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Enhancement of thermoelectric performance and mechanical reliability in electrodeposited chitosan nanofiber-bismuth telluride nanocomposite
(2026-07-01)
Tian, Jianghan
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Gobpant, Jakrit
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Van Toan, Nguyen
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Theekhasuk, Nattharika
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Pham, Cong Kha
Thermoelectric generators (TEGs) offer a promising route for converting waste heat into electrical energy; however, the practical implementation of high-performance micro-TEGs (μTEGs) is limited by the material performance and mechanical fragility of thick bismuth telluride (Bi<inf>2</inf>Te<inf>3</inf>) films. Although thick thermoelectric layers are required to sustain sufficient temperature gradients, conventional fabrication often induces residual stress, leading to cracking and structural failure. In this work, we introduce a sustainable synthesis strategy by incorporating bio-derived chitosan nanofibers (ChNFs) into the electrodeposition process. The amino and hydroxyl functional groups of ChNFs promote interfacial bonding and nucleation, enabling the rapid growth of dense, crack-free composite films with thicknesses up to 1000 μm. The introduction of ChNFs also creates abundant phonon-scattering interfaces, significantly reducing lattice thermal conductivity from 1.48 to 0.29 W m−1 K−1 and resulting in a 303% increase in the room-temperature figure of merit (ZT), from 0.12 to 0.50. At an optimal loading of 0.0123 wt%, the composite films exhibit a 15% increase in hardness while maintaining structural integrity. These results demonstrate a multifunctional materials design strategy that simultaneously enhances thermoelectric performance, mechanical robustness, and fabrication scalability. The ChNF–Bi<inf>2</inf>Te<inf>3</inf> nanocomposites provide a viable green pathway for developing reliable thick films for next-generation self-powered electronics and compact waste-heat harvesting systems.
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Structural, morphological, optical, and electrochemical properties of Zn-doped CeO2/rGO nanocomposites
(2025-04-01)
Utara, Songkot
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Salidkul, Nuchjaree
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Karaphun, Attaphol
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Sonsupap, Somchai
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Chanlek, Narong
Metal-doped cerium oxide has recently attracted the interest of researchers worldwide because of its various applications in different fields such as supercapacitors, high-sensitivity electrodes or photocatalytic. Metal-doped cerium oxide can be improved utilizing a variety of metals and composites with enhanced conductivity, which advances materials science in semiconductor processing. In this study, undoped and Zn-doped CeO<inf>2</inf> nanoparticles at 5, 10, 15, and 20 at.% were reacted with reduced graphene oxide (rGO) using a hydrothermal method. They were heated at 150 °C for 12 h and then processed in an ultrasonic reactor (20 kHz) at 25 ± 1 °C. Their structural, morphological, elemental, optical, and electrochemical properties were systematically characterized. The calculated average crystallite sizes of CeO<inf>2</inf> peaks ranged from 4.60 ± 0.2 to 12.0 ± 0.4 nm. These samples exhibited a single CeO<inf>2</inf> phase corresponding to a face-centered cubic structure, except for 20 at.% Zn-doped CeO<inf>2</inf>/rGO, which presented a ZnO phase. The samples had lower band gap values than expected for undoped CeO<inf>2</inf> nanoparticles, higher valence states due to their Ce3+/Ce4+ ratios, and a large surface area, 242 m2/g, due to Zn-doping in CeO<inf>2</inf> samples. The highest specific capacitance values achieved were 88.49 F/g at 5 mV/s and 134.01 F/g at 0.5 A/g for undoped CeO<inf>2</inf>/rGO. Zn-doping resulted in decreased capacitive behavior with specific capacitance values in the range of 70.78–81.00 F/g at 5 mV/s and 79.24–101.43 F/g at 0.5 A/g. This study for synthesizing Zn/CeO<inf>2</inf>/rGO ternary nanocomposites produced materials with improved band gaps, valence states of Ce3+/Ce4+ ratios, and greater surface area for improved electrocatalytic performance.
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Antifungal copper nanocomposite-rubber compound for tree wound dressings
(2024-12-15)
Noppradit, Benjaporn
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Uthaipan, Nattapon
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Klinnawee, Lompong
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Kongtragoul, Pornprapa
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Phengdaam, Apichat
This study combines copper nanoparticles (CuNPs) with a rubber compound to develop a tree wound dressing that reduces tree mortality from infections, utilizing broad-spectrum antifungal and adhesive properties of composite material. Phytotoxicities of CuNPs with an average size of 6 nm were significantly lower than those of Cu ions, evaluated by the germination index using lettuce seeds and membrane integrity index using stems of rubber seedling. After that, the synthesized CuNPs were then loaded into a natural rubber (NR) latex compound at concentrations ranging from 0 to 90 mg/L to produce a CuNP composite adhesive. The shear strength, representing adhesion on wood, was evaluated using lap shear testing, revealing a 50 % reduction in maximum force at the highest CuNP loading. This loss of shear strength was attributed to interference by copper ions in the vulcanization of the NR latex compound, as indicated by FT-IR spectroscopy. After that, the CuNP composite adhesive was formed into a film to test antifungal properties against Colletotrichum spp. Based on the in vitro plate inhibition zone assay, 10 mg/L of CuNPs inhibited the growth of Colletotrichum spp. The size of inhibited zone was significantly increased by 150 and 300 % when concentrations of CuNPs were 70 and 90 mg/L, respectively. This research provides the first evidence of the low phytotoxicity of CuNPs compared to copper ions at equivalent concentrations and demonstrates the efficacy of CuNP composites with NR compounds as tree wound dressings.
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X-ray characterization, structural analysis, antibacterial activity, and self-cleaning property of Cu-doped TiO2-SiO2 nanocomposite prepared by sonochemical process
(2024-12-01)
Mekprasart, Wanichaya
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Songpanit, Maneerat
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Sanyen, Thanyapa
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Samart, Sutichai
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Chutipaijit, Sutee
TiO<inf>2</inf>-SiO<inf>2</inf> nanocomposites with different copper (Cu) precursor loadings were prepared by a one-step sonochemical process. The mole ratio of Cu precursor in TiO<inf>2</inf>-SiO<inf>2</inf> composite was varied at 0.004, 0.008, 0.020, and 0.040, respectively. The specific X-ray characterization techniques on crystalline structure, chemical composition, and chemical states of Cu-doped TiO<inf>2</inf>-SiO<inf>2</inf> composite were carried out by X-ray diffraction technique (XRD), X-ray fluorescence (XRF), and X-ray photoelectron spectroscopy (XPS), respectively. Surface morphology and chemical bonding of Cu-doped TiO<inf>2</inf>-SiO<inf>2</inf> composite were monitored by field emission scanning electron microscope (FE-SEM) and Fourier transform infrared spectrophotometer (FTIR). For antibacterial properties, the inhibition zone of antimicrobial activity was investigated by varying amounts of Cu precursors in the TiO<inf>2</inf>-SiO<inf>2</inf> composite. After that, Cu-doped TiO<inf>2</inf>-SiO<inf>2</inf> composite powder with different Cu precursor ratios was mixed in PMMA solution and deposited on glass slides to study the optical property and hydrophilicity by UV-VIS-NIR spectrophotometer and contact angle method. XRD patterns of Cu-doped TiO<inf>2</inf>-SiO<inf>2</inf> nanocomposites show the formation of the main TiO<inf>2</inf> anatase phase with the ultrafine particles observed by FE-SEM images. FT-IR spectra of the composites are assigned to the prominent peaks of the Ti-O-Ti and Ti-O-Si bond relating to the TiO<inf>2</inf>-SiO<inf>2</inf> host matrix. Meanwhile, TiO<inf>2</inf>-SiO<inf>2</inf> composites with Cu precursor at 0.004 mol ratio can significantly enhance the antibacterial activity with a large inhibition zone. The contact angle value of Cu-doped TiO<inf>2</inf>-SiO<inf>2</inf> nanocomposite film at 0.040 Cu precursor mole ratio in the TiO<inf>2</inf>-SiO<inf>2</inf> matrix resulted in the optimized composite ratio for achieving a hydrophilic surface on the substrate.
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Magnetic and ultrasonic integrated photocatalytic hydrogen evolution effects with Nanosize CoOCu2OZnO and TiO2 decorated on reduced graphene oxide
(2023-12-01)
Areerob, Yonrapach
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Meng, Zeda
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Ullah, Kefayat
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Wijaya, Karna
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Otgonbayar, Zambaga
In this study, metal oxide composite (CoOCu<inf>2</inf>OZnO) and TiO<inf>2</inf> on graphene oxide composite (CCZ−G−T) were synthesized to improve visible light-driven H<inf>2</inf> evolution through the addition of a cation scavenger, ultrasonic effect, and magnetic field effect. The synthesized nanocomposites were characterized through structural, surface, and electrochemical analyses with band structure. The photocatalyst showed hydrogen production of 792 μmol·g−1 for 4 hours. Moreover, this CCZ−G−T photocatalyst exhibits relatively high photocatalytic activity at (530−810) μmol·g−1 when using a scavenger, 1,190 μmol·g−1 when using a magnetic field of 0.14 T, and 1,230 μmol·g−1 when using ultrasonic waves. The CCZ−G−T composite exhibited 630 μmol·g−1 under a magnetic field condition of 0.14 T for 1 hour, which was significantly higher than the hydrogen production rate of 510 μmol·g−1 under ultrasonic conditions. The current study provides new insights into the magnetic field effect on the hydrogen evolution reaction (HER) of graphene-based photocatalysts.
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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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