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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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Rapid Detection of Perfluorooctanesulfonic Acid Using Surface-Enhanced Raman Spectroscopy and Deep Learning
(2025-10-07)
Juhong, Aniwat
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Li, Bo
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Liu, Yifan
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Yao, Cheng You
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Yang, Chia Wei
Per- and polyfluoroalkyl substances (PFAS) are a large group of human-made chemicals that have been widely used in industry and consumer products. Perfluorooctanesulfonic acid (PFOS) is a ubiquitous type of PFAS, which is extremely stable chemicals that have been persistent in the environment for many years. The accumulation of PFOS in the human body can lead to various unfavorable health issues related to the immune, metabolic, and endocrine systems. The conventional PFOS detection method utilizes liquid chromatography coupled with a mass spectroscopy system that typically involves a lengthy and complex procedure. Herein, we propose to develop a low-cost and rapid test approach based on surface-enhanced Raman spectroscopy (SERS) and deep learning for PFOS detection. The gold nanoparticle SERS substrates utilized in this study can significantly enhance the Raman signal of PFOS in solution at a low concentration. PFOS detection and quantification in water using the SERS-based substrate are carried out by measuring Raman peak intensities of PFOS in solution at a range of low concentrations and comparing them to the signal of a blank SERS substrate background. The results show that the SERS substrate can achieve a detection limit as low as 0.0005 ppb. In addition, we propose a demultiplexing deep learning model, which can generate high signal-to-noise ratio (SNR) PFOS spectra from the noisy mixture of PFOS and background Raman spectra. Average cross-correlation and mean absolute error (MAE) are utilized to evaluate the similarity between the demultiplexed and denoised PFOS Raman spectra (output of deep learning) and their ground truths. The proposed model can achieve an encouraging result with high average cross-correlation and low average MAE of 0.9622 ± 0.0667 and 0.0034 ± 0.0024, respectively.
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Rational concept for fully designing metal-oxynitride films through reactive gas-timing magnetron sputtering: A case study on zinc oxynitride film
(2025-08-10)
Khemasiri, Narathon
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Chananonnawathorn, Chanunthorn
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Horprathum, Mati
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Pornthreeraphat, Supanit
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Saekow, Bunpot
Amorphous metal-oxynitride films—particularly zinc oxynitride (ZnON)—are emerging as promising materials for next-generation high-speed switching electronics, due to the absence of a potential barrier above the conduction band, unlike metal-doped ZnO. However, conventional reactive magnetron sputtering often face challenges in precisely controlling in an anion ratio, N/(N + O), because of the different reactivities of nitrogen and oxygen gases. In this work, we present a strategy to precisely control both the crystal structure and N/(N + O) ratio in ZnON films using a reactive gas-timing technique. By adjusting the oxygen gas-timing sequence (t<inf>O₂</inf>), we selectively induce different crystalline phases, which are closely related to the nitridation and oxidation of the sputtered Zn atom/cluster. This technique facilitates effective N incorporation into ZnO, enabling a broad range of N/(N + O) ratios from 0.048 to 0.964 and optical band gap variations from 1.49 eV to 3.22 eV. At an optimal t<inf>O₂</inf>, an amorphous phase is formed, attributed to a balanced nitridation and oxidation rate of the sputtered Zn atom/cluster that suppresses crystallization. The resultant amorphous ZnON film exhibits a high carrier mobility of 84.81 cm²/Vs, which is 1.16-fold and 35.89-fold greater than those of the cubic and hexagonal ZnON films, respectively. Our findings highlight the effectiveness of the reactive gas-timing technique as a powerful tool for the rational design of metal-oxynitride films, paving the way for their application in advanced electronic devices.
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Laser-induced graphene electrochemical immunosensors for rapid and sensitive serological detection: A case study on dengue detection platform
(2025-06-01)
Inlumphan, Supawee
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Wongwiriyapan, Winadda
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Khemasiri, Narathon
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Rattanawarinchai, Prapakorn
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Leepheng, Piyawan
Here, we present a diagnostic on a chip platform based on laser-induced graphene (LIG) electrochemical immunosensors for serological detection. The electrochemical immunosensors are fabricated through CO<inf>2</inf> laser induction on polyimide (PI) sheets. Optimal electrochemical activity of LIG electrodes is obtained under optimized conditions of laser fluence. To verify the application, the serological detection platform was demonstrated. After functionalization with dengue virus (DENV) antigen, the LIG electrochemical immunosensors are able to sense the presence of mouse anti-flavivirus monoclonal (4G2) antibody in a wide linear working range of 25–20,000 ng/ml with the limit of detection (LOD) of 17.41 ng/ml. A specific recognition with 4G2 antibodies against with media protein and isotype is confirmed. Furthermore, the reliability of LIG electrochemical immunosensors compared to conventional enzyme-linked immunosorbent assay (ELISA) is verified through the NS1 antibodies identification in human blood serum clinical samples at room temperature. Our results highlight that the LIG-based electrode is a promising platform for electrochemical immunosensors, aimed at developing reliable and practical diagnostic tools for serological detection. These tools enable early diagnosis of infectious diseases, as well as non-invasive and rapid screening.
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Selective formations of antimony-dopant for highly sensitive nitrogen dioxide responsive behavior of tin oxide-based chemiresistive sensor
(2025-02-15)
Rattanawarinchai, Prapakorn
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Khemasiri, Narathon
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Rahong, Sakon
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Rangkasikorn, Adirek
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Kayunkid, Navaphun
Here, selective formation of antimony (Sb) dopant species responsible for highly sensitive gas sensors based on tin oxide (SnO<inf>2</inf>) film grown via pulsed laser deposition is presented. By elevating a forming energy through controlling substrate temperature, not only crystallinity of Sb-SnO<inf>2</inf> (ATO) is notably enhanced but the Sb5 + also predominantly replace at Sn4+ site rather than Sb3+ counterpart. Such Sb-species selection plays a crucial role on the density of oxygen vacancy and free electron enabling to rationally design conductive behaviour of ATO film from insulative to degenerated semiconductor. As a practical example, detection of nitrogen dioxide (NO<inf>2</inf>) gas is selected as an application model. We found a narrow window for high NO<inf>2</inf> sensing performance of ATO film which strongly corresponds with the amount of carrier density. At certain window, ATO film exhibits high NO<inf>2</inf> response of 24.65 (10 ppm) and low limit of detection of 0.5 ppm, which is 5-fold higher and 10-fold lower than that of undoped-SnO<inf>2</inf>, respectively. Our finding demonstrates a facile approach to design over the chemical state, defect, and conductivity of the active sensing layer, allowing us to achieve an excellent sensing performance of functional materials conjugated to a nano-electronic platform.
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Design and Implementation of a High-Field NdFeB Magnet System for Investigating the Spin Seebeck Effect
(2025-01-01)
Nachaithong, Theeranuch
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Wongjom, Chalothon
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Samransuksamer, Benjarong
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Phumying, Santi
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Pongophas, Ekkarat
The generation of pure spin current through thermal gradients, known as the spin Seebeck effect (SSE), has garnered significant interest in spintronics. In this study, we design and construct a permanent magnetic instrument setup to generate a variable external magnetic field using NdFeB permanent magnets to observe the SSE. The experimental setup is composed of three crucial components: the magnetic field, the temperature gradient, and electronic control systems. Si/yttrium iron garnet (YIG)/platinum (Pt) and Si/nickel (Ni) samples, prepared via sputtering techniques, were utilized for standard calibration purposes. The results show that the external magnetic field produced by NdFeB varies with the gap distance between the two magnetic poles, following an exponential decrease in field strength with increasing gap distance. The magnetic field at the center can be adjusted from ±20 to ±5000 Oe. The temperature gradient stabilizes after approximately 10 min, with a temperature difference ( ΔT ) between the heated and cooled sides ranging from 0 to 30 K. For instrument testing, we performed magnetic field and angle-dependent measurements on Si/YIG/Pt and Si/Ni samples. The results indicate that the magnetic field dependence of the permanent magnet instrument (PMI) does not exhibit the voltage loop switching seen with an alternative magnetic coil (AMC) but shows analogous behavior at high magnetic fields. Moreover, the angle dependence of both PMI and AMC yielded comparable results. In conclusion, our PMI setup procedures effectively facilitate the observation of the SSE.
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A flexible formaldehyde sensor based on palladium nanoparticles-polyvinylpyrrolidone-carbon nanotubes-nanocellulose composite films
(2025-01-01)
Chobsilp, Thanattha
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Muangrat, Worawut
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Inpaeng, Saowaluk
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Tedsree, Karaked
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Yordsri, Visittapong
A flexible formaldehyde sensor with high sensitivity was successfully fabricated by integrating palladium (Pd) nanoparticles, polyvinylpyrrolidone (PVP), multi-walled carbon nanotubes (MWCNTs) and nanocellulose (NC) into composite films. The flexible composite films were fabricated via vacuum filtration. The morphology, structure, composition, crystallinity, and functional group of as-fabricated sensing materials were characterized by scanning electron microscopy, transmission electron microscopy, electron probe microanalyzer, Raman spectroscopy, and Fourier transform infrared spectrometer. Pd nanoparticles-PVP-MWCNTs-NC (Pd-PVP-MWCNTs-NC) composite films exhibited an 11-fold increase in formaldehyde sensitivity compared to MWCNTs-NC composite films. The excellent sensing performances of Pd-PVP-MWCNTs-NC sensors were attributed to the combination of Pd nanoparticles and PVP. The enhanced sensitivity is attributed to the synergistic effect of the high electron transfer from formaldehyde molecule to Pd nanoparticles and swelling of PVP due to sorption of formaldehyde molecule. Pd-PVP-MWCNTs-NC sensors still maintained good response under bending angle up to 30° and 300 bending cycles. The results demonstrate that the Pd-PVP-MWCNTs-NC composite films are highly promising in terms of sensitivity and flexibility for sub-ppm level formaldehyde detection at room temperature.
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Spin Seebeck effect and large spin conversion in amorphous Fe2TiSb/polycrystalline Y3Fe5O12 thin films
(2024-05-30)
Wongjom, Poramed
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Wongjom, Chalothon
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Pongophas, Ekkarat
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Infahsaeng, Yingyot
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Maiaugree, Wasan
This study investigates spin current generation in a Fe<inf>2</inf>TiSb/Y<inf>3</inf>Fe<inf>5</inf>O<inf>12</inf> multi-layer thin film as prepared via the magnetron sputtering method. Comprehensive characterization techniques are employed to assess film properties, including X-ray diffraction, energy-dispersive X-ray spectroscopy, Scanning electron microscopy, and Vibrating sample magnetometer. The Y<inf>3</inf>Fe<inf>5</inf>O<inf>12</inf> material exhibits a polycrystalline ferromagnetic insulator behavior, while the 20 nm-thick Fe<inf>2</inf>TiSb film displays small ferromagnetic metal properties with an amorphous structure. Spin current analysis utilizes the longitudinal spin Seebeck effect configuration, considering magnetic field and temperature dependencies and the results show that spin conversion within the Fe<inf>2</inf>TiSb/Y<inf>3</inf>Fe<inf>5</inf>O<inf>12</inf> structure is influenced by both the spin Seebeck effect and the anomalous Nernst effect, resulting in an overall spin signal enhancement. The spin Seebeck coefficient of Fe<inf>2</inf>TiSb/Y<inf>3</inf>Fe<inf>5</inf>O<inf>12</inf> was approximately 0.103 μV/K within a magnetic field of 300 mT.
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Fabrication of Al/Au hybrid SERS substrate using laser engraving for rapid detection of melamine and its analogues by hand-held Raman spectrometer
(2024-05-01)
Wongwasuratthakul, Puwasit
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Aumpalop, Weerada
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Chakaja, Chaiwat
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Satapornchai, Pemika
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Eiamsamut, Ploypailin
Surface-enhanced Raman spectroscopy (SERS), combined with a handheld Raman spectrometer, was utilized for the rapid and highly sensitive detection of melamine and its analogues. The investigation focused on the hybrid micro-nano structures of SERS-active substrates, fabricated by laser engraving aluminum (Al) sheets and depositing gold (Au) nanoparticles using magnetron sputtering. The laser engraving frequency was varied to get optimum SERS substrate. The fabricated SERS substrates were tested with rhodamine 6G (R6G) to optimize the Raman signal and subsequently detect melamine and its analogues viz., cyanuric acid, ammeline, ammelide in milk samples. The results demonstrated that a laser frequency of 20 kHz was the optimal condition for fabricating a micro-nano Al template with a depth of 61.21 μm, providing the highest Raman signal for R6G. The limit of detection (LOD) for melamine in mild acid solution and milk samples were determined to be 1x10-5 M and 1x10-4 M, respectively. The laser-engraved Al sheet technique offers a cost-effective approach for SERS substrate fabrication. The integration of the Al/Au hybrid SERS substrate with a hand-held Raman spectrometer demonstrates significant potential for detecting melamine and its analogues in realistic environments.
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Porous Electrospun Carbon Nanofibers Bearing TiO2 Hollow Nanospheres for Supercapacitor Electrodes
(2024-03-22)
Wongprasod, Suchunya
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Tanapongpisit, Nantawat
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Laohana, Peerawat
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Huyen Nguyen, Thi My
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Van, Hoang Quy
A facile fabrication method was introduced to enhance the specific surface area and porosity of the carbon nanofibers. The carbon nanofibers bearing TiO<inf>2</inf> hollow nanosphere electrodes were synthesized using an electrospinning technique followed by heat treatment. Varying amounts of as-prepared TiO<inf>2</inf> hollow nanospheres were incorporated into the polymer precursor to examine their impact on the electrode enhancement. The electrochemical performance of supercapacitor electrodes composed of carbon nanofibers bearing TiO<inf>2</inf> hollow nanospheres was investigated. Results revealed that the specific capacitance of the bare carbon nanofibers electrode (170 F g-1 at a current density of 0.5 A g-1) was significantly improved upon when embedded with 5 wt % TiO<inf>2</inf> hollow nanospheres of 191 F g-1. Additionally, the carbon nanofibers bearing 5 wt % TiO<inf>2</inf> hollow nanosphere electrodes demonstrated excellent cycling stability, retaining 97% of its initial specific capacitance even after 10000 cycles. Additionally, the electrochemical performance of asymmetric supercapacitors from these electrodes was also demonstrated. These findings highlight the ability of as-prepared TiO<inf>2</inf> hollow nanospheres to improve the efficiency of the carbon nanofibers electrode due to the optimum porosity to the amount of TiO<inf>2</inf> hollow nanospheres in the carbon nanofibers, opening up possibilities for the development of high-performance supercapacitors.

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