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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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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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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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Preparation of Chitin Nanofibers and Natural Rubber Composites and Their Triboelectric Nanogenerator Applications
(2024-02-01)
Petchnui, Kattaliya
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Uwanno, Teerayut
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Phonyiem Reilly, Mayuree
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Pinming, Chinathun
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Treetong, Alongkot
Triboelectric nanogenerators (TENGs) have gained significant attention as promising energy-harvesting devices that convert mechanical energy into electrical energy through charge separation induced by friction and electrostatic induction. In this study, we explore the utilization of biowaste shrimp shell-extracted chitin nanofiber (ChNF) as a viable eco-friendly material for TENG applications. Composite materials were prepared by incorporating ChNF into natural rubber (NRL) at loading levels of 0.1 and 0.2 wt% (NRL/ChNF) to form the TENG triboelectric layer. ChNFs with a uniform width of approximately 10–20 nm were successfully extracted from the shrimp shells through a simple mechanical procedure. The NRL/ChNF composites exhibited enhanced mechanical properties, as evidenced by a higher Young’s modulus (3.4 GPa) compared to pure NRL. Additionally, the NRL/ChNF composites demonstrated an increased dielectric constant of 3.3 at 0.1 MHz. Moreover, the surface potential difference of NRL increased from 0.182 V to 1.987 V in the NRL/ChNF composite. When employed as the triboelectric layer in TENG, the NRL/ChNF composites exhibited significant improvement in their output voltage, with it reaching 106.04 ± 2.3 V. This enhancement can be attributed to the increased dielectric constant of NRL/ChNF, leading to enhanced charge exchange and charge density. This study presents a straightforward and environmentally friendly technique for preparing sustainable natural materials suitable for energy-harvesting devices.
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Control of Manganese Oxide Hybrid Structure through Electrodeposition and SILAR Techniques for Supercapacitor Electrode Applications
(2023-08-01)
Klangvijit, Kanisorn
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Wongwiriyapan, Winadda
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Uwanno, Teerayut
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Obata, Michiko
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Fujishige, Masatsugu
Manganese oxide has been studied as a promising supercapacitor electrode due to its high theoretical capacitance, low cost, and environmental friendliness. Supercapacitor performance such as specific capacitance, resistance, and cycle life greatly depends on the morphology and crystal structure of manganese oxide. In this study, a Mn<inf>3</inf>O<inf>4</inf> hybrid structure was successfully synthesized using electrodeposition and successive ionic layer adsorption and reaction (SILAR) techniques which are simple, cost-effective, and low-temperature wet chemical processes. It was found that Mn<inf>3</inf>O<inf>4</inf> morphology is different depending on manganese precursors and synthesis techniques. Sea-grape-like and bird nest-like morphologies were obtained via the electrodeposition technique, while flower-like and nanoparticle morphologies were formed via the SILAR technique using manganese acetate and manganese sulfate as precursors, respectively. The hybrid structure of the nanoparticle-decorated bird nest-like heterostructure was prepared using manganese sulfate electrodeposition and subsequent SILAR deposition of manganese acetate. X-ray photoelectron spectroscopy confirmed the Mn<inf>3</inf>O<inf>4</inf> formation. Electrochemical properties of manganese oxide hybrid structure were systematically studied with cyclic voltammetry and galvanostatic charge–discharge, showing the highest areal capacitance of 390 mF cm−2 at 0.1 mA cm−2 with series and charge transfer resistances down to 4.55 and 4.91 Ω in 1 M sodium sulfate electrolyte.
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Electrically Inert h-BN/Bilayer Graphene Interface in All-Two-Dimensional Heterostructure Field Effect Transistors
(2018-08-29)
Uwanno, Teerayut
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Taniguchi, Takashi
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Watanabe, Kenji
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Nagashio, Kosuke
Bilayer graphene field effect transistors (BLG-FETs), unlike conventional semiconductors, are greatly sensitive to potential fluctuations because of the charged impurities in high-k gate stacks because the potential difference between two layers induced by the external perpendicular electrical filed is the physical origin behind the band gap opening. The assembly of BLG with layered h-BN insulators into a van der Waals heterostructure has been widely recognized to achieve the superior electrical transport properties. However, the carrier response properties at the h-BN/BLG heterointerface, which control the device performance, have not yet been revealed because of the inevitably large parasitic capacitance. In this study, the significant reduction of potential fluctuations to ∼1 meV is achieved in an all-two-dimensional heterostructure BLG-FET on a quartz substrate, which results in the suppression of the off-current to the measurement limit at a small band gap of ∼90 meV at 20 K. By capacitance measurement, we demonstrate that the electron trap/detrap response at such heterointerface is suppressed to undetectable level in the measurement frequency range. The electrically inert van der Waals heterointerface paves the way for the realization of future BLG electronics applications.

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