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Hydrothermal transforming phase structure and chemical composition of V2O5 for elevating electrochemical property of zinc ion batteries
(2024-05-01)
Triosod, Sureerat
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Phakkhawan, Authit
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Phumuen, Phatcharin
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Wanabut, Wassana
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Chanlek, Narong
V<inf>2</inf>O<inf>5</inf> was hydrothermally modified in NaOH or KOH solutions at 180 °C for 24 h. The NaOH-modified powders had a nanorod-like structure with a crystal structure matching Na<inf>2</inf>V<inf>6</inf>O<inf>16</inf>·nH<inf>2</inf>O. The TG/DTA results of Na<inf>2</inf>V<inf>6</inf>O<inf>16</inf>·nH<inf>2</inf>O powders show a mass reduction of 4.24 % at 300 °C, corresponding to n of 1.496. KOH-modified powders have large rods and irregular structures with a crystal structure matching KV<inf>3</inf>O<inf>8</inf>. Its TG/DTA spectrum shows a very small percentage change, just 0.37 % at 600 °C. Cyclic voltammetry (CV) curves of a Na<inf>2</inf>V<inf>6</inf>O<inf>16</inf>·nH<inf>2</inf>O cathode in a 2 M ZnSO<inf>4</inf> electrolyte exhibit higher oxidation and reduction current densities than those of pure V<inf>2</inf>O<inf>5</inf> and KV<inf>3</inf>O<inf>8</inf> electrodes.The best capacity of a Na<inf>2</inf>V<inf>6</inf>O<inf>16</inf>·nH<inf>2</inf>O electrode is 296.10 mAh g-1 at a current density of 50 mA g−1, which is higher than those of pure V<inf>2</inf>O<inf>5</inf> (102.90 mAh g-1) and KV<inf>3</inf>O<inf>8</inf> (91.07 mAh g-1) electrodes. EDS and XPS results reveal that the charge and discharge states involve de-insertion and insertion of Zn2+ ions out of/into the electrodes. Computational analysis of Zn intercalation into V<inf>2</inf>O<inf>5</inf>, Na<inf>2</inf>V<inf>6</inf>O<inf>16</inf>·nH<inf>2</inf>O, and KV<inf>3</inf>O<inf>8</inf> structures displays increasing electron density on neighboring V atoms, which explains the increasing V4+/V5+ ratio in the discharged state as evidenced by XPS spectra.
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Effect of GeI2 and GeBr2 incorporation on perovskite properties and performance of carbon-based perovskite solar cells
(2023-04-01)
Aunping, Namfon
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Kumlangwan, Pantiwa
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Towannang, Madsakorn
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Chanlek, Narong
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Kumnorkaew, Pisist
CH<inf>3</inf>NH<inf>3</inf>PbI<inf>3</inf> (MAPbI<inf>3</inf>) film was prepared by a convective method, and its X-ray diffraction spectrum displays the tetragonal perovskite structure. GeI<inf>2</inf> and GeBr<inf>2</inf> powders dissolve poorly in a mixed dimethylformamide-dimethylsulfoxide (DMF-DMSO) solvent, but the introduction of 5 wt% 5-ammonium valeric acid iodide (5-AVAI) into the mixed DMF-DMSO solvent greatly promotes GeI<inf>2</inf> and GeBr<inf>2</inf> solubility. XRD spectra of the (5-AVAI)MAPbI<inf>3</inf>, MAGe<inf>x</inf>Pb<inf>1–x</inf>I<inf>3</inf>, and MAGe<inf>x</inf>Pb<inf>1–x</inf>Br<inf>2x</inf>I<inf>3–2x</inf> (x = 0.0625 and 0.125) films exhibit a tetragonal perovskite structure, but the film morphologies become rougher than that of the pristine MAPbI<inf>3</inf> film. Discontinuous islands are formed on MAGe<inf>x</inf>Pb<inf>1–x</inf>I<inf>3</inf> and MAGe<inf>x</inf>Pb<inf>1–x</inf>Br<inf>2x</inf>I<inf>3–2x</inf> (x = 0.125) films. X-ray photoemission spectroscopy (XPS) analysis detected the Ge element on all Ge-doped films. The best performance levels of the carbon-based hole transport layer-free MAGe<inf>x</inf>Pb<inf>1–x</inf>I<inf>3–x</inf> (x = 0.0625, η= 3.63%) and MAGe<inf>x</inf>Pb<inf>1–x</inf>Br<inf>2x</inf>I<inf>3–2x</inf> (x = 0.0625, η = 2.95%) perovskite solar cells are lower than that of the pristine MAPbI<inf>3</inf>–based perovskite solar cell (η = 5.28%). This is likely due to the increased surface roughness, pin-holes, isolated islands, and the decreased light absorbance of the Ge-doped films in comparison with the pristine MAPbI<inf>3</inf> film.
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Influence of SCN− moiety on CH3NH3PbI3 perovskite film properties and the performance of carbon-based hole-transport-layer-free perovskite solar cells
(2022-01-01)
Prasan, Primprapha
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Aunping, Namfon
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Chanlek, Narong
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Kumlangwan, Pantiwa
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Towannang, Madsakorn
CH<inf>3</inf>NH<inf>3</inf>PbI<inf>3</inf> perovskite films were prepared via a hot-casting method using six different CH<inf>3</inf>NH<inf>3</inf>I, PbI<inf>2</inf> and Pb(SCN)<inf>2</inf> solutions. Surface morphology of perovskite films with low SCN− dopant levels (0.0625 M and 0.125 M Pb(SCN)<inf>2</inf>) showed smooth surfaces and large grain sizes. However, with the high SCN− dopant levels (0.1875 M and 0.25 M Pb(SCN)<inf>2</inf>), rough surfaces were produced with pinholes. The crystal of pure CH<inf>3</inf>NH<inf>3</inf>PbI<inf>3</inf> (0 M Pb(SCN)<inf>2</inf>) film is a tetragonal perovskite structure. XRD spectra of all five Pb(SCN)<inf>2</inf> added films show the present of CH<inf>3</inf>NH<inf>3</inf>PbI<inf>3</inf> films and the additional peak at 12.66°. Rietveld refinement analysis reveals that the Pb(SCN)<inf>2</inf> addition causes the second phase PbI<inf>2</inf> formation along with the tetragonal MAPbI<inf>3</inf> perovskite film rather than the CH<inf>3</inf>NH<inf>3</inf>Pb(SCN)<inf>x</inf>I<inf>3-x</inf> perovskite formation. The carbon-based hole-transport-layer (HTL)-free perovskite (from 0.0625 M Pb(SCN)<inf>2</inf> dopant) solar cell is the optimal ratio in generating a promising cell efficiency, 6.34%, with a good efficiency retention of 79.43% after 30 days of testing in comparison to a pure CH<inf>3</inf>NH<inf>3</inf>PbI<inf>3</inf> (0 M Pb(SCN)<inf>2</inf> dopant) perovskite solar cell with an efficiency retention of only 26.92%. The great stability of the Pb(SCN)<inf>2</inf> added perovskite solar cells is attributed to the PbI<inf>2</inf> layer covered MAPbI<inf>3</inf> grains blocking oxygen and/or water molecules from degrading MAPbI<inf>3</inf> perovskite.
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A Flexible plastic-stainless steel dye-sensitized solar cell based on organic T-/T2 electrolyte
(2014-03-25)
Pimanpang, Samuk
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Towannang, Madsakorn
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Thiangkaew, Anongnad
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Maiaugree, Wasan
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Uppachai, Pikaned
SUMMARY: Flexible dye-sensitized solar cells (DSSCs) were fabricated using a TiO<inf>2</inf> film coated on stainless steel (TiO<inf>2</inf>/SS) as the working electrode and a Pt film coated on conductive plastic (Pt/plastic) as the counter electrode. Thin Pt film was deposited on conductive plastic specimens for four different deposition times (30, 60, 90 and 120s) using an electrochemical deposition process. Scanning electron micrographs of the resulting Pt films showed that Pt nanoparticles formed on conductive plastic. The DSSC characteristics were analyzed by illuminating light on the counter electrode. The performance of the cell with 30s of Pt deposition (30s-Pt) showed the highest DSSC efficiency, ~2.72%. Cell efficiency decreased with the duration of Pt deposition (or Pt thickness). This is attributed to the reduced transmittance through the thicker Pt films, which is supported by UV-visible spectroscopic measurements. © 2013 John Wiley & Sons, Ltd.
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Supercapacitor based on multi-walled carbon nanotubes/carbon black composites-coated wooden sheet
(2014-01-01)
Dulyaseree, Paweena
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Jarernboon, Wirat
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Wongwiriyapan, Winadda
Supercapacitor consists of two carbon electrodes and wooden sheet as a separator. Three types of carbon electrodes were prepared; carbon black (CB), multi-walled carbon nanotubes (MWNTs) and composites of MWNTs and CB (MWNTs-CB). Electrode pastes were coated on both sides of wooden sheet. The thickness of wooden sheet was varies from 1 mm to 5 mm. The morphology of CB, MWNTs and MWNTs-CB were characterized by scanning electron microscopy (SEM). The supercapacitor performance was characterized by cyclic voltammetry and galvanostatic charge/discharge techniques. Among carbon electrode materials, MWNTs-CB shows the highest specific capacitance. The high specific capacitance of MWNTs-CB may be due to the high surface area of MWNTs incorporated with CB acting as spacer for MWNTs agglomeration protection and electrolyteelectrode accessibility improvement. Moreover, wooden sheet with a thickness of 2 mm shows the highest specific capacitance.
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Modification of working electrode of dye-sensitized solar cell using TiO2 nanopraticles/TiO2 nanofibers/CNT composite
(2013-10-29)
Mekprasart, Wanichaya
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Jarernboon, Wirat
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Techitdheera, Wicharn
The working electrode of dye-sensitized solar cell was modified using composite material of TiO<inf>2</inf> particles/TiO<inf>2</inf> nanofibers/CNT by doctor blade method. Structural properties of pre-cursor materials and as-prepared working electrodes were well characterized by X-ray diffraction and scanning electron microscopy. The efficiency and relevant parameters of solar cells with modified electrodes were measured. The optimized weight ratios of 1 wt.% TiO<inf>2</inf> nanofibers derived from leucoxene and 0.01 wt.% CNT exhibited the highest improvement of DSSC efficiency with solar efficiency of 1.11% and fill factor of 0.32. The increase of current density may be originated from easier electron transfer that occurred in the device with modified TiO<inf>2</inf> particles/TiO<inf>2</inf> nanofibers/CNT composite. © (2013) Trans Tech Publications, Switzerland.
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Chemically deposited polypyrrole-nanoparticle counter electrode for inorganic I -/I 3 - and organic T -/T 2 dye-sensitized solar cells
(2012-12-01)
Towannang, Madsakorn
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Pimanpang, Samuk
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Thiangkaew, Anongnad
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Rutphonsan, Phikun
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Maiaugree, Wasan
Pure polypyrrole (PPy) and composited PPy-nanoparticles (multiwall carbon nanotubes (MWCNTs), nickel (Ni) or, titanium dioxide (TiO <inf>2</inf>)) films were coated on conductive glass by a chemical deposition method. They were used as dye-sensitized solar cell counter electrodes. The performance of pure PPy based dye-sensitized solar cells (DSSCs) was ∼6.00% and ∼2.81% for I -/I <inf>3</inf> - and T -/T <inf>2</inf> electrolytes, respectively. The efficiencies increased after MWCNTs and Ni nanoparticle incorporation for both electrolytes, but decreased with TiO <inf>2</inf> addition. PPy-MWCNTs DSSCs delivered the highest efficiency; ∼7.20% and ∼3.19% for I -/I <inf>3</inf> - and T -/T <inf>2</inf> electrolytes, respectively. The improvement of the energy conversion efficiency after MWCNTs and Ni incorporation is attributed to an increase in the electrode surface area and/or a reduction of charge-transfer resistance at the electrolyte/counter electrode interface. © 2012 Elsevier B.V.
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Co-electrophoretic deposition multiwall carbon nanotubes/Pt counter electrodes for dye-sensitized solar cell
(2012-10-01)
Maiaugree, Wasan
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Pimanpang, Samuk
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Towannang, Madsakorn
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Rutphonsan, Phikun
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Laupa, Seksan
Multiwall carbon nanotubes (MWCNTs) and platinum (Pt) were coated on fluorine doped tin oxide (FTO) coated glass by a direct current electrophoretic method, and were used as dye-sensitized solar cell counter electrodes. Scanning electron microscopy (SEM) detected the deposition of carbon nanotubes on FTO-glass. The deposition of Pt nanoparticles on carbon nanotube surfaces was confirmed by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Cell efficiencies of MWCNTs, Pt and MWCNTs/Pt dye-sensitized solar cells (DSSCs) were ∼1:41, ∼8:13, and ∼8:90%, respectively. The improvement of the composited MWCNTs/Pt cell efficiency is due to the presence of both catalysts (MWCNTs and Pt) enhancing counter electrode catalytic activity as observed by cyclic voltammetry (CV) and reducing charge-transfer resistance as observed by electrochemical impedance spectroscopy (EIS). © 2012 The Japan Society of Applied Physics.
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Optimization of TiO 2 nanoparticle mixed PEDOT-PSS counter electrodes for high efficiency dye sensitized solar cell
(2012-09-01)
Maiaugree, Wasan
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Pimanpang, Samuk
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Towannang, Madsakorn
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Saekow, Saman
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Jarernboon, Wirat
Poly(3,4-Ethylendioxythiophene)-Poly(Styrene Sulfonate) (PEDOT-PSS) mixed with titanium dioxide (TiO <inf>2</inf>) nanoparticles was coated on conductive glass substrate by a doctor blading method and used as dye-sensitized solar cell (DSSC) counter electrodes. The energy conversion efficiency is significantly improved after TiO <inf>2</inf> nanoparticle incorporation. This improvement is attributed to an increase in counter electrode catalytic activity and a decrease in counter electrode charge transfer resistance. These phenomena were observed using Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS), respectively. The efficiency of polymer-TiO <inf>2</inf> based DSSCs varied with the ratio of small (∼ 25 nm) to large (∼ 100 nm) TiO <inf>2</inf> nanoparticles. The highest efficiency (∼ 8.49%) was obtained with a ratio of 30% large to 70% small (wt/wt) nanoparticles inTiO <inf>2</inf> electrodes. This efficiency is superior to that of Pt DSSC (∼ 7.50%). © 2011 Elsevier B.V.
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High intensity UV radiation ozone treatment of nanocrystalline TiO 2 layers for high efficiency of dye-sensitized solar cells
(2012-09-01)
Saekow, Samarn
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Maiakgree, Wasan
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Jarernboon, Wirat
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Pimanpang, Samuk
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Amornkitbamrung, Vittaya
We have improved the conversion efficiency of dye-sensitized solar cells (DSSCs) by using high intensity UV-ozone treatment on nanocrystalline TiO <inf>2</inf> layers after sintering. The UV light sources used had powers of 1650 W and 500 W. UV-ozone treatment of nanocrystalline TiO <inf>2</inf> layers was performed for 10 min with a fixed distance between TiO <inf>2</inf> layers and UV light source of about 3 cm. Experimental results indicate that photocurrent and power conversion efficiency of cells increased when using high power 1650 W and 500 W UV-ozone treatment on TiO <inf>2</inf> layers. The short circuit current density (J <inf>sc</inf>) increased to 25.29 ± 0.23 mA/cm 2 and 22.22 ± 0.47 mA/cm 2, the open circuit voltage (V <inf>oc</inf>) to 0.73 ± 0.02 V and 0.74 ± 0.02 V, the fill factor (FF) to 0.66 ± 0.01 and 0.71 ± 0.03 and the power conversion efficiency to 11.95 ± 0.45% and 11.12 ± 0.28% respectively. The DSSCs were characterized for absorption dye, chemical structure on nanocrystalline TiO <inf>2</inf> layer and electrochemical properties by UV-visible spectroscopy, XPS, XRD, contact angle measurement and impedance spectroscopy respectively. © 2012 Elsevier B.V. All rights reserved.

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