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Electrolytic exfoliation of few-layer graphene/sodium dodecylbenzenesulfonate for coin- and cylindrical-cell supercapacitor electrodes
(2023-06-01)
Lomas, Tanom
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Poochai, Chatwarin
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Sukjit, Peemases
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Wasapinyokul, Kamol
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Mensing, Johannes P.
Electrolytic exfoliation of graphite is a promising way to produce graphene quickly, inexpensively, and in an environmentally friendly manner. In this research, sodium dodecylbenzenesulfonate (SDBS), a commonly used anionic surfactant, was dissolved in 1 M H<inf>2</inf>SO<inf>4</inf> to produce SDBS-graphene via electrolytic graphite exfoliation. The AFM analysis validated the thickness of few-layer of SDBS-graphene between 5 and 15 nm. Then, a symmetric coin-cell (CR2032) supercapacitor (SC) comprised of SDBS-graphene and rGO (synthesized via Hummer's method) was assembled with 0.5 M H<inf>2</inf>SO<inf>4</inf> as an electrolyte. The highly exfoliated SDBS-graphene demonstrated a greater capacitive electrochemical response than rGO. The CV and GCD techniques revealed that the specific capacitance of SDBS-graphene was 150 F g−1 at 0.25 A g−1 with 20.4 Wh kg−1 of energy density and 494 W kg−1 of power density and that its percentage capacitive retention remained 95 % after 10,000 cycles at 3 A g−1, compared to the specific capacitance of reduced graphene. In addition, a cylindrical cell SC (CR32650) with SDBS-graphene demonstrated a capacitance of 220 F at 100 mA, along with an energy density of 33 kWh and a power density of 55 kW. This suggests that exfoliated SDBS-graphene may be utilized in SCs with high efficiency and long-term durability.
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A Novel Synthesis of Rod-Shape BaNiSn-Graphene Decorated TiO2 Composite as a Ternary Photocatalyst to Improve Visible-Light Driven H2 Evolution with Lactic Acid and TEA
(2023-03-01)
Areerob, Yonrapach
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Rafat, Md Nazmodduha
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Ullah, Kefayat
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Oh, Won Chun
A novel rod-shape BaNiSn-Graphene oxide decorated TiO<inf>2</inf> composite (BaNiSn-GT) has been synthesized using a simple ultrasonic method to enhance the visible-light-driven H<inf>2</inf> evolution with cationic scavengers. The unique structure between the interfaces of BaNiSn-Graphene and TiO<inf>2</inf> provides graphene oxide of contact and excellent electron transfer for H<inf>2</inf> evolution activity. The BaNiSn-GT ternary photocatalyst exhibits relatively high photocatalytic activity with a hydrogen evolution rate of 1012 μmol/g during 4 h. On the other hand, BaNiSn-GT composite exhibited significantly higher hydrogen evolution rates of 870 μmol/g with TEA scavenger and 730 μmol/g with LA scavenger during 1 h, respectively. Moreover, the higher photocurrent density of BaNiSn-GT is correlated with electron–hole recombination, providing evidence for its inhibition, which leads to a longer lifetime of carriers produced by photoelectrons. The mechanism of the photocatalytic H<inf>2</inf> evolution of BaNiSn-GT based on a full physicochemical characterization was proposed. This study provides new insight into the efficient hydrogen-evolution of graphene-based photocatalysts.
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Anti-corrosion performance of vinyl ester resin films with titanium dioxide and graphene hybrid reinforcement
(2022-12-01)
Khamme, Eakapoj
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Sakulkalavek, Aparporn
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Sakdanuphab, Rachsak
The present investigation addresses the development of vinyl ester resin (VER) by exfoliating titanium dioxide (TiO<inf>2</inf>) and graphene (G) in polymeric resin for anticorrosion applications on carbon steel (CS) substrates with different additive fillers (TiO<inf>2</inf> 3 wt%, G 2 wt%, and TiO<inf>2</inf> 3 wt% + G 2 wt%). The purpose of the study was to investigate structure, chemical bonding, adhesion, and corrosion. VER was prepared by triggering methyl ethyl ketone peroxide (MEKP) and an accelerator of cobalt naphthalate. The dip-coating method of VER composite films was fabricated on CS substrate with film thicknesses between 70 and 100 µm. The additive-polymer chemical bonding, morphologies and microstructure have been analysed by the techniques of Fourier transform infra-red spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). Electrochemical impedance spectroscopy (EIS) and adhesion test were used to examine the anti-corrosion behaviour and performance. The blending of the additive fillers led to cobalt dispersion, crystallinity and corrosion resistance due to the development of interpenetrating polymer networks (IPNs) inside the VER films. TiO<inf>2</inf> and G hybrid reinforcements in VER enhance corrosion resistance and film adhesion.
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Graphene addition improved figure of merit in SnTe prepared by the rapid hybrid microwave solid-state method
(2022-02-01)
Gobpant, Jakrit
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Somdock, Nuttakrit
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Limsuwan, Pichet
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Sakulkalavek, Aparporn
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Sakdanuphab, Rachsak
We successfully synthesised SnTe-based powders (SnTe, Sn<inf>0.95</inf>Bi<inf>0.05</inf>Te, and SnTe with graphene addition) by a hybrid microwave solid-state method. This demonstrated comparable thermoelectric performance to the conventional heating method but had low energy consumption and rapid synthesis. Graphene addition to SnTe materials resulted in significant reduction of thermal conductivity. The SnTe with 5 wt% graphene exhibited a reduction in overall thermal conductivity from ∼10 W m−1 K−1 for SnTe to ∼2 W m−1 K−1 at 325 K and showed a moderate power factor. The Debye model was used to explain the origin of the effects of graphene on lattice thermal conductivity. The dimensionless figure of merit was increased by five times, from 0.07 for SnTe to 0.35 for SnTe with 5 wt% graphene. Our results demonstrated an effective method and additive material to synthesise and enhance the thermoelectric properties of SnTe materials.
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Fe2O3-graphene anchored Ag nanocomposite catalyst for enhanced sonocatalytic degradation of methylene blue
(2021-05-01)
Noypha, Amnuay
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Areerob, Yonrapach
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Chanthai, Saksit
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Nuengmatcha, Prawit
In the present research work, Fe<inf>2</inf>O<inf>3</inf>-graphene-Ag (FGA) was synthesized by a simple hydrothermal method. The sonocatalytic activity of the FGA particles was evaluated by the degradation of methylene blue (MB) under ultrasonic irradiation, revealing their good sonocatalytic activity. The effects of various experimental factors, such as dosage, time, and ultrasonic frequencies on the sonocatalytic efficiency were investigated; a significant influence of different factors on the sonocatalytic degradation of MB was observed, whereas the best degradation conditions were obtained when ultrasonic irradiation was performed for 90 min at room temperature considering MB concentration = 0.5 g L−1, C<inf>catalyts</inf> = 1 g L−1, and pH 6.5. Moreover, the sonocatalytic activity of the FGA was compared to that of Fe<inf>2</inf>O<inf>3</inf> (F), graphene (G), and Fe<inf>2</inf>O<inf>3</inf>-graphene (FG). As a result, the FGA was found to exhibit higher sonocatalytic activity than other catalysts (FGA > FG > G > F), which evidenced the practical utility of the synthesized FGA as a highly effective catalyst for the removal of dye pollutants. Finally, the plausible sonocatalytic mechanism of FGA is also discussed in this work.
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Contact Angle Measurement of Melting SnAgCu Solder Paste Mix with Carbon Allotropes Using In-Line Digital Holography Technique
(2021-01-01)
Mamart, Wikatsama
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Somdock, Nuttakrit
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Boonsri, Chantira
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Plaipichit, Suwan
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Buranasiri, Prathan
In this research we investigated the contact angle of commercial SnAgCu solder paste mixing with some carbon allotropes such as graphite, graphene quantum dots, and fullerene of varying concentrations with melting temperature, wettability, interfacial microstructure. The wettability was assessed in terms of the contact angle. The in-line digital holography was used for determining the contact angle and morphological of samples at each temperature which the samples have been heating from room temperature until the melting temperature. In the experiment, only one beam was used as the object and reference beams which recorded by a CMOS camera. The recorded image was reconstructed by the angular spectrum digital holography numerical programing. Using the reconstructed images of our results, the shape and contact angle of solder pastes can be investigated.
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Figure of merit improvement of delafossite CuAlO2 with the addition of Fe and graphene
(2019-11-01)
Daichakomphu, Noppanut
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Harnwunggmoung, Adul
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Chanlek, Narong
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Sakdanuphab, Rachsak
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Sakulkalavek, Aparporn
This study investigated the synthesis of delafossite CuAlO<inf>2</inf> with Fe and graphene through a solid-state reaction method. The results of X-ray diffractometry showed that graphene was insoluble in delafossite CuAlO<inf>2</inf> while Fe was substituted into Al sites, expanding the d-spacing. From X-ray photoelectron spectroscopy, graphene induced excess oxygen in the delafossite CuAlO<inf>2</inf> structure via C–O–Cu bonds and improved the electrical conductivity. In addition, the thermal conductivity was reduced due to generation of point defects, phonon-phonon Umklapp and carrier-phonon scattering. The addition of Fe and graphene in CuAlO<inf>2</inf> shows an improvement of ZT to 0.0114 at 573 K. This is attributable to its increase in charge carrier density, as well as a decrease in thermal conductivity. This study highlights the benefits of combining Fe and graphene in delafossite CuAlO<inf>2</inf> as a prospective process for attaining a high figure of merit thermoelectric materials.
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A Screen Printed Graphene Based Electrochemical Sensor for Single Drop Analysis of Hydroquinone in Cosmetic Products
(2019-08-01)
Duekhuntod, Wannida
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Karuwan, Chanpen
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Tuantranont, Adisorn
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Nacapricha, Duangjai
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Teerasong, Saowapak
A graphene modified carbon paste sensor (or so-called graphene based sensor) was developed for electrochemical detection of hydroquinone. The sensor was fast fabricated using screen-printing technique. By integrating three fundamental electrodes on a single device, the sensor is small and portable. A determination is based on a one drop analysis. A 60 μ.L-drop of sample was placed onto the sensor prior to cyclic voltammetric measurement. The method relies on green analysis since it lowers the consumption of sample and waste generation. Under the optimal conditions, a linear calibration was achieved in range of 1.0 x 10-4 to 5.0 x 10-3 M hydroquinone. The detection limit was 7 x 10-5 M, a sensitive adequate for measuring hydroquinone in cosmetic products. The sensor provided good precision (%RSD = 2.78) and accuracy (recoveries = 87-114%), with analysis times of less than a minute. The sensor was applied to determine the presence of hydroquinone in whitening creams. The results obtained from the developed sensor satisfactorily agreed with the HPLC method, indicating the reliability of the method. Due to its advantages in terms of rapidity, low-cost and portability, the device is a viable choice for on-site screening for hydroquinone contamination in whitening products.
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Achieving thermoelectric improvement through the addition of a small amount of graphene to CuAlO2 synthesized by solid-state reaction
(2018-07-15)
Daichakomphu, Noppanut
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Sakdanuphab, Rachsak
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Harnwunggmoung, Adul
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Pinitsoontorn, Supree
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Sakulkalavek, Aparporn
In this work, delafossite CuAlO<inf>2</inf> powders with graphene (0.00–0.20 wt%) were synthesized by a solid-state reaction method. X-ray diffraction and transmission electron microscope results indicated that graphene was segregated in CuAlO<inf>2</inf> as a split phase, such as composite material. A little addition of graphene content reduces the thermal conductivity and increases the carrier concentration because the graphene generates many point defects and aided carrier-phonon scattering. The CuAlO<inf>2</inf> with graphene content of 0.05 wt% shows the maximum electrical conductivity of 470 S/m at 700 K. In addition, the maximum value for ZT of 0.0045 was recorded at 575 K with the graphene/CuAlO<inf>2</inf> composite (0.05 wt%). Therefore, in brief, this study has highlighted the benefits of combining delafossite CuAlO<inf>2</inf> with a small amount of graphene as a potential route for achieving highly efficient thermoelectric materials.
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Hybrid graphene and poly(methyl methacrylate) for gas sensor application
(2017-01-01)
Rattanabut, Chanoknan
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Muangrat, Worawut
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Phonyiem, Mayuree
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Bungjongpru, Win
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Wongwiriyapan, Winadda
The graphene and hybrid graphene/poly(methy methacrylate) (PMMA) were fabricated for use in volatile organic compound (VOC) detection. Graphene was synthesized on copper foil by chemical vapor deposition (CVD). To remove Cu foil, PMMA was coated on graphene by spin-coating (hereafter referred to as graphene/PMMA) and transferred to silicon substrate with silicon dioxide layer (SiO<inf>2</inf>/Si) by wetting transfer process. For comparison, a PMMA layer was removed in order to achieve a pristine graphene. Graphene and hybrid graphene/PMMA sensors showed the highest sensor response to ethanol. Responses of the graphene to ethanol, dichloromethane and benzene were 5.62, 20.06 and 35.09 times higher than that of hybrid graphene/PMMA. The sensor response of graphene can be described in terms of the dielectric constant of VOC. In addition, the sensor response of hybrid graphene/PMMA to benzene and dichloromethane would be attributed to the Hansen solubility parameter (HSP), while that of ethanol is related to the molecular size. These results suggest that the integration of graphene with PMMA is a promising approach for the selectivity for VOC detection.

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