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Synthesis of ZIF-8 powders and their electrochemical role as a protective layer minimizing dendrite formation and elevating anode stability in Zn-ion batteries
(2025-12-01)
Chananil, Patompong
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Triosod, Sureerat
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Phumuen, Phatcharin
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Chanlek, Narong
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Kumnorkaew, Pisist
A Zn-based metal-organic framework (Zn-MOF) was synthesized via a solvothermal process using Zn(NO<inf>3</inf>)<inf>2</inf>·6H<inf>2</inf>O and 2-methylimidazole (2-Hmim) in ethanol at 120 °C for 24 h, yielding a crystalline structure consistent with ZIF-8, exhibiting a high surface area (1820.73 m2 g−1) and a large pore size (1.47 nm). The ZIF-8 powder was coated onto a Zn plate (ZIF-8@Zn) and evaluated as a Zn-ion battery anode, demonstrating significantly enhanced cycling stability, with a lifespan up to 200 h across all current densities, outperforming bare Zn (132, 49, 34, 36, and 20 h for 1–5 mA cm−2) in a 2 M ZnSO<inf>4</inf> electrolyte. Post-plating/stripping analysis revealed that ZIF-8@Zn maintained a smooth morphology, whereas bare Zn exhibited pronounced roughness and dendrite formation. Cross-sectional SEM images confirmed a swollen ZIF-8 layer with reduced Zn thickness at higher plating/stripping current densities, and XRD analysis detected Zn<inf>4</inf>SO<inf>4</inf>(OH)<inf>6</inf>·4H<inf>2</inf>O and Zn<inf>4</inf>SO<inf>4</inf>(OH)<inf>6</inf>·5H<inf>2</inf>O byproducts on both electrodes. The ZIF-8@Zn| |V<inf>2</inf>O<inf>5</inf> full-cell exhibited superior capacity (314.03 vs. 251.75 mAh g−1 at 100 mA g−1) and long-term stability, with a 22.71 % capacity increase after 1000 cycles, in contrast to an 11.52 % reduction in the Zn| |V<inf>2</inf>O<inf>5</inf> cell, highlighting ZIF-8@Zn's potential for stable Zn-ion batteries.
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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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Characterization and electrochemical properties of CuO–Cu2O@rGO nanocomposite synthesized by a seed-mediated growth process
(2022-04-01)
Wongjom, Poramed
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Tuichai, Wattana
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Karaphun, Attaphol
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Phrompet, Chaiwat
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Daengsakul, Sujittra
A CuO–Cu<inf>2</inf>O@rGO nanocomposite (CuO–Cu<inf>2</inf>O@rGO NCP) has been successfully prepared through a seed-mediated growth process. X-ray diffraction (XRD) analysis results indicated a monoclinic phase of CuO–Cu<inf>2</inf>O@rGO NCP with space group C2/c. Transmission electron microscopy (TEM) revealed agglomeration of the CuO and Cu<inf>2</inf>O nanoparticles in the rGO sheet matrix. The interaction of CuO–Cu<inf>2</inf>O@rGO NPC resulted from the aggregation and overlapping of CuO and Cu<inf>2</inf>O nanoparticles owing to the influence of a seed-mediated growth process. The electrochemical properties of the CuO–Cu<inf>2</inf>O@rGO NPC electrode indicate the storage of energy at the surface through a pseudo-capacitive mechanism. The specific capacitance at a current density of 0.5 A g−1 and the average percentage capacity retention after 1000 cycles of a CuO–Cu<inf>2</inf>O@rGO electrode at a current density of 10 A g−1 were evaluated as 125.54 F g−1 and 89.87 ± 3.30%, respectively. In the CuO–Cu<inf>2</inf>O@rGO electrode, the incorporated rGO affects the electrical conductivity and the synergistic interactions in charge–discharge processes. Interestingly, these results showed that the material was synthesized through a seed-mediated growth process and reveal the key factors that determine the combination and volume expansion of the reversible redox transition between Cu+ and Cu2+ during charge–discharge processes.
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The effect of phase transition of crednerite/delafossite CuMn1−xCrxO2 on optical, thermal, and power factor properties
(2022-03-01)
Srepusharawoot, Pornjuk
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Kosalwat, Wattana
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Ruttanapun, Chesta
This study aims to investigate the effect of the phase transition of CuMn<inf>1−</inf><inf>x</inf>Cr<inf>x</inf>O<inf>2</inf> compound on the Jahn–Teller effect which in turn affects the optical, thermal, and thermoelectric power factor properties. The CuMn<inf>1−</inf><inf>x</inf>Cr<inf>x</inf>O<inf>2</inf> samples were synthesized by a solid-state reaction method. The ab initio computation was applied to evaluate the electronic and optical properties in order to confirm the experiment data. The appearance of the phase transition from crednerite CuMnO<inf>2</inf> to delafossite CuCrO<inf>2</inf> was confirmed by X-ray diffraction (XRD) and the ab initio computation through displaying the mixed crednerite/delafossite phase; and, the existence of the Jahn–Teller effect was confirmed by the X-ray photoelectron spectroscopy (XPS) technique exhibiting the occurrence of mixed-state Mn3+/Mn4+ ions. The results obtained from XRD, XPS, and the ab initio computation implied the decrease of the Jahn–Teller behavior with increased x content under the influence of the phase transition from the crednerite phase to the delafossite phase of CuMn<inf>1−</inf><inf>x</inf>Cr<inf>x</inf>O<inf>2</inf>. Surprisingly, the Jahn–Teller distortion reduction caused an increase in the energy gap of the optical property, electrical resistivity, and activation energy in thermally activated band conduction. The effect suffered the specific heat behavior by being separated into two groups of crednerite and delafossite, and enhanced the small polaron behavior by increasing the activation energy of thermally activated band conduction. The phase transition reduced the results of thermal conductivity, thermopower, and thermoelectric power factor properties. In other words, the effect of the phase transition from the crednerite CuMnO<inf>2</inf> phase to the delafossite CuCrO<inf>2</inf> phase on CuMn<inf>1−</inf><inf>x</inf>Cr<inf>x</inf>O<inf>2</inf> compound reduced the Jahn–Teller effect with increased Cr content which in turn caused changes in the optical, thermal, and thermoelectric power factor properties. The effect of the phase transition is advantageous for the improvement of material properties.
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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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Electrochemical mechanisms of activated carbon, α-MnO2 and composited activated carbon-α-MnO2 films in supercapacitor applications
(2021-12-30)
Tagsin, Patin
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Suksangrat, Pitphichaya
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Klangtakai, Pawinee
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Srepusharawoot, Pornjuk
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Ruttanapun, Chesta
Pure α-MnO<inf>2</inf> and activated carbon-MnO<inf>2</inf> (AC-MnO<inf>2</inf>) films coated on Ni foam by electrophoretic deposition were applied as a supercapacitor electrode. The specific capacitance of AC-MnO<inf>2</inf> films (155.03 F g−1) surpasses those of the pure AC (110.62 F g−1) and pure MnO<inf>2</inf> film in the 1 M NaOH electrolyte. EDX and XPS detect an increase in the Na content and the reduction of Mn4+ to Mn3+ on the discharged MnO<inf>2</inf> electrode (at 0.0 V), whereas a decrease in the Na content and the oxidation of Mn3+ to Mn4+ were obtained on the charged MnO<inf>2</inf> electrode (at 0.45 V). Computational simulation of the Na inserted α-MnO<inf>2</inf> structure displays the connection of Na to O atoms and the increasing electron density on Mn atoms. EDX of the charged AC-MnO<inf>2</inf> (at −1.0 V) film detects a rise in the Na and a fall in the O contents, but the discharged AC-MnO<inf>2</inf> film (at 0.0 V) shows a decrease in Na and increase in O contents. The AC-MnO<inf>2</inf> film could retain 82.29% of the initial specific capacity after 10,000 cycles. Four series-supercapacitor coin cell assembled from the AC-MnO<inf>2</inf> anode and MnO<inf>2</inf> cathode delivers a power density of 2.79 kW kg−1 and an energy density of 168.8 Wh kg−1.
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Effect of free oxygen radical anions and free electrons in a Ca12Al14O33 cement structure on its optical, electronic and antibacterial properties
(2019-05-01)
Phrompet, Chaiwat
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Sriwong, Chaval
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Srepusharawoot, Pornjuk
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Maensiri, Santi
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Chindaprasirt, Prinya
The aim of this work was to investigate the effect of free oxygen radicals and free electrons in a Ca<inf>12</inf>Al<inf>14</inf>O<inf>33</inf> (C12A7) cement structure on the optical, electronic and antibacterial activity of this material. Ca<inf>12</inf>Al<inf>14</inf>O<inf>33</inf> was successfully fabricated via rapid heating to high temperatures by high frequency electromagnetic induction. Ca<inf>12</inf>Al<inf>14</inf>O<inf>33</inf> cement samples were characterized using XRD and UV-Vis-DRS spectroscopy. The morphology and chemical composition of the samples were also investigated using SEM and EDS techniques. The presence of free oxygen radicals (O<inf>2</inf> −ions) in the insulating structure of Ca<inf>12</inf>Al<inf>14</inf>O<inf>33</inf> was confirmed using Raman spectroscopy showing a spectrum peak at 1067 cm−1. The excitation of free electrons in the Ca<inf>12</inf>Al<inf>14</inf>O<inf>33</inf> cement was indicated by UV-Vis absorption spectra at 2.8 eV and an optical energy gap of 3.5 eV, which is consistent with the first-principles calculations for the band energy level. The effects of free oxygen radicals and free electrons in the Ca<inf>12</inf>Al<inf>14</inf>O<inf>33</inf> structure as antibacterial agents against Escherichia Coli (E. coli) and Staphylococcus Aureus (S. aureus) were investigated using an agar disk-diffusion method. The presence of O<inf>2</inf> − anions as a reactive oxygen species (ROS) at the surface of Ca<inf>12</inf>Al<inf>14</inf>O<inf>33</inf> caused inhibition of E. coli and S. aureus cells. The free electrons in the conducting C12A7 reacted with O<inf>2</inf> gas to produce ROS, specifically super oxides (O<inf>2</inf> −), superoxide radicals (O<inf>2</inf> •-), hydroxyl radicals (OH•) and hydrogen peroxide (H<inf>2</inf>O<inf>2</inf>), which exhibited antibacterial properties. Both mechanisms were active against bacteria without effects from nano-particle sized materials and photocatalytic activity. The experimental results showed that the production of ROS from free electrons was greater than that of the free O<inf>2</inf> − anions in the structure of Ca<inf>12</inf>Al<inf>14</inf>O<inf>33</inf>. The antibacterial actions for insulating and conducting Ca<inf>12</inf>Al<inf>14</inf>O<inf>33</inf> were different for E. coli and S. aureus. Thus, Ca<inf>12</inf>Al<inf>14</inf>O<inf>33</inf> cement has antibacterial properties that do not require the presence of nano-particle sizes materials or photocatalysis.
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Effect of Fe3+-doped Ca12Al14O33 cement on optical and thermal properties
(2018-02-01)
Ruttanapun, Chesta
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Srepusharawoot, Pornjuk
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Maensiri, Santi
This study aims to investigate the effect Fe ions doped into Ca<inf>12</inf>Al<inf>14</inf>O<inf>33</inf> (C12A7, 12CaO-7Al<inf>2</inf>O<inf>3</inf>) cement compound on its thermal and optical properties. Polycrystalline samples of Ca<inf>12</inf>Al<inf>14−x</inf>Fe<inf>x</inf>O<inf>33</inf> (where x = 0.0, 0.5, and 1.0) were prepared via a solid state reaction in an oxygen atmosphere. The lattice constant of Ca<inf>12</inf>Al<inf>14</inf>O<inf>33</inf> determined using an XRD technique was in excellent agreement with first-principles calculations. With increasing Fe concentrations, the lattice constants were found to have increased. Additionally, the optical gaps of Ca<inf>12</inf>Al<inf>14−x</inf>Fe<inf>x</inf>O<inf>33</inf>, (x = 0, 0.25, 0.5, and 1.0) were 3.9 eV, 3.77 eV, 3.75 eV and 3.63 eV, respectively. It was clearly seen that the optical gap decreased with increasing Fe concentrations. As revealing by first-principles calculations, the optical gap was directly related to the electronic transition from the occupied electronic state of extra-framework O2− ions (as free O2− ions inside nano-cage) to the conduction band. Moreover, we also found that the thermal conductivity Ca<inf>12</inf>Al<inf>14−x</inf>Fe<inf>x</inf>O<inf>33</inf> was reduced when the larger atomic mass and atomic radii Fe was substituted into Al sites. Hence, this indicated that Fe3+-substitution into Al3+ sites of Ca<inf>12</inf>Al<inf>14</inf>O<inf>33</inf> cement directly affected both its optical gap and thermal conductivity.

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