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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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Enhancing electrochemical properties of an activated bamboo carbon-based supercapacitor with reduced graphene oxide nanocomposites through pulverizing and mixing in a 3-D high-speed ball mill
(2025-04-01)
Srichaiprapha, Kitima
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Ruttanapun, Chesta
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Sriwong, Chaval
Bamboo-activated carbon (AC-BBC) achieved improved electrochemical properties by compositing it with reduced graphene oxide (rGO) at 1, 3, 5, and 7% weight (wt%). The AC-BBC samples were prepared by annealing bamboo carbon (BBC) powder and a KOH mixture through flowing argon at 900 °C. It was pulverized and mixed using high-speed three-dimensional (3-D) ball milling. rGOx%/3D-AC-BBC (x = 1, 3, 5, and 7 wt%) samples, which are referred to as AC-BBC composites with x% rGO ground by 3-D ball milling, were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Raman spectroscopy techniques. Analysis using scanning electron microscopy (SEM) and specific surface area (SSA) revealed that the rGO5%/3D-AC-BBC sample exhibited the highest specific surface area (SSA), 2239.80 m²/g, with an average pore size of 2.22 nm. Half-cell electrodes had the greatest specific capacities, 301.80 F/g at 0.5 A/g. The symmetric supercapacitor coil cell device showed a capacitance of 85.93 F/g, an energy density of 11.93 Wh/kg, and a power density of 49.56 W/kg. The efficiency retention was reduced to 96.76% after 10,000 cycles. This manuscript presents a high-performance rGO5%/3D-AC-BBC material that can be used for active electrodes to enhance electrochemical properties, making them suitable for electric double-layer capacitor (EDLC) applications.
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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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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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Dielectric and electrochemical properties of hybrid Pt nanoparticles deposited on reduced graphene oxide nanoparticles /poly (vinylidene fluoride) nanocomposites
(2021-06-01)
Karaphun, Attaphol
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Tuichai, Wattana
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Chanlek, Narong
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Sriwong, Chaval
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Ruttanapun, Chesta
Nano-sized platinum (Pt) materials deposited on reduced Graphene Oxide (rGO) nanosheets (hybrid Pt-rGO nanoparticle) were prepared by the seed-mediated growing process using 20 wt% of Pt nanomaterials in rGO suspension. Dielectric properties of hybrid Pt-rGO nanoparticles/poly (vinylidene fluoride) nanocomposites (Pt-rGO/PVDF nanocomposites) were synthesized by a liquid–phase assisted dispersion and hot–pressing methods with different volume fractions (f) of hybrid Pt-rGO nanoparticle loading PVDF nanocomposites. The observed particle size of Pt nanomaterials deposits on rGO nanosheets was 5 nm. The dielectric constant (ε′) of Pt-rGO/PVDF nanocomposites was increased with increasing hybrid Pt-rGO nanoparticle. The volume fraction f<inf>Pt-rGO</inf> ≈0.0786 exhibited excellent ε′ ≈ 86 with very low loss tangent (tanδ) ≈ 0.021 at 1 kHz. High dielectric properties of Pt-rGO/PVDF composite should be ascribed to combination of the micro-capacitor and Maxwell–Wagner–Sillars (MWS) effects. Electrochemical properties of speciﬁc capacitances (C<inf>sc</inf>) and capacity retention of hybrid Pt-rGO nanoparticle electrode were investigated by the cyclic voltammetry and the galvanostatic charge-discharge. Interestingly, the hybrid Pt-rGO nanoparticle electrode displayed maximum C<inf>sc</inf> value of 169.8 F g−1 at the current densities of 0.25 A g−1. This was due to the occurrence of various oxygen functional groups in the rGO- and Pt+ ions as contributing to form of pseudo-capacitance in hybrid Pt-rGO nanoparticle.
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The influence of annealing on a large specific surface area and enhancing electrochemical properties of reduced graphene oxide to improve the performance of the active electrode of supercapacitor devices
(2021-02-01)
Karaphun, Attaphol
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Phrompet, Chaiwat
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Tuichai, Wattana
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Chanlek, Narong
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Sriwong, Chaval
Influence of annealing process on microstructure, large specific surface area and enhancing electrochemical properties to synthesize reduced graphene oxide (rGO) for the supercapacitor electrode was investigated. Thermal annealing process of rGO (rGO_An) was improved crystallinity and electrical conductivity. BET analysis of rGO_An sample exhibited the occurrence of large mesoporous and macrospores with a huge specific surface area of 672.1 m2/g and an average pore size of 46.2 nm, resulting the rGO_An sample activates more electrodes than rGO sample. Specific capacitance (C<inf>s</inf>) was affected by improving conductivity through annealing process with an excellent cycling stability after 750 cycles for GCD tests of 97.32%, which exhibited the highest value and an average energy density of 412.096 F g−1 and 74.5 Wh kg−1, respectively at 1 A g−1. Thus, annealing process can occur with large mesoporous and macrospores pore improving the electrical conductivity and stability to be applied as an electrode in supercapacitor.
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Ag nanomaterials deposited reduced graphene oxide nanocomposite as an advanced hybrid electrode material for Asymmetric Supercapacitor device
(2020-12-30)
Tuichai, Wattana
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Karaphun, Attaphol
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Ruttanapun, Chesta
Asymmetric Supercapacitor (ASC) was effectively fabricated using CR 2032-coin cell based on the positive electrode of the hybrid Ag@rGO nanocomposite and the negative electrode of reduced Graphene Oxide (rGO) material with polyvinyl alcohol (PVA)/6 M KOH electrolyte. The Ag@rGO nanocomposite was prepared through a seed-mediated growing process by a 10 wt% of Ag nanomaterials deposits in suspension rGO 90 wt% which presented a specific capacitance value of 65.9 F g−1 at current density of 0.5 A g−1. Moreover, the rGO electrode with a 5 mg/mL concentration was synthesized by the modified Hummers’ method and revealed a high specific capacitance value of 317.3 F g−1 at current density of 0.5 A g−1. Interestingly, the ASC assembly of Ag@rGO//rGO hybrid energy-storage device provided a wide voltage window of 0.0–1.4 V and showed a specific capacitance (C<inf>sc</inf>) value of 44.17 F g−1 at current density of 3 A g−1. This hybrid energy-storage device indicated specific energy density (E<inf>sp</inf>) of 11.09 W h kg−1 and specific power density (P<inf>sp</inf>) of 2.67 kW kg−1, respectively. It also showed a good cycle stability of 81.5%. The capacitance retention finished at 500 cycles.
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Electrochemical properties of tricalcium aluminate hexahydrate − reduced graphene oxide nanocomposites for supercapacitor device
(2020-08-01)
Phrompet, Chaiwat
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Maneesai, Keerati
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Tuichai, Wattana
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Karaphun, Attaphol
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Sriwong, Chaval
In this study, the influence of reduced graphene oxide (rGO)−Tricalcium Aluminate Hexahydrate (C3AH6) cement nanocomposites on electrochemical properties was investigated. The rGO-C3AH6 nanocomposite samples with various of rGO laoding, such as, C3AH6_rGO-1, 3, 5, 7, 10 and 20 wt.% were easily synthesized by a rapid cement hydration method. The maximum specific surface area and average pore size diameters were 74.20 m2/g and 11.72 nm for C3AH6_rGO-20%. The charge tranfering in C3AH6_rGO nanocomposites was described using band alignments model occurring between C3AH6 and rGO. Interestingly, the increasing of both dielectric property and stability in frequency of C3AH6_rGO composite samples can be explained by the high density of free electron charges on the rGO surface. Moreover, the electrochemical properties of C3AH6_rGO electrodes had excellent capacitive properties displaying the storage charge mechanism of a hybridsupercapacitor behavior. The large rGO content of the C3AH6_rGO nanocomposite capacitor with electrolyte interfaces showed excellent electrochemical performance. The highest value of 80.479 F g −1 was obtained from C3AH6_rGO-20% at a current density of 0.2 A g −1 with cycling stability of 96.51% after 1000 cycles.
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Effect of grain boundary interfaces on electrochemical and thermoelectric properties of a Bi2Te3/reduced graphene oxide composites
(2020-08-01)
Thongsamrit, Wannisa
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Phrompet, Chaiwat
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Maneesai, Keerati
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Karaphun, Attaphol
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Tuichai, Wattana
The electrochemical and enhanced thermoelectric properties of pristine Bi<inf>2</inf>Te<inf>3</inf> and Bi<inf>2</inf>Te<inf>3</inf>/reduced graphene oxide (Bi<inf>2</inf>Te<inf>3</inf> + rGO) composites at 1%, 3% and 5% levels of rGO were synthesized via a simple ultrasonic method. The X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), UV–vis spectrometry (UV–vis) and their electrochemical and thermoelectric properties were measured. The ultrasonic method succeeded in producing rGO nanosheets composited with Bi<inf>2</inf>Te<inf>3</inf> forming grain boundary interfaces of rGO with Bi<inf>2</inf>Te<inf>3</inf>. The resulting samples displayed a continuous network structure of rGO nanosheets in Bi<inf>2</inf>Te<inf>3</inf> + rGO composites for electrons in the conduction band of the Bi<inf>2</inf>Te<inf>3</inf> structure. Electrons were transferred to rGO nanosheets at the interface, contributing electron charge carriers in Bi<inf>2</inf>Te<inf>3</inf> + rGO composites. This indicates band alignment between Bi<inf>2</inf>Te<inf>3</inf> and rGO nanosheets. The Bi<inf>2</inf>Te<inf>3</inf> + rGO composites exhibited an increasing storage charge mechanism of electrical double layer capacitors with greater rGO contents. The Bi<inf>2</inf>Te<inf>3</inf> + rGO composites displayed negative a Seebeck coefficient for thermoelectric materials. The highest ZT value was 0.17 in the bulk 1% Bi<inf>2</inf>Te<inf>3</inf> + rGO composite. Improved electrochemical and thermoelectric properties of the Bi<inf>2</inf>Te<inf>3</inf> + rGO 1% composite resulted from the interaction of the grain boundary interfaces of rGO nanosheets with pristine Bi<inf>2</inf>Te<inf>3</inf> following the model of band alignment between Bi<inf>2</inf>Te<inf>3</inf> and rGO nanosheets.

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