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Physical feature exploration of nanocrystalline FeSi2 surface with argon plasma etching under varying power
(2023-12-01)
Borwornpornmetee, Nattakorn
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Sittimart, Phongsaphak
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Phatthanakun, Rungrueang
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Nakajima, Hideki
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Paosawatyanyong, Boonchoat
Nanocrystalline (NC) FeSi<inf>2</inf> films were created on Si(111) wafers via direct-current sputtering with facing targets at an ambient temperature, then the films were etched by Ar plasma generated through microwave source at different powers of 50, 100, and 150 W. The surface morphology of the as-coated NC FeSi<inf>2</inf> films showed numerous small uniform crystallites and root-mean-square roughness of 4.65 Å. The surface for each etched NC FeSi<inf>2</inf> film showed appearance of holes and slight increase in the roughness as the power increased. X-ray photoelectron spectra showed that the etching decreased the content of hydrophobic carbon and increased the presence of polar oxide group on the NC FeSi<inf>2</inf> films as the power increased. These changes should be the factor behind the shift from hydrophobic state to hydrophilic state. The contact angle of the unetched NC FeSi<inf>2</inf> film surface was 100.55°, which is hydrophobic. The NC FeSi<inf>2</inf> film's surface reached a minimum contact angle of 35.65°, which belong to hydrophilic state, when the etching power was increased to 150 W. The mechanical properties of NC FeSi<inf>2</inf> films rarely affect by Ar plasma. The change in surface state to nearly superhydrophilic after plasma etching indicate possibility to develop NC FeSi<inf>2</inf> into a self-cleaning surface coating material.
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Effect of Surface Modification on Corrosion Resistance, Mechanical and Electrical Properties of Epoxy Resin-Based Nanocomposites
(2023-01-01)
Buaphuen, Phummiphat
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Tongpon, Pattaraton
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Vittayakorn, Wanwilai
The epoxy resin-based nanocomposites have been used to overcome the drawback of epoxy resin such as brittle, low impact resistance, poor stress cracking and poor corrosion resistance in the aggressive environment by incorporating inorganic nanoparticles into the high cross-linked structure of epoxy resin. However, the main problem of these composites is the agglomeration of nanoparticles which influences the worst dispersion in the epoxy matrix and leads to poor properties of the composite. Therefore, this work aims to study the effect of nanoparticle additions, i.e. ZrO<inf>2</inf> nanoparticle and SiO<inf>2</inf> nanoparticle including waste glass powder (WGP) which is an alternative inorganic filler, on properties of the epoxy resin-based nanocomposite. The particle surface of each filler was also modified with 3-glycidoxypropyltrimethoxysilane (GTPMS) in order to achieve better dispersion in the disk-shaped bulk composites. The chemical property of modified fillers was characterized by Fourier transform infrared spectroscopy (FT-IR). The physical properties, mechanical properties, water absorption and corrosion resistance of all composites are then investigated. The results revealed that the incorporations of ZrO<inf>2</inf>, SiO<inf>2</inf>, and WGP with GPTMS surface modification into epoxy resin-based nanocomposite exhibit better performance in mechanical properties, water absorption and corrosion resistance than the unmodified surface of ZrO<inf>2</inf>, SiO<inf>2</inf>, and WGP additions. Although, both modified- and unmodified surfaces of fillers for the epoxy resin-based nanocomposites show improvement in all properties compared to the neat epoxy resin but the electrical properties of epoxy resin-based nanocomposites with unmodified fillers and GPTMS-modified fillers do not show a significant effect on any electrical properties.
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Ultrasonically assisted surface modified CeO2 nanospindle catalysts for conversion of CO2 and methanol to DMC
(2022-11-01)
Kulthananat, Tachatad
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Kim-Lohsoontorn, Pattaraporn
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Seeharaj, Panpailin
This study developed a facile and effective approach to engineer the surface properties of cerium oxide (CeO<inf>2</inf>) nanospindle catalysts for the direct synthesis of dimethyl carbonate (DMC) from CO<inf>2</inf> and methanol. CeO<inf>2</inf> nanospindles were first prepared by a simple precipitation method followed by wet chemical redox etching with sodium borohydride (NaBH<inf>4</inf>) under high intensity ultrasonication (ultrasonic horn, 20 kHz, 150 W/cm2). The ultrasonically assisted surface modification of the CeO<inf>2</inf> nanospindles in NaBH<inf>4</inf> led to particle collisions and surface reduction that resulted in an increase in the number of surface-active sites of exposed Ce3+ and oxygen vacancies. The surface modified CeO<inf>2</inf> nanospindles showed an improvement of catalytic activity for DMC formation, yielding 17.90 mmol·g<inf>cat</inf>−1 with 100 % DMC selectivity. This study offers a simple and effective method to modify a CeO<inf>2</inf> surface, and it can further be applied for other chemical activities.
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Surface modification of PEDOT: PSS film by chemical vapor texturing process for enhanced organic photovoltaics
(2020-12-01)
Ritruksa, Mantarat
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Wongrerkdee, Sawitree
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Lohawet, Khathawut
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Kaewprajak, Anusit
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Kumnorkaew, Pisist
Surface modification of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) film was performed using chemical vapor texturing process of HNO<inf>3</inf> vapor. Textured PEDOT:PSS film exhibits higher root-mean-square roughness of 14.43 nm than pristine PEDOT:PSS film of 11.87 nm with small decrease in thickness. Moreover, approximate one-half reduction of sheet resistance is measured. In correspondence with roughness, increasing optical transmittance in the visible region and reducing water contact angle are explored. The reduction of water contact angle implies that active layer can be deposited on the textured film with better coverage to improve interfacial contact for OPV fabricating process. This improvement facilitates charge transfer in OPV device which causes the increase of short-circuit current density (J<inf>sc</inf>) from 7.42 mA/cm2 to 8.01 mA/cm2. The increased J<inf>sc</inf> is the major photovoltaic parameter in OPV enhancement. Therefore, the PEDOT:PSS film textured with the chemical vapor texturing process is demonstrated as an efficient rough film for OPV enhancement. Furthermore, the rough film modified using the process could be suggested for applying in several thin-film based devices.
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Microcorona Discharge-Mediated Nonthermal Atmospheric Plasma for Seed Surface Modification
(2018-07-01)
Teerakawanich, Nithiphat
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Kasemsuwan, Varakorn
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Jitkajornwanich, Kulsawasd
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Kanokbannakorn, Weerawoot
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Srisonphan, Siwapon
By exploiting the physical effect of a highly nonuniform localized electric field and electron-initiated impact ionization on space charge, we generated homogeneous nonthermal plasma under ambient atmosphere. We evaluated the physical characteristics and evolution of microcorona discharge-induced nonthermal atmospheric plasma (NAP) based on a point-to-plane electrode in open air with two distinct configurations. High-voltage pulses were employed as the primary power source of corona discharge generation to reveal the fundamental mechanism, polarity effect and feasibility of using NAP for organic surface modification. Consequently, we employed NAP to modify the surface of rice (Oryza sativa L.) seeds to improve their wettability. The surface modification of the rice seeds was investigated via water apparent contact angle (ACA) and water imbibition (WI) measurements. The ACA and WI measurements revealed not only the improvement in the wetting properties but also the mutual relationships between and limitations of ACA and WI analysis. We found that the WI time reached saturation after a certain treatment time, called the threshold treatment time. Because vacuum conditions are not required, well-established NAP technology will garner interest in many fields, ranging from the life, environmental, and biomedical sciences to solid-state electronics applications.
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Development and surface modification of anion exchange membrane for enhancement of antifouling potential in electrodialys process
(2018-01-01)
Khan, Muhammad Imran
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Zafar, Shagufta
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Khraisheh, Majeda
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Khan, Muhammad Ali
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Buzdar, Abdul Rehman
The membrane fouling in the course of electrodialysis (ED) is a serious problem during water treatment which results to its shorter lifetime and higher energy consumption. Here, the antifouling property of previously reported BPPO-based anion exchange membranes (AEM) has been improved by surface coating with polydopamine (PDA). The modified and unmodified membranes were characterized in term of Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) water contact angle and water uptake. The antifouling potential was investigated in term of transition time, i.e. the time elapsed before the fouling took place.
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Surface modification of TiO2 particles with the sono-assisted exfoliation method
(2017-11-01)
Thasirisap, Eakkasit
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Vittayakorn, Naratip
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Seeharaj, Panpailin
This study reported a novel approach to optimize the photocatalytic property of anatase TiO<inf>2</inf> particles by delaminating their outer surface into highly reactive nanosheets via the sono-assisted exfoliation method. To modify the surface, TiO<inf>2</inf> particles were dispersed in aqueous solution of 10 M sodium hydroxide (NaOH) and tetrabutylammonium hydroxide (TBAOH), followed by irradiation with high intensity ultrasonic wave (20 kHz, 150 W/cm2) for 60 min. The intercalation and exfoliation processes were accelerated with the driving force of the extreme acoustic cavitation leading to the delamination of TiO<inf>2</inf> nanosheets with highly reactive exposed {0 0 1} facets from the mother TiO<inf>2</inf> crystals. The presence of TBAOH increased yield of nanosheets formation and stabilized the nanosheet structure. The unique morphology of the surface modified TiO<inf>2</inf> particles provided benefits in increasing the specific surface area and lowering the optical band gap energy (E<inf>g</inf>) and electron-hole recombination rate resulting in an enhancement of methylene blue dye degradation efficiency. The surface modification of TiO<inf>2</inf> particles by the sono-assisted exfoliation method can optimize the photocatalytic activity by yielding synergetic effects of the high surface reactive sites of the nanosheets and the high degree of crystallinity of the bulk structure.
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Polarity effect of pulsed corona discharge plasma on seed surface modification
(2017-10-19)
Bunme, Pawita
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Khamsen, Natthaporn
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Kasemsuwan, Varakorn
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Jitkajornwanich, Kulsawasd
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Pichetjamroen, Achara
This paper presents an experimental analysis and underlying mechanism of positive and negative pulsed corona discharge induced atmospheric non-Thermal plasma. We designed a system based on point-plane configuration to produce direct corona discharge plasma (DCP) and hybrid corona discharge plasma (HCP) systems. The polarity effect of corona discharge for surface modification application on rice seeds was investigated under atmospheric dry air ambient. The reactive species under negative and positive corona discharge plasma were also studied for optimization design. The results show that only negative pulsed corona discharge is feasible for DCP system while both positive and negative pulsed corona discharge can be employed for in HCP system.
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Durable nitrate sensor by surface modification
(2016-11-25)
Chaisriratanakul, W.
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Bunjongpru, W.
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Jeamsaksiri, W.
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Srisuwan, A.
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Porntheeraphat, S.
This work presents the development of nitrate sensor based on Ion Sensitive Field Effect Transistor (ISFET) technology to achieve longer device's lifetime. This lifetime depended on the adhesion of PVC ion-selective membrane on the Si<inf>3</inf>N<inf>4</inf> sensing membrane of ISFET. The adhesion level directly affected the leaching of plasticizer. Such improvement utilized surface modification techniques by immersing the sensing membrane in the solution of 5% 3-mercaptopropyl-trimethoxysilane (MPTMS)/methanol. The modified surface was detected through the change of hydrophobicity and thickness of MPTMS using the contact angle measurement and ellipsometry techniques. The appropriate time for immersion was 18 h. The modified surface achieved the optimal hydrophobicity with contact angle of 100.32°. The presence of MPTMS film was confirmed by detecting the thiol-group using Fourier Transform Infrared (FTIR) spectrophotometry and Auger Electron Spectroscopy (AES). The PVC ion-selective membrane was then immobilized on the surface to create nitrate sensors with the following characteristics. The Nitrate-Nitrogen detection limit = 2.44 ppm with linear range from 5 to 60 ppm at sensitivity of 56 mV/dec. (R2 = 1). The response time was 90 s. Finally, this nitrate sensor could extend the total utilization lifetime from 8 to 17 weeks.
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Efficiency of SPIONs functionalized with polyethylene glycol bis(amine) for heavy metal removal
(2016-09-15)
Wanna, Yongyuth
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Chindaduang, Anon
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Tumcharern, Gamolwan
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Phromyothin, Darinee
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Porntheerapat, Supanit
Hybrid magnetic nanoparticles based on poly(methylmethacrylate) (PMMA) and super-paramagnetic iron oxide nanopaticles (SPIONs) with selective surface modification has been developed for heavy metal removal by applying external magnetic fields. The nanoparticles were prepared by the emulsion polymerization technique in an aqueous suspension of SPIONs. The hydrolysis of carboxyl functional group was then applied for grafting polyethylene glycol bis(amine)(PEG-bis(amine)) onto the PMMA-coated SPIONs. The morphology, the chemical structure and the magnetic properties of the grafted nanoparticles were investigated. The efficiency of the hybrid nanoparticles for heavy metal removal were conducted on Pb(II), Hg(II), Cu(II) and Co(II) in aqueous solutions.The metal concentration in the solutions after separation by the hybrid nanoparticles was determined by inductively coupled plasma optical emission spectrometer (ICP-OES). The results show the heavy metal uptake ratios of 0.08, 0.04, 0.03, and 0.01 mM per gramme of the grafted SPIONs for Pb(II), Hg(II), Cu(II), and Co(II), respectively. A competitive removal of Cu(II), Pb(II), Co(II) and Hg(II) ions in mixed metal salt solutions has also been studied.The heavy metal removal efficiency of the hybrid nanoparitcles was found to depend on the cation radius, in accordance with capture of metal ions by the amine group.

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