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Hydrothermal Synthesis of MnO2 and Hemp-Derived Activated Carbon Composites for Tailored Electrochemical Performance
(2026-07-22)
Klangvijit, Kanisorn
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Bowornthommatadsana, Khemjiranee
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Reilly, Mayuree Phonyiem
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Obata, Michiko
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Fujishige, Masatsugu
This study investigates hydrothermal synthesis of manganese dioxide composited with hemp-derived activated carbon (MnO<inf>2</inf>/AC) as electrodes for supercapacitors. The effects of key hydrothermal parameters, including carbon ratio, reaction temperature, and reaction time were systematically examined. Phase-pure α-MnO<inf>2</inf> was uniformly anchored on carbon framework. Morphology of MnO<inf>2</inf> evolved from nanowalls to well-defined nanorods with increasing reaction temperature and time. Meanwhile, the specific surface area of MnO<inf>2</inf>/AC decreased from 1712 to 1538 m2 g−1 due to partial pore blocking, while a predominantly mesoporous structure was retained. Electrochemical measurements in 1 M Na<inf>2</inf>SO<inf>4</inf> demonstrate that the optimized MnO<inf>2</inf>/AC composites achieve a specific capacitance of 216.8 F g−1 at 1 A g−1. Charge-storage mechanism analysis reveals a balanced contribution between surface-controlled capacitive processes and diffusion-controlled pseudocapacitance, which is directly correlated with preserved mesoporosity and moderate MnO<inf>2</inf> coverage. When the MnO<inf>2</inf>/AC composites were assembled into an asymmetric supercapacitor using AC as the negative electrode, the device operates stably up to 2.4 V and delivers outstanding cycling stability over 95% after 22,000 charge–discharge cycles at 5 A g−1. These results demonstrate that controlled growth of MnO<inf>2</inf>, rather than maximum oxide loading, is essential for optimizing charge-storage mechanisms and achieving high-performance biomass-derived supercapacitor electrodes.
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Nondestructive Localization of Subvisual Defects in Laser-Induced Graphene via Machine-Learning-Assisted Electrical Resistance Tomography
(2026-06-16)
Minakawa, Keiya
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Takanashi, Kotaro
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Kimura, Yuki
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Klamchuen, Annop
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Wongwiriyapan, Winadda
Although conventional imaging techniques excel at capturing structural changes, they frequently overlook functional degradations that lack morphological signatures. Here, we demonstrate machine-learning-assisted electrical resistance tomography (ML-ERT) as a robust modality for the rapid, nondestructive localization of “subvisual” defects in porous laser-induced graphene (LIG). By employing masked O<inf>2</inf> plasma irradiation, we introduced localized defects that exhibit a dramatic resistance surge up to 4 orders of magnitude while remaining indistinguishable under visual and electron microscopy. Our ML-ERT framework, powered by a one-dimensional convolutional neural network inverse solver, successfully pinpointed these hidden failures once the resistance contrast reached a threshold of R/R<inf>0</inf> ≥ 6.71. Furthermore, 3D finite element analysis revealed that the tomographic contrast is driven by an effective conductive volume loss exceeding 30%, identifying the degradation of internal conductive pathways as the primary mechanism. These results establish ML-ERT as a high-sensitivity diagnostic tool capable of visualizing electrically critical but optically invisible failures, providing a definitive solution for the quality control of large-area carbon electronics.
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Multifunctional Solvent Molecule Realizing High-Performance Elastic Polymer Electrolytes for Lithium Metal Batteries
(2025-11-26)
Nipatwarakan, Pimchanok
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Song, Junlin
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Cui, Yujie
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Guo, Decai
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Song, Yongyi
Solid-state polyurethane electrolytes offer excellent elasticity, which can significantly improve the interfacial ion transport of solid-state lithium metal batteries. However, pure polyurethane electrolytes suffer from poor Li+ conductivity. Herein, a multifunctional solvent molecule, trifluoro-N,N-dimethylacetamide (TFDMA), is introduced to modify the thermoplastic polyurethane (TPU) electrolyte, resulting in a composite electrolyte (TPU-TFDMA) with both high mechanical properties and good Li+ transport performance (ionic conductivity = 1.53 × 10–3 S cm–1 and Li+ transference number = 0.50). Experimental characterizations and theoretical simulations reveal that the presence of additional hydrogen-bonding interactions between TFDMA and the TPU chains not only maintains the mechanical strength of TPU but also enhances interfacial stability and effectively inhibits lithium dendrite growth. Furthermore, TFDMA promotes lithium salt dissociation and reduces the coordination between solvent molecules and Li+, facilitating Li+ desolvation and rapid diffusion. TFDMA also immobilizes TFSI–, thereby enhancing Li+ transport efficiency and contributing to the formation of stable and multifunctional interfaces between electrodes and electrolytes. Consequently, the TPU-TFDMA electrolytes enable the Li symmetric cell to stably work for over 2500 h and endow the LiFePO<inf>4</inf> full cell with a reversible capacity of 130 mAh g–1 after 320 cycles at 0.5 C.
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Hemp-Derived Hierarchical Porous Carbon with an Optimized Pore Structure by NaOH Activation for Supercapacitor Applications
(2025-11-11)
Bowornthommatadsana, Khemjiranee
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Klangvijit, Kanisorn
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Uwanno, Teerayut
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Phonyiem Reilly, Mayuree
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Yordsri, Visittapong
This study focuses on converting hemp hurd, a byproduct of hemp stalk processing, into high-performance activated carbon for supercapacitor applications. Hemp hurd was pyrolyzed and subsequently activated with NaOH at various ratios (biochar:NaOH = 1:1, 1:2, 1:3, 1:4). The Hurd-4 condition (1:4 ratio) yielded the highest specific surface area, 3033 m2/g. Our findings indicate that increasing the chemical activation ratio enhances the mesopore-to-micropore volume ratio (V<inf>meso</inf>/V<inf>micro</inf>) to 1.58 while maintaining a sufficient micropore volume for ion storage. This balanced pore structure effectively increased the specific capacitance, achieving a maximum of 725 F/g at a current density of 0.3 A/g in a 1 M H<inf>2</inf>SO<inf>4</inf>electrolyte. When assembled into a coin cell with an organic electrolyte, Hurd-4 exhibited a maximum specific capacitance of 39 F/g, a maximum energy density of 34 Wh/kg, and a power density of 395 W/kg, surpassing commercial activated carbon. Additionally, the device maintained 78% capacitance retention after 10,000 cycles at a current density of 0.5 A/g. The superior electrochemical properties are attributed to the largest specific surface area, highest pore volume, and optimal mesopore volume ratio. These results demonstrate the potential of hemp hurd as a highly efficient precursor for synthesizing activated carbon for high-performance supercapacitors.
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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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Advanced Water Production via Point of Use Super-Ultralow-Pressure Reverse Osmosis and Cellulose-Polyamide Thin-Film Nanocomposite Membranes
(2025-07-25)
Fajardo-Diaz, Juan Luis
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Martinez-Iniesta, Armando David
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Yamanaka, Ayaka
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Tejima, Syogo
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Izu, Kazou
A novel thin-film nanocomposite reverse osmosis (RO) membrane was developed for point-of-use applications (POU-RO) at super-ultralow pressure (0.2 MPa), incorporating carboxymethylated cellulose nanofibers (CM-CNF). The CM-CNF with an increased number of oxygen-containing functional groups that positively impacts water flux, salt rejection stability, antifouling characteristics, and resistance to chlorine degradation compared to commercial RO-PA membranes. Transmission electron microscopy (TEM), combined with geodesic and skeletonized image analysis, revealed that the average thickness of the PA/CM-CNF membrane is 1050 nm corresponding to more than four leaf-like layers, significantly higher than commercial membranes, which typically show fewer than two layers. Moreover, a void-free active layer is created, providing excellent substrate coverage. Tests with CaCl<inf>2</inf> at 0.2 MPa showed 93.9% salt rejection and a water permeation rate of 0.93 m/d, doubling the performance of commercial membranes. Dynamic simulations confirmed the influence of CM-CNF on enhancing water diffusion at low pressure (0.2 MPa). POU-RO tests, conducted using a 2-inch spiral module fabricated in the laboratory, confirmed the superior performance of the CM-CNF membrane. Indeed, high recovery rates (>60%) and high permeation rates (close to 0.7 m/d) have been achieved by the membranes. This performance is twice than the commercial counterparts tested at 0.2 MPa.
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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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Band gap and photo charge carrier tailoring in zirconium doped carbon nitride using ZrCl4-DMF-melamine for photocatalytic degradation of rhodamine B
(2025-03-05)
Pinming, Chinathun
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Yang, Qingshan
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Kayunkid, Navaphun
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Yordsri, Visittapong
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Wongwiriyapan, Winadda
Improving the performance of carbon nitride (CN) photocatalysts in photocatalytic degradation applications involves optimizing their morphology, electronic properties, and optical characteristics. Zirconium-doped carbon nitride (Zr-doped CN) photocatalysts were synthesized using dimethylformamide (DMF) as a solvent to facilitate the formation of complex molecular structures for effective metal doping. By varying the concentration of the zirconium tetrachloride (ZrCl<inf>4</inf>) precursor between 1 and 3 mmol, we observed significant enhancements in photocatalytic activity. Notably, controlling the ZrCl<inf>4</inf> concentration below 3 mmol prevented the formation of zirconium oxide phases, which could otherwise negatively affect the photocatalytic performance. Zr incorporation led to the morphological transformation of CN from a bulk structure into a hierarchical porous structure, increasing the surface area to 135 m2 g−1. Additionally, Zr doping changed the band energy and electronic properties, creating an optimal energy level for generating oxygen radicals in the photocatalytic water-splitting processes. The photocatalytic degradation of rhodamine B showed that the Zr-doped CN photocatalysts achieved 4.5-fold better performance than undoped CN. Moreover, a small amount of ethylenediaminetetraacetic acid (EDTA) significantly enhanced the photocatalytic efficiency of Zr-doped CN compared to that of undoped CN. These results indicate that combining Zr-doped CN with other materials to create Z-scheme or S-scheme structures could further enhance its performance, thus emphasizing the potential of increasing photocatalytic efficiency by optimizing energy band structures and forming heterostructured photocatalysts.
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Optimizing Electrochemical Performance: A Study of Aqueous Electrolytes with Hemp-Derived Activated Carbon for Supercapacitors
(2025-02-25)
Klangvijit, Kanisorn
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Bowornthommatadsana, Khemjiranee
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Phonyiem Reilly, Mayuree
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Uwanno, Teerayut
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Yordsri, Visittapong
This work investigates the synthesis and electrochemical performance of hemp-derived activated carbon (HAC) for supercapacitor electrode applications. HAC was prepared through NaOH chemical activation, and its electrochemical characteristics were evaluated using three different electrolytes: acidic (H<inf>2</inf>SO<inf>4</inf>), neutral (Na<inf>2</inf>SO<inf>4</inf>), and basic (KOH). The specific surface area of HAC was found to be exceptionally high, measuring 2612 m2/g, surpassing that of commercially available activated carbon (AC). Surface analysis revealed the presence of an oxygen functional group, which provided additional pseudocapacitive active sites. When 1 M H<inf>2</inf>SO<inf>4</inf> was employed as the electrolyte, HAC demonstrated a maximum specific capacitance of 594 F/g (302.4 F/cm3) at a current density of 0.3 A/g. Notably, the HAC electrode exhibited significantly higher energy density and power density, reaching values of 82 Wh/kg (135.7 mWh/cm3) and 188 W/kg (311 mW/cm3), respectively, when compared to commercial AC. These results highlight the potential of HAC as a cost-effective and high-performance electrode material, particularly when paired with H<inf>2</inf>SO<inf>4</inf> as the electrolyte due to their ideal micropore/mesopore ratio for H<inf>2</inf>SO<inf>4</inf> electrolyte access.
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Surface Modification of Activated Carbon by Nitrogen Doping and KOH Activation for Enhanced Carbon Dioxide Adsorption Performance
(2025-01-01)
Chobsilp, Thanattha
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Treetong, Alongkot
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Yordsri, Visittapong
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Santasnachok, Mattana
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Charoeythornkhajhornchai, Pollawat
Nitrogen-doped activated carbon (N-AC) was successfully prepared by KOH-activation and nitrogen doping using ammonia (NH<inf>3</inf>) heat treatment. Coconut shell-derived activated carbon (AC) was heat-treated under NH<inf>3</inf> gas in the temperature range of 700℃–900℃. Likewise, the mixture of potassium hydroxide (KOH) and AC was heated at 800℃, followed by heat treatment under NH<inf>3</inf> gas at 800℃ (hereafter referred to as KOH-N-AC800). Scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) method were utilized to analyze morphology, crystallinity, chemical bonding, chemical composition and surface area. The surface area and porosity of N-AC increased with increasing NH<inf>3</inf> heat treatment. Similarly, the nitrogen content in the N-AC increased from 3.23% to 4.84 at% when the NH<inf>3</inf> heat treatment was raised from 700℃ to 800℃. However, the nitrogen content of N-AC decreased to 3.40 at% after using NH<inf>3</inf> heat treatment at 900℃. The nitrogen content of KOH-N-AC800 is 5.43 at%. KOH-N-AC800 and N-AC800 exhibited improvements of 33.66% and 26.24%, respectively, in CO<inf>2</inf> adsorption compared with AC. The enhancement of CO<inf>2</inf> adsorption of KOH-N-AC800 is attributed to the synergic effect of the nitrogen doping, high surface area, and porosity. The results exhibited that nitrogen sites on the surface play a more significant role in CO<inf>2</inf> adsorption than surface area and porosity. This work proposes the potential synergistic effect of KOH-activation and nitrogen doping for enhancing the CO<inf>2</inf> adsorption capacity of activated carbon.

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