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 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
    ;
    Raknual, Duanghatai
    ;
    Vailikhit, Veeramol
    ;
    Teesetsopon, Pichanan
    ;
    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.