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Effect of Hexamethylenetetramine on Physical, Structural, and Photocatalytic Properties of ZnO Nanostructures Synthesized via One-Step Sol-Gel Process
(2026-07-01)
Songpanit, Maneerat
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Boonyarattanakalin, Kanokthip
;
Basu, Soumya
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Okumura, Hideyuki
;
Ishihara, Keiichi N.
Wastewater contamination with synthetic organic dyes is a significant environmental challenge. Zinc oxide (ZnO) has attracted considerable attention as a non-toxic, multifunctional material for electronics, optics, piezoelectric devices, and photocatalysis, where its performance is strongly governed by morphology. In this work, we investigate the effect of hexamethylenetetramine (HMTA) on the formation and photocatalytic behavior of ZnO nanostructures synthesized from different zinc precursors, namely zinc acetate and zinc nitrate, via a one-step sol–gel process at low temperature without any post-treatment. All samples crystallize in the hexagonal wurtzite phase without detectable impurities, and the incorporation of HMTA leads to smaller, more uniform rod- and flake-like nanostructures. Although ZnO derived from zinc acetate without HMTA exhibits the highest specific surface area, ZnO synthesized in the presence of HMTA shows more favorable crystallinity, morphology, and pore connectivity, which together enhance charge separation and reactive oxygen species generation. As a result, ZnO samples synthesized with HMTA exhibit improved photocatalytic degradation of rhodamine B under UV irradiation.
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Preparation of Composite Films of Rod-like Structure of ZnO and Corn Starch for Bending Sensor
(2026-01-01)
Feemuchang, Kitikamol
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Onlaor, Korakot
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Tunhoo, Benchapol
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Thiwawong, Thutiyaporn
In this work, rod-like structure zinc oxide (R-ZnO) was synthesized by a hydrothermal process with the hydrothermal times of 3, 5, and 10 h. The effect of reaction time was reflected in the physical properties of the prepared R-ZnO, such as crystalline structure, shape geometries, and optical properties. Then, a bending device was fabricated with starch composite films and the rod-like structure of zinc oxide with different R-ZnO concentrations. The fabricated device exhibited flexibility characteristics at various bending angles. The composite film of corn starch and 1%wt. R-ZnO at a hydrothermal reaction time of 10 h demonstrated a high sensitivity at 89.5% with a gauge factor of 1.58. Moreover, the device of corn starch composited with R-ZnO exhibited fast response/recovery time of 0.23/0.15 s with high stability of bending cycle of more than 1,600 cycles. Therefore, the composite films of R-ZnO and natural starch are strong potential candidates for bending devices.
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Hydrothermally grown ZnO nanorods on cellulose filter papers for piezo-photocatalysis applications
(2025-12-01)
Songpanit, Maneerat
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Limwichean, Saksorn
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Horprathum, Mati
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Boonyarattanakalin, Kanokthip
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Pecharapa, Wisanu
ZnO nanorods were grown on cellulose filter paper using a one-pot hydrothermal method, varying concentrations at 10, 50, and 100 mM. The growth of ZnO nanorods exhibited high crystallinity in ZnO wurtzite confirmed by XRD and SEM results. Meanwhile, the specific surface area of all samples decreased following higher seed concentrations. To evaluate the photocatalytic performance, all samples were tested using RhB degradation under xenon irradiation, ultrasonic treatment, and a combination of xenon and ultrasonic irradiation. The highest ZnO catalytic performance in photocatalytic and piezo-catalytic reactions was observed at a 50 mM seed layer concentration attributing to the strong crystallinity along the c-axis direction and high aspect ratio of nanorods. Moreover, the optimal condition for piezo-photocatalytic applications was achieved by the seed layer concentration at 10 mM, resulting in shorter nanorods and a large surface area, providing better mechanical stability under stress corresponding to enhancing the charge recombination in photocatalytic processes.
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Modification of acid–base properties of metal-doped ZnO catalysts for the transesterification of propylene carbonate with methanol to dimethyl carbonate
(2025-04-01)
Ieamviteevanich, Pimchanok
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Kim-Lohsoontorn, Pattaraporn
;
Seeharaj, Panpailin
This study investigated the effect of metal dopants on the surface properties of ZnO-based catalysts for the transesterification of propylene carbonate (PC) with methanol to produce dimethyl carbonate (DMC). A series of metal-doped ZnO nanocatalysts (M-ZnO, where M is Ca2+, Cu2+, Ce3+, La3+, and Y3+ with the mol ratio of Zn2+/Mx+ = 4) were prepared by a simple co-precipitation method followed by calcining in air at 673 K for 5 h. Introducing different metal cations into the ZnO system decreased crystallite size and created surface defects of exposed cations and oxygen vacancies, increasing surface-active acid and basic sites. The catalytic performance for DMC production was ranked as follows: Ca-ZnO < Cu–ZnO < ZnO < Ce-ZnO < Y-ZnO < La-ZnO. La-ZnO showed the highest performance of all catalysts, with 67% PC conversion, 67% DMC selectivity, and 45% DMC yield. The improvement of catalytic activity was correlated with an increase in the concentration of moderate and strong acid–base functionalities on the La-ZnO surfaces for participating in the reaction of PC and methanol to form DMC.
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Synergy of functionalized activated carbon and ZnO nanoparticles for enhancing photocatalytic degradation of methylene blue and carbaryl
(2024-10-01)
Rungsawang, Tipawan
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Krobthong, Sucheewan
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Paengpan, Krisanachai
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Kaewtrakulchai, Napat
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Manatura, Kanit
This study proposes preparing ZnO and ZnO/activated carbon (AC) for photocatalytic applications. ZnO and AC were synthesized using precipitation and carbonization processes, respectively. Particle sizes of ZnO and ZnO/AC were estimated at 121–135 nm. The crystalline structure analysis confirmed the presence of hexagonal wurtzite structures in ZnO. Microcrystalline graphite and amorphous carbon structures were observed in AC. The combination of these characteristics was observed in ZnO/AC. ZnO/AC exhibited an increase in surface area from 25.36 to 29.86 m2/g and a decrease in pore diameter from 5.66 to 4.31 nm. The chemical states of ZnO and AC remained unchanged. Therefore, the nanocompound structure of ZnO/AC can be inferred. The ZnO/AC nanocompounds were then employed to degrade methylene blue (MB) dye and carbaryl (CBR) insecticide, demonstrating excellent photocatalytic performance compared to pure ZnO. The apparent degradation rate constant reached an average value of 3.49 × 10−3 and 16.25 × 10−3 min−1 for MB and CBR, respectively. AC functions as carrier collectors in the ZnO/AC nanocompound structures due to the suitable energy band level for facilitating electron and hole transfers. This results in recombination suppression and prolonged lifetime, thus enhancing photocatalytic activity. The finding suggests the potential use of ZnO/AC nanocompounds to degrade agricultural chemicals in contaminated natural water under sunlight.
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A novel photocatalyst of Y2O3-BaO-ZnO ternary system for enhanced photocatalytic degradation of carbofuran insecticide
(2024-08-01)
Sujinnapram, Supphadate
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Krobthong, Sucheewan
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Moungsrijun, Sasimonton
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Boonruang, Chatdanai
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Kaewtrakulchai, Napat
A novel Y<inf>2</inf>O<inf>3</inf>-BaO-ZnO ternary system was synthesized via precipitation of a mixture of Y(NO<inf>3</inf>)<inf>3</inf>.6 H<inf>2</inf>O:Ba(NO<inf>3</inf>)<inf>2</inf>:Zn(NO<inf>3</inf>)<inf>2</inf>.6 H<inf>2</inf>O using some Fibonacci sequences. The Y<inf>2</inf>O<inf>3</inf>-BaO-ZnO was applied to the photocatalyst to investigate the degradation of carbofuran insecticide. The Y<inf>2</inf>O<inf>3</inf>-BaO-ZnO prepared at the sequence ratio of 5:8:13 (YBZ5) exhibited the highest photocatalytic performance. Morphological characterization showed that the particle size of the YBZ5 sample was significantly smaller than that of ZnO by over half, possibly providing high surface areas. The crystalline structure, functional group, and surface chemical composition investigations confirmed the presence of Y<inf>2</inf>O<inf>3</inf>, BaO, and ZnO. The fluorescence study exhibited no difference. Based on band gap energy and energy band alignment analysis, the Y<inf>2</inf>O<inf>3</inf>-BaO-ZnO ternary system demonstrated a well-aligned valence band. The energy band alignment analysis revealed a good alignment of the valence band for continuous hole transport in the Y<inf>2</inf>O<inf>3</inf>-BaO-ZnO ternary system. The alignment induces charge separation which reduces recombination and provides efficient active carriers at the surfaces of the photocatalyst, allowing reactions with toxic molecules. Therefore, the synergistic function of high surface areas and appropriate energy band alignments of the novel Y<inf>2</inf>O<inf>3</inf>-BaO-ZnO ternary system is considered the crucial factor in the enhancement of photocatalytic performance.
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Structural, Optical, and Electrical Properties of Sputtered ZnO Thin Films and Their Application in Transparent Memory Devices
(2022-12-01)
Tunhoo, B.
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Kaewkusonwiwat, S.
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Thiwawong, T.
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Onlaor, K.
We report on the fabrication of ZnO thin films using a lab-made DC sputtering process. The ZnO films were prepared at several applied sputter voltages at fixed deposition times. The properties of the deposited films were characterized by x-ray diffraction, x-ray photoelectron spectroscopy, field-emission scanning electron microscopy, and UV–visible spectroscopy. The ZnO thin films exhibited a polycrystalline phase in the dominant (100) plane, with film thicknesses in the order of approximately 50–80 nm. In addition, a transparent memory device based on the ZnO film was successfully fabricated with a device structure of ITO/ZnO/EVA/ITO. The fabricated device exhibited high optical transparency of approximately 70% in the visible light region. The fabricated memory device demonstrated memory properties with a maximum ON/OFF current ratio of 4.66 × 103 and showed good retention properties.
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High Surface Area ZnO-Nanorods Catalyze the Clean Thermal Methane Oxidation to CO2
(2022-12-01)
Kessaratikoon, Tanika
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Saengsaen, Sawarin
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Del Gobbo, Silvano
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D’Elia, Valerio
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Sooknoi, Tawan
ZnO nanostructures were synthesized by a combination of non-aqueous and aqueous sol-gel techniques to obtain morphologically different ZnO nanostructures, nanorods, and nanopyramids, featuring oxygen vacancies-rich exposed lattice faces and exhibiting different catalytic properties and activity. In particular, ZnO nanorods with high surface area (36 m2/g) were obtained through a rapid, scalable, and convenient procedure. The materials were tested for complete methane oxidation as an important benchmark reaction that is sensitive to surface area and to the availability of oxygen vacancies. Simple ZnO nanorods derived from nanosized quantum dots showed the best catalytic performance that compared well to that of several literature-reported perovskites, mixed metal oxides, and single-metal oxides in terms of T<inf>50</inf> (576 °C) and T<inf>90</inf> (659 °C) temperatures. Such a result was attributed to their high surface-to-volume ratio enhancing the availability of catalytically active sites such as oxygen vacancies whose abundance further increased following catalytic application at high temperatures. The latter effect allowed us to maintain a nearly stable catalytic performance with over 90% conversion for 12 h at 700 °C despite sintering. This research shows that ZnO-based nanomaterials with a high surface area are viable alternatives to oxides of commonly applied (but of potentially limited availability) transition metals (La, Mn, Co, Ni) for the complete combustion of methane when working at moderate temperatures (600–700 °C).
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Sphere-like and flake-like ZnO immobilized on pineapple leaf fibers as easy-to-recover photocatalyst for the degradation of congo red
(2021-04-01)
Deebansok, Siraprapha
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Amornsakchai, Taweechai
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Sae-Ear, Pannagorn
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Siriphannon, Punnama
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Smith, Siwaporn Meejoo
This work reports immobilization of ZnO photocatalyst on very fine pineapple leaf fiber (PALFs) by a by polyelectrolyte coating method, for the removal of colored pollutants from water stream, allowing for simple recovery after use. It also emphasizes on the effect of defect structure containing in ZnO of hierarchical sphere-like and flake-like morphologies on the color removal performance. The photocatalytic activity of ZnO/PALFs for degradation of congo red (CR) dye was examined under static (dark) and UV/visible irradiation conditions, and effective color removal (>95 %) was achieved, as the results of adsorption and photo-oxidation processes. Results from photoluminescence and X-ray photoelectron spectroscopy suggested that the sphere-like ZnO, bearing zinc vacancies (VZn), zinc interstitials (Zni), singly ionized oxygen vacancies (Vo+), and oxygen vacancies (Vo), has superior photocatalytic activity up to 3.6 times compared to that of flake-like ZnO. With the recyclability up to 3 cycles (>84 % color removal efficiencies), the ZnO immobilized on PALFs have shown a great promise as an easy-to-recover photocatalyst for the removal of colored pollutants in wastewater treatment processes.
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Effect of ZnO and BaTiO3Nanoparticle on Partial Discharge Characteristics of Palm Oil Based Nanofluids
(2020-10-25)
Maneerot, Sakda
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Vittayakorn, Wanwilai
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Pattanadech, Norasage
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Soubol, Nichaya
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Yodrayub, Noppol
This paper presents the partial discharge inception voltage (PDIV) and partial discharge extinction voltage (PDEV) of palm oil based on nanofluids with different concentration of ZnO and BaTiO3. Each liquid specimen was prepared in a 2000 ml beaker. The palm oil sample was heated under vacuum in the oven with temperature at 80°C under 200 mbar for 12 hours. Next, these liquids were divided into seven groups according to the amount of ZnO and BaTiO3 nanoparticle. The first group was the unmodified palm oil. The second and third group were palm oil mixed with 0.01% of ZnO and BaTiO3 nanoparticle respectively. The fourth-the seventh group were palm oil mixed with 0.03% and 0.05% ZnO and BaTiO3 respectively. Then all specimens were heated at 80°C under 200 mbar for 12 hours. After that, the PDIV and PDEV of the liquid specimen were investigated using the test circuit according to IEC 60270 using needle-plane electrodes with the needle tip radius of 10 μm. Each group was tested in 6 times. The mean values of PDIV and PDEV were reported. From the test results, it was clear that the types and concentrations of nanoparticle obviously affected the PDIV and PDEV characteristics of the palm oil based nanofluids.

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