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Dielectric and electrochemical behavior of hydrothermally synthesized Zn-doped titanate nanotubes
(2026-11-01)
Masakul, Pristanuch
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Krongkitsiri, Pacharee
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Thongbai, Prasit
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Kidkhunthod, Pinit
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Maensiri, Santi
A bstract Zn-doped titanate nanotubes (Zn-doped TNTs) with the composition of Zn<inf>x</inf>Ti<inf>3-x</inf>O<inf>7</inf>, (Na<inf>0.96</inf>H<inf>1.04</inf>∙3.42H<inf>2</inf>O) (where x = 0, 0.05, 0.1, and 0.2) were synthesized via a hydrothermal method at 130 °C for 24 h. Structural and morphological characterization using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), UV-Vis (Ultraviolet-Visible), X-ray Absorption Near Edge Structure (XANES), and Brunauer-Emmett-Teller (BET) techniques confirmed the formation of well-defined nanotubes with controlled dimensions. Transmission electron microscopy (TEM) images of undoped and Zn-doped titanate nanotubes reveal uniform hollow nanotubular structures with diameters of ∼7–15 nm and multilayered walls. The dielectric properties of the Zn-doped TNTs were examined using an LCR meter across a frequency range of 102–106 Hz. The results revealed a remarkably high dielectric constant (ε′) (∼104-105 at 30 °C and 1 kHz), which was attributed to Debye-like relaxation governed by Maxwell-Wagner polarization. The dielectric response exhibited a strong dependence on Zn doping levels, with higher Zn content leading to enhanced permittivity. Electrochemical properties were evaluated through cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). The Zn-doped TNTs demonstrated a specific capacitance ( C ) of 23 F g−1 at a scan rate of 1 mV s−1, indicating their potential for energy storage applications. This systematic investigation of Zn incorporation provides critical insights into its impact on the structural, dielectric, and electrochemical properties of titanate nanotubes (TNTs). These findings provide useful insight for further optimization of doped titanate nanostructures toward advanced multifunctional dielectric and electrochemical energy-storage applications.
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Dry-gel synthesis of Ti-beta for epoxidation of unsaturated fatty acid methyl esters (FAMEs)
(2026-09-01)
Yomthong, Krissanapat
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Saenluang, Kachaporn
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Soyphet, Asadawut
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Ittisanronnachai, Somlak
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Padchasri, Jintara
The Ti-beta was synthesized via a dry-gel conversion approach with the direct incorporation of titanium from titano-aluminosilicate nanobeads (Ti-SiAl-NB). At first, the Ti-SiAl-NB was prepared and employed as the precursor for zeolite crystallization. Powder XRD (PXRD) patterns confirm the amorphous nature of the nanobeads. These Ti-SiAl-NB precursors were subsequently converted to the Ti-beta zeolite via the dry-gel conversion approach. Structural characterization using PXRD, high-resolution TEM, and selected area electron diffraction (SAED) confirmed the formation of a beta zeolite framework, with dominant lattice planes indexed to (101) and (302). UV-vis DRS indicated that Ti existed as a tetrahedrally coordinated (TiIV) and non-framework Ti. Unfortunately, the as-synthesized Ti-beta exhibited a low catalytic activity in methyl oleate (MO) epoxidation, which is attributed to the prevalence of closed site TiIV [Ti(OSi)<inf>4</inf>] species that restrict substrate accessibility to active sites. To address this limitation, a post-synthetic treatment involving framework etching was applied to generate open site TiIV [Ti(OSi)<inf>3</inf>OH] species. As a result, MO conversion increased by approximately 2.73-fold, with epoxide selectivity up to 70%. Catalyst stability tests demonstrated sustained MO conversion of 65–72% and epoxide selectivity above 65% over several consecutive catalytic cycles. This work highlights a sustainable catalyst design strategy that combines the dry-gel conversion process with mild post-treatment to enhance active site accessibility and catalytic performance in the epoxidation of bulky molecules.
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Effect of Ba0.93Ca0.04La0.03Sn0.1Ti0.9O3 addition on structural and electrical properties of lead-free 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 piezoelectric ceramics
(2025-12-01)
Kantha, Puripat
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Unruan, Muangjai
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Tunkasiri, Tawee
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Pengpat, Kamonpan
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Sukkha, Usa
The doping of other materials into the structure of BCZT ceramics can improve the electrical properties. The lead-free piezoelectric ceramics in the (1-x)BCZT–xBCLST binary system, where x = 0.00, 0.01, 0.03, 0.05, and 0.07 mol, were synthesized using a two-step mixed oxide method. Initially, pure phases of 0.5Ba(Zr<inf>0.2</inf>Ti<inf>0.8</inf>)O<inf>3</inf>-0.5(Ba<inf>0.7</inf>Ca<inf>0.3</inf>)TiO<inf>3</inf> (BCZT) and Ba<inf>0.93</inf>Ca<inf>0.04</inf>La<inf>0.03</inf>Sn<inf>0.1</inf>Ti<inf>0.9</inf>O<inf>3</inf> (BCLST) powders were separately prepared by mixed oxide and conventional solid-state reaction methods. X-ray diffraction patterns and Ti K-edge X-ray Absorption Near-Edge Structure (XANES) spectra revealed structural distortions in BCLST-doped ceramics. The electrical properties including dielectric, piezoelectric, and ferroelectric properties were evaluated. Besides, the dielectric constant and dielectric loss at room temperature of BCZT–BCLST ceramics were enhanced with increasing BCLST content. The dielectric properties at room temperature improved with increasing BCLST concentration from x = 0.00 to x = 0.03 mol, with the maximum dielectric constant rising from 1408 to 2552—an increase of approximately 81 %. The hysteresis P–E loop of BCZT–BCLST ceramics exhibited a slim loop, with a maximum remanent polarization (P<inf>r</inf>) of 7.22 μC/cm2 observed at x = 0.03 mol. The optimal doping condition for BCLST in BCZT ceramics was found at 0.03 mol, yielding the highest piezoelectric coefficient (d<inf>33</inf>) of 235 pC/N—an improvement of approximately 9 % compared to the undoped sample (x = 0.00).
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Thermally induced phase transition and dielectric relaxation in lead-free BaTi0.94Sn0.06O3 Ceramics: Insights from in-situ XRD and XAS
(2025-11-01)
Sukkha, Usa
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Chanlek, Narong
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Kidkhunthod, Pinit
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Kolodiazhnyi, Taras
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Vittayakorn, Wanwilai
Lead-free BaTi<inf>0.94</inf>Sn<inf>0.06</inf>O<inf>3</inf> (BTS) ceramics were synthesized using the conventional solid-state reaction method to investigate thermally induced phase transitions and dielectric relaxation phenomena. A combination of in-situ X-ray Diffraction (XRD) and in-situ Synchrotron X-ray Absorption Spectroscopy (XAS) was employed to examine phase transitions across the temperature range of 200–400 K. The results reveal sequential phase transitions: rhombohedral-orthorhombic (R + O) at 200 K, orthorhombic (O) at 250–300 K, tetragonal (T) at 325–359 K, and tetragonal-cubic (T + C) at 373–400 K. Dielectric measurements highlight an anomalous relaxation behavior at 70–160 K, attributed to domain wall freezing. This phenomenon follows Vogel-Fulcher behavior, with an activation energy of 14 meV, a freezing temperature of 82 K, and an attempt frequency of 4.7 × 106 Hz. X-ray Photoelectron Spectroscopy (XPS) analysis reveals oxygen deficiency on the surface of the BTS ceramic, resulting in the coexistence of Ti3+/Ti4+ and Sn2+/Sn4+ oxidation states. These defects significantly influence the dielectric and phase transition properties. This study provides comprehensive insights into the interplay between local structural changes and phase transition mechanisms in BTS ceramics. By employing a multi-technique approach, it advances the understanding of dielectric and ferroelectric behaviors, positioning BTS ceramics as promising candidates for lead-free dielectric and ferroelectric device applications.
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Tailoring the First Coordination Shell of Isolated Ti(IV) Active Sites in Zeolite Frameworks Boosting Catalytic Activity in Epoxidation
(2025-05-08)
Klinyod, Sorasak
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Yomthong, Krissanapat
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Suttipat, Duangkamon
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Pornsetmetakul, Peerapol
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Kidkhunthod, Pinit
We present a strategy to precisely tune the local structure of the tetrahedrally coordinated titanium (Ti) sites incorporated in the zeolite framework via a one-pot hydrothermal synthesis with the aid of NH<inf>4</inf>F without any further postmodification step. This approach effectively prevents typical issues observed in postsynthetic methods, such as Ti leaching and zeolite framework degradation. By optimizing the NH<inf>4</inf>F concentration in the synthesis precursor, the formation of open Ti(OSi)<inf>3</inf>OH and Ti(OSi)<inf>3</inf>F active species can be precisely controlled. To elucidate the relationship between various Ti active species, including closed Ti(OSi)<inf>4</inf>, open Ti(OSi)<inf>3</inf>OH, and open Ti(OSi)<inf>3</inf>F sites and their catalytic performances in methyl oleate (MO) epoxidation, we employed ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS), fluorine X-ray absorption near edge structure spectroscopy (F-XANES), and density functional theory (DFT) calculations. Our findings reveal that increased positive charges on Ti active centers, in the order of closed Ti(OSi)<inf>4</inf> < open Ti(OSi)<inf>3</inf>OH < open Ti(OSi)<inf>3</inf>F, correlate with enhanced catalytic performance in MO epoxidation. However, an excessive proportion of Ti(OSi)<inf>3</inf>F species in the framework can diminish catalytic performance by promoting undesired side reactions. Therefore, we propose an optimized balance between open Ti(OSi)<inf>3</inf>OH and open Ti(OSi)<inf>3</inf>F species in the zeolite structure to maximize the catalytic activity of epoxidation.
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Multi-phase structure electrospun CNF@Ag/Mn/Bi/Fe composite nanofiber enhanced supercapacitor behavior
(2025-02-15)
Sinprachim, Tanayt
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Klompong, Narit
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Chanlek, Narong
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Kidkhunthod, Pinit
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Maensiri, Santi
This study presents the development of carbon-based multiphase metal oxide nanocomposites (CNF@MO<inf>x</inf>; M = Ag, Mn, Bi, and Fe) incorporating silver, manganese, bismuth, and iron nanoparticles within polyacrylonitrile (PAN)-derived carbon nanofibers. These nanocomposites were fabricated via the electrospinning technique with metal oxide concentrations of 10, 20, and 40 %w. This was followed by annealing in an argon atmosphere. The resulting nanofibers exhibited diameters ranging from 559 to 830 nm, with embedded nanoparticles measuring from 9 to 21 nm. Comprehensive characterization revealed that the nanofibers possessed uniform morphology, high porosity, and robust thermal stability. X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) confirmed the valence states of the metal oxides (Ag⁰, Bi³⁺, Mn²⁺, Mn³⁺, Fe²⁺, and Fe³⁺), which are integral to redox reactions and charge storage mechanisms. Among the fabricated composites, CNF@Ag/Mn/Bi/Fe-20 demonstrated the best electrochemical performance, achieving a specific capacitance of 156 F g−1 at a scan rate of 2 mV s−1 and outstanding cycling stability with a capacity retention of over 96 % after 1400 charge-discharge cycles. The synergistic combination of double-layer capacitance and pseudocapacitance mechanisms in these nanofibers represents a significant improvement over conventional electrode material. This study highlights CNF@Ag/Mn/Bi/Fe nanocomposites as highly promising candidates for advanced energy storage applications, particularly in supercapacitor technologies.
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Preface
(2025-02-01)
Yimnirun, Rattikorn
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Kidkhunthod, Pinit
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Kaewkhao, Jakrapong
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Vittayakorn, Naratip
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D'Angelo, Paola
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UV–Vis Spectroscopy for Energy Storage and Related Materials
(2025-01-01)
Ayawanna, Jiratchaya
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Chaiyaput, Salisa
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Kidkhunthod, Pinit
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Sittimart, Phongsapak
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Lakhonchai, Anthika
This chapter has provided the reader with fundamental knowledge of Ultraviolet–visible (UV–Vis) techniques as well as applications on energy storage material and the latest progress in analytical chemistry. With the introduction of the progress in UV–Vis instrument application, this chapter not only presents the opportunity to improve conventional UV–Vis techniques but also announces a bright future for the UV–Vis spectrophotometer to measure more types of samples in practical works.
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Rational Design of Isolated Tetrahedrally Coordinated Ti(IV) Sites in Zeolite Frameworks for Methyl Oleate Epoxidation
(2024-10-16)
Klinyod, Sorasak
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Yomthong, Krissanapat
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Iadrat, Ploychanok
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Kidkhunthod, Pinit
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Choojun, Kittisak
The rational design of isolated metals containing zeolites is crucial for the catalytic conversion of biomass-derived compounds. Herein, we explored the insertion behavior of the isomorphic substitution of Ti(IV) in different zeolite frameworks, including ZSM-35 (FER), ZSM-5, and BEA. The different aluminium topological densities of each zeolite framework lead to the creation of different degrees of vacant sites for hosting the tetrahedrally coordinated Ti(IV) active sites. These observations show the precise control of the degree of four-coordinated Ti(IV) sites in a zeolite framework, especially in BEA topology, by tuning the degree of unoccupied sites in the host zeolite structure via dealumination. Interestingly, the more vacancies in the host zeolite structure, the more isolated tetrahedrally coordinated Ti(IV) can be increased, eventually enhancing the catalytic performance in methyl oleate (MO) epoxidation for producing methyl-9,10-epoxystearate (EP). The engineered Ti-β exhibits outstanding performances in bulky MO epoxidation with the amount of produced EP per number of Ti sites up to 17.1±1.8 mol mol−1. This observation discloses an alternative strategy for optimizing catalyst efficiency in the rational design of the Ti-embedding zeolite catalyst, endeavoring to reach highly efficient catalytic performance.
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Glass-sulfur composite cathodes: A new strategy for improving the performance of lithium-sulfur batteries
(2024-10-01)
Siriroj, Sumeth
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Padchasri, Jintara
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Montreeuppathum, Amorntep
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Sonsupap, Somchai
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Maensiri, Santi
In this study, we investigated the potential of glass-sulfur composites to improve lithium–sulfur battery (LSB) performance. Glass-sulfur composites were prepared by the precipitation method, and the effect of varying carbon black content was studied. The results showed that glass addition improved the battery performance due to the high ion-conductivity of its structural motif. The 75 % glass variant demonstrated the best results, in both the low carbon and high carbon cases. The cyclic voltammetry (CV) and electrical impedance spectroscopy (EIS) measurements showed that glass-sulfur composites had lower resistivity than pure sulfur, which was beneficial for battery performance. The XANES analysis revealed that the incorporated glass interacted with and modified the properties of sulfur, leading to a higher proportion of sulfur in the -1 oxidation state (S−1). This suggests that the high proportion of S−1 phase benefitted battery capacity. Overall, glass-sulfur composites prepared using the precipitation method and incorporating a high content of carbon show promise as a novel and improved cathode material for LSBs.

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