Go Kawamura | Toyohashi University Of Technology (original) (raw)
Papers by Go Kawamura
Formation of grassy TiO2 nanotube thin film by anodisation in peroxide electrolyte for Cr(VI) removal under ultraviolet radiation
Nanotechnology
Honeycomb-like open-edged reduced-graphene-oxide-enclosed transition metal oxides (NiO/Co3O4) as improved electrode materials for high-performance supercapacitor
Journal of Energy Storage
Fe3O4-embedded rGO composites as anode for rechargeable FeOx-air batteries
Materials Today Communications
Comparison of ZrO2, TiO2, and α-Fe2O3 nanotube arrays on Cr(VI) photoreduction fabricated by anodization of Zr, Ti, and Fe foils
Materials Research Express
Parameters and Underlying Mechanisms Affecting the Morphology of Bifurcating TiO2 Nanotube
ECS Meeting Abstracts
Nanomaterials
Micro/nanoscale design of composite materials enables alteration of their properties for advanced... more Micro/nanoscale design of composite materials enables alteration of their properties for advanced functional materials. One of the biggest challenges in material design is the controlled decoration of composite materials with the desired functional additives. This study reports on and demonstrates the homogeneous decoration of hexagonal boron nitride (hBN) on poly(methylmethacrylate) (PMMA) and vice versa. The formation of the composite materials was conducted via a low environmental load and a low-energy-consuming, electrostatic nano-assembly method which also enabled the efficient usage of nano-sized additives. The hBN/PMMA and PMMA/hBN composites were fabricated in various size combinations that exhibited percolated and layer-oriented structures, respectively. The thermal conductivity behaviors of hBN/PMMA and PMMA/hBN composites that exhibited good microstructure were compared. The results showed that microstructural design of the composites enabled the modification of their hea...
Synthesis of mesoporous Co(OH)2 nanostructure film via electrochemical deposition using lyotropic liquid crystal template as improved electrode materials for supercapacitors application
Journal of Electroanalytical Chemistry
Nanoscale Research Letters
This work reports on a novel controlled nanocomposite fabrication technique which is applicable f... more This work reports on a novel controlled nanocomposite fabrication technique which is applicable for material design via a micro-and nano-assembly method. The principle is based on the use of electrostatic adsorption of the surface charge-modified particles via layer-by-layer assembly. The polarity and the zeta potential of the surface charge was controlled using polycation and polyanion, while the zeta potential strength was controlled via the number of alternating coating layers which was determined using zeta potential measurement. A systematic study was conducted to demonstrate the feasibility of composite material assembly via electrostatic adsorption using alumina (Al 2 O 3 ) and silica (SiO 2 ) composite as a study model, which was carried out as a function of surface zeta potential, surface coverage percentage, and processing time. The considerable potential of this technique for composite material design is also further demonstrated with controlled assembly involving different materials in various structural forms such as fiber, whisker, nanosheets, and even irregular-shaped foam-like structured urethane. The composite materials designed using this EA method possess good potentials to be utilized for various applications such as mechanical property control, composite ceramic films formation, selective laser sintering, and rechargeable metal-air battery.
Nanomaterials
Formation of functional composite materials with desired properties is important for advanced app... more Formation of functional composite materials with desired properties is important for advanced application development. However, formation of a homogenous composite material via conventional mixing methods still remains a challenge due to agglomeration. Therefore, this work reports and demonstrates the formation of a homogeneous poly(methylmethacrylate) (PMMA)-indium tin oxide (ITO) composite with high visible light transparency (up to 90%) with an excellent shielding effect of infra-red (IR) via a facile electrostatic assembly method. This PMMA-ITO composite with good transparency and an IR shielding effect has good potential to be used in the automobile industry for vehicle windscreens as well as in heat preservation or preventive technology. The IR shielding rate is demonstrated to be controllable by changing the amount of ITO nanoparticles additive. This finding would provide a platform for development of IR optical related polymeric composite materials.
Anhydrous proton conductive xCHS-(1-x)WSiA composites prepared via liquid-phase shaking
Solid State Ionics
Science and Technology of Advanced Materials
We report a novel and inexpensive fabrication process of multiferroic nanocomposite via liquid ph... more We report a novel and inexpensive fabrication process of multiferroic nanocomposite via liquid phase using an anodic alumina template. The sol-gel spin-coating technique was used to coat the template with ferrimagnetic CoFe 2 O 4 . By dissolving the template with NaOH aqueous solution, a unique nanotube array structure of CoFe 2 O 4 was obtained. The CoFe 2 O 4 nanotube arrays were filled with, and sandwiched in, ferroelectric BaTiO 3 layers by a sol-gel spin-coating method to obtain the composite. Its multiferroicity was confirmed by measuring the magnetic and dielectric hysteresis loops.
Investigation of the anchor layer formation on different substrates and its feasibility for optical properties control by aerosol deposition
Applied Surface Science
E3S Web of Conferences
Inorganic-organic composite membranes were prepared by using partly cesium-substituted silicotung... more Inorganic-organic composite membranes were prepared by using partly cesium-substituted silicotungstic acid (CHS-WSiA) and polybenzimidazole (PBI, MRS0810H) for medium temperature polymer electrolyte fuel cells (MT-PEFCs). Cesium hydrogen sulfate (CsHSO4, CHS) and silicotungstic acid (H4SiW12O40, WSiA) were milled to obtain 0.5CHS-0.5WSiA composites by dry and wet mechanical millings. N,Ndimethylacetamide (DMAc) was used as a disperse medium in the preparation of the inorganic solid acids by wet mechanical milling and also a casting agent for fabrication of membrane. Finally, flexible and homogeneous composite membranes with several phosphoric acid doping levels (PADLs) were obtained. The wet mechanical milling using DMAc was found to effectively promote good substitution of H+ ion in WSiA by Cs+ ion of CHS and promoted the formation of smaller grain sizes of composites, compared with dry milling. A high maximum power density of 378 mWcm-2 and a good constant current stability test w...
Sol-gel template synthesis of BaTiO3 films with nano-periodic structures
Materials Letters
Journal of the Ceramic Society of Japan
Demand for low-cost, environmentally friendly alternative renewable energy sources makes the dye-... more Demand for low-cost, environmentally friendly alternative renewable energy sources makes the dye-sensitized solar cell (DSSC) a viable alternative. DSSCs have a high but competitively challenged power conversion efficiency (PCE) of 11.9%. Plasmonic DSSCs is one approach with extreme enhancement of light absorption to increasing the PCE. The highest PCE of plasmonic DSSCs is still <11% however, due to secondary effects which are not yet well understood. In this study, we used a complex composite of plasmonic nanoparticles (PNPs) with extended characterization and wide ranging PNP loadings, combined with a systematic approach to obtain synergistic effects and a deeper understanding of the effects of plasmonic nanostructures on DSSC performance. The results showed two optimal loading amounts of PNPs with enhanced PCEs of 4.26 and 4.36% (from 3.54%), with enhancement effects obtained mainly from efficient charge injection and a balance of the negative and positive effects of the PNPs, respectively. An increase in the photoanode thickness from 5.5 to 9¯m resulted in PCE enhancement from 4.39 to 4.58%, mainly via efficient charge injection. The PNPs had both positive and negative effects on key DSSC performance parameters: decreased photoanode surface area but with panchromatic enhancement of light absorbance; increased short circuit current up to a point followed by a decrease due to poor charge injection; increased open circuit voltage and fill factor; enhanced charge transfer resistance against charge recombination; improved electron lifetime and charge collection efficiency; lowered enhancement of cell performance in the near infra-red region; and induced abundantly generated electrons augmented charge recombination. These results contribute significantly to understanding of the effects of plasmonic nanostructures and can serve as a useful guide to the study of plasmonic DSSCs and related fields.
Annealing temperature-dependent crystallinity and photocurrent response of anodic nanoporous iron oxide film
Journal of Materials Research
Fabrication of biosensor based on Chitosan-ZnO/Polypyrrole nanocomposite modified carbon paste electrode for electroanalytical application
Materials Science and Engineering: C
A sensitive conductive nanocomposite sensor consisting of chitosan, zinc oxide nanoparticles, and... more A sensitive conductive nanocomposite sensor consisting of chitosan, zinc oxide nanoparticles, and polypyrrole was developed. The sensor was prepared by oxidative polymerization of pyrrole using (NH4)2S2O8 as the oxidant followed by mixing a Chitosan-Zinc oxide composite with a different content of Chitosan. The morphology and surface area of the nanocomposites were changed by changing the percentage of chitosan. The newly developed nanocomposites also showed a significant improvement in electrical conductivity as mentioned from the cyclic voltammetry measurements of the K3[Fe(CN)6] sample. A square-wave adsorptive anodic stripping voltammetry method successfully measured Isoxsuprine hydrochloride using different types of nanocomposite modified CPEs and showed a large enhancement of stripping peak current compared to bare CPE. Consequently, the proposed sensors proved to have a promissing feature for applications in biosensors.
Three modes of high-efficient photocatalysis using composites of TiO2-nanocrystallite-containing mesoporous SiO2 and Au nanoparticles
Journal of Sol-Gel Science and Technology
ABSTRACT Abstract A mesoporous SiO2 template containing TiO2 nanocrystals is synthesized via a so... more ABSTRACT Abstract A mesoporous SiO2 template containing TiO2 nanocrystals is synthesized via a sol-gel route, and Au nanoparticles (NPs) are deposited in the tubular mesochannels of the template by a photodeposition method (Au/SiO2-TiO2). Both of the photocatalytic activities under ultraviolet (UV) and visible (Vis) light irradiation are improved by the deposition of Au NPs. A commercially available photocatalyst, Degussa P25 is employed as a reference, and a comparative study shows that Au/SiO2-TiO2 possesses higher photocatalytic activity than that of P25. An action spectrum of methylene blue (MB) photobleaching using Au/SiO2-TiO2 reveals that the photocatalysis of Au/SiO2-TiO2 is carried out by three triggers: UV absorption by TiO2, and Vis light absorptions by Au NPs and MB. Graphical abstract
Photocatalytic performance of freestanding tetragonal zirconia nanotubes formed in H2O2/NH4F/ethylene glycol electrolyte by anodisation of zirconium
Nanotechnology, 2017
ZrO2 nanotubes (ZrNTs) were produced by anodisation of zirconium foil in H2O2/NH4F/ethylene glyco... more ZrO2 nanotubes (ZrNTs) were produced by anodisation of zirconium foil in H2O2/NH4F/ethylene glycol electrolyte. The as-anodised foils were then soaked in the anodising electrolyte for 12 h. Soaking weakens the adherence of the anodic layer from the substrate resulting in freestanding ZrNTs (FS-ZrNTs). Moreover, the presence of H2O2 in the electrolyte also aids in weakening the adhesion of the film from the foil, as foil anodised in electrolyte without H2O2 has good film adherence. The as-anodised FS-ZrNTs film was amorphous and crystallised to predominantly tetragonal phase upon annealing at >300 °C. Annealing must, however, be done at <500 °C to avoid monoclinic ZrO2 formation and nanotubes disintegration. FS-ZrNTs annealed at 450 °C exhibited the highest photocatalytic ability to degrade methyl orange (MO), whereby 82% MO degradation was observed after 5 h, whereas FS-ZrNTs with a mixture of monoclinic and tetragonal degraded 70% of MO after 5 h.
Ag nanoparticle-filled TiO2 nanotube arrays prepared by anodization and electrophoretic deposition for dye-sensitized solar cells
Nanotechnology, 2017
A layer of TiO2 nanotube (TNT) arrays with a thickness of 13 μm is synthesized by a two-step anod... more A layer of TiO2 nanotube (TNT) arrays with a thickness of 13 μm is synthesized by a two-step anodic oxidation from Ti metal foil. Surface charged Ag nanoparticles (NPs) are prepared by chemical reduction. After a pretreatment of the TNT arrays by acetone vapor, Ag NP filled TNT arrays can be achieved by electrophoretic deposition (EPD). Effects of the applied voltage during EPD such as DC-AC difference, frequency and waveform are investigated by quantitative analysis using atomic absorption spectroscopy. The results show that the best EPD condition is using DC 2 V + AC 4 V and a square wave of 1 Hz as the applied voltage. Back illuminated dye-sensitized solar cells are fabricated from TNT arrays with and without Ag NPs. The efficiency increased from 3.70% to 5.01% by the deposition of Ag NPs.
Formation of grassy TiO2 nanotube thin film by anodisation in peroxide electrolyte for Cr(VI) removal under ultraviolet radiation
Nanotechnology
Honeycomb-like open-edged reduced-graphene-oxide-enclosed transition metal oxides (NiO/Co3O4) as improved electrode materials for high-performance supercapacitor
Journal of Energy Storage
Fe3O4-embedded rGO composites as anode for rechargeable FeOx-air batteries
Materials Today Communications
Comparison of ZrO2, TiO2, and α-Fe2O3 nanotube arrays on Cr(VI) photoreduction fabricated by anodization of Zr, Ti, and Fe foils
Materials Research Express
Parameters and Underlying Mechanisms Affecting the Morphology of Bifurcating TiO2 Nanotube
ECS Meeting Abstracts
Nanomaterials
Micro/nanoscale design of composite materials enables alteration of their properties for advanced... more Micro/nanoscale design of composite materials enables alteration of their properties for advanced functional materials. One of the biggest challenges in material design is the controlled decoration of composite materials with the desired functional additives. This study reports on and demonstrates the homogeneous decoration of hexagonal boron nitride (hBN) on poly(methylmethacrylate) (PMMA) and vice versa. The formation of the composite materials was conducted via a low environmental load and a low-energy-consuming, electrostatic nano-assembly method which also enabled the efficient usage of nano-sized additives. The hBN/PMMA and PMMA/hBN composites were fabricated in various size combinations that exhibited percolated and layer-oriented structures, respectively. The thermal conductivity behaviors of hBN/PMMA and PMMA/hBN composites that exhibited good microstructure were compared. The results showed that microstructural design of the composites enabled the modification of their hea...
Synthesis of mesoporous Co(OH)2 nanostructure film via electrochemical deposition using lyotropic liquid crystal template as improved electrode materials for supercapacitors application
Journal of Electroanalytical Chemistry
Nanoscale Research Letters
This work reports on a novel controlled nanocomposite fabrication technique which is applicable f... more This work reports on a novel controlled nanocomposite fabrication technique which is applicable for material design via a micro-and nano-assembly method. The principle is based on the use of electrostatic adsorption of the surface charge-modified particles via layer-by-layer assembly. The polarity and the zeta potential of the surface charge was controlled using polycation and polyanion, while the zeta potential strength was controlled via the number of alternating coating layers which was determined using zeta potential measurement. A systematic study was conducted to demonstrate the feasibility of composite material assembly via electrostatic adsorption using alumina (Al 2 O 3 ) and silica (SiO 2 ) composite as a study model, which was carried out as a function of surface zeta potential, surface coverage percentage, and processing time. The considerable potential of this technique for composite material design is also further demonstrated with controlled assembly involving different materials in various structural forms such as fiber, whisker, nanosheets, and even irregular-shaped foam-like structured urethane. The composite materials designed using this EA method possess good potentials to be utilized for various applications such as mechanical property control, composite ceramic films formation, selective laser sintering, and rechargeable metal-air battery.
Nanomaterials
Formation of functional composite materials with desired properties is important for advanced app... more Formation of functional composite materials with desired properties is important for advanced application development. However, formation of a homogenous composite material via conventional mixing methods still remains a challenge due to agglomeration. Therefore, this work reports and demonstrates the formation of a homogeneous poly(methylmethacrylate) (PMMA)-indium tin oxide (ITO) composite with high visible light transparency (up to 90%) with an excellent shielding effect of infra-red (IR) via a facile electrostatic assembly method. This PMMA-ITO composite with good transparency and an IR shielding effect has good potential to be used in the automobile industry for vehicle windscreens as well as in heat preservation or preventive technology. The IR shielding rate is demonstrated to be controllable by changing the amount of ITO nanoparticles additive. This finding would provide a platform for development of IR optical related polymeric composite materials.
Anhydrous proton conductive xCHS-(1-x)WSiA composites prepared via liquid-phase shaking
Solid State Ionics
Science and Technology of Advanced Materials
We report a novel and inexpensive fabrication process of multiferroic nanocomposite via liquid ph... more We report a novel and inexpensive fabrication process of multiferroic nanocomposite via liquid phase using an anodic alumina template. The sol-gel spin-coating technique was used to coat the template with ferrimagnetic CoFe 2 O 4 . By dissolving the template with NaOH aqueous solution, a unique nanotube array structure of CoFe 2 O 4 was obtained. The CoFe 2 O 4 nanotube arrays were filled with, and sandwiched in, ferroelectric BaTiO 3 layers by a sol-gel spin-coating method to obtain the composite. Its multiferroicity was confirmed by measuring the magnetic and dielectric hysteresis loops.
Investigation of the anchor layer formation on different substrates and its feasibility for optical properties control by aerosol deposition
Applied Surface Science
E3S Web of Conferences
Inorganic-organic composite membranes were prepared by using partly cesium-substituted silicotung... more Inorganic-organic composite membranes were prepared by using partly cesium-substituted silicotungstic acid (CHS-WSiA) and polybenzimidazole (PBI, MRS0810H) for medium temperature polymer electrolyte fuel cells (MT-PEFCs). Cesium hydrogen sulfate (CsHSO4, CHS) and silicotungstic acid (H4SiW12O40, WSiA) were milled to obtain 0.5CHS-0.5WSiA composites by dry and wet mechanical millings. N,Ndimethylacetamide (DMAc) was used as a disperse medium in the preparation of the inorganic solid acids by wet mechanical milling and also a casting agent for fabrication of membrane. Finally, flexible and homogeneous composite membranes with several phosphoric acid doping levels (PADLs) were obtained. The wet mechanical milling using DMAc was found to effectively promote good substitution of H+ ion in WSiA by Cs+ ion of CHS and promoted the formation of smaller grain sizes of composites, compared with dry milling. A high maximum power density of 378 mWcm-2 and a good constant current stability test w...
Sol-gel template synthesis of BaTiO3 films with nano-periodic structures
Materials Letters
Journal of the Ceramic Society of Japan
Demand for low-cost, environmentally friendly alternative renewable energy sources makes the dye-... more Demand for low-cost, environmentally friendly alternative renewable energy sources makes the dye-sensitized solar cell (DSSC) a viable alternative. DSSCs have a high but competitively challenged power conversion efficiency (PCE) of 11.9%. Plasmonic DSSCs is one approach with extreme enhancement of light absorption to increasing the PCE. The highest PCE of plasmonic DSSCs is still <11% however, due to secondary effects which are not yet well understood. In this study, we used a complex composite of plasmonic nanoparticles (PNPs) with extended characterization and wide ranging PNP loadings, combined with a systematic approach to obtain synergistic effects and a deeper understanding of the effects of plasmonic nanostructures on DSSC performance. The results showed two optimal loading amounts of PNPs with enhanced PCEs of 4.26 and 4.36% (from 3.54%), with enhancement effects obtained mainly from efficient charge injection and a balance of the negative and positive effects of the PNPs, respectively. An increase in the photoanode thickness from 5.5 to 9¯m resulted in PCE enhancement from 4.39 to 4.58%, mainly via efficient charge injection. The PNPs had both positive and negative effects on key DSSC performance parameters: decreased photoanode surface area but with panchromatic enhancement of light absorbance; increased short circuit current up to a point followed by a decrease due to poor charge injection; increased open circuit voltage and fill factor; enhanced charge transfer resistance against charge recombination; improved electron lifetime and charge collection efficiency; lowered enhancement of cell performance in the near infra-red region; and induced abundantly generated electrons augmented charge recombination. These results contribute significantly to understanding of the effects of plasmonic nanostructures and can serve as a useful guide to the study of plasmonic DSSCs and related fields.
Annealing temperature-dependent crystallinity and photocurrent response of anodic nanoporous iron oxide film
Journal of Materials Research
Fabrication of biosensor based on Chitosan-ZnO/Polypyrrole nanocomposite modified carbon paste electrode for electroanalytical application
Materials Science and Engineering: C
A sensitive conductive nanocomposite sensor consisting of chitosan, zinc oxide nanoparticles, and... more A sensitive conductive nanocomposite sensor consisting of chitosan, zinc oxide nanoparticles, and polypyrrole was developed. The sensor was prepared by oxidative polymerization of pyrrole using (NH4)2S2O8 as the oxidant followed by mixing a Chitosan-Zinc oxide composite with a different content of Chitosan. The morphology and surface area of the nanocomposites were changed by changing the percentage of chitosan. The newly developed nanocomposites also showed a significant improvement in electrical conductivity as mentioned from the cyclic voltammetry measurements of the K3[Fe(CN)6] sample. A square-wave adsorptive anodic stripping voltammetry method successfully measured Isoxsuprine hydrochloride using different types of nanocomposite modified CPEs and showed a large enhancement of stripping peak current compared to bare CPE. Consequently, the proposed sensors proved to have a promissing feature for applications in biosensors.
Three modes of high-efficient photocatalysis using composites of TiO2-nanocrystallite-containing mesoporous SiO2 and Au nanoparticles
Journal of Sol-Gel Science and Technology
ABSTRACT Abstract A mesoporous SiO2 template containing TiO2 nanocrystals is synthesized via a so... more ABSTRACT Abstract A mesoporous SiO2 template containing TiO2 nanocrystals is synthesized via a sol-gel route, and Au nanoparticles (NPs) are deposited in the tubular mesochannels of the template by a photodeposition method (Au/SiO2-TiO2). Both of the photocatalytic activities under ultraviolet (UV) and visible (Vis) light irradiation are improved by the deposition of Au NPs. A commercially available photocatalyst, Degussa P25 is employed as a reference, and a comparative study shows that Au/SiO2-TiO2 possesses higher photocatalytic activity than that of P25. An action spectrum of methylene blue (MB) photobleaching using Au/SiO2-TiO2 reveals that the photocatalysis of Au/SiO2-TiO2 is carried out by three triggers: UV absorption by TiO2, and Vis light absorptions by Au NPs and MB. Graphical abstract
Photocatalytic performance of freestanding tetragonal zirconia nanotubes formed in H2O2/NH4F/ethylene glycol electrolyte by anodisation of zirconium
Nanotechnology, 2017
ZrO2 nanotubes (ZrNTs) were produced by anodisation of zirconium foil in H2O2/NH4F/ethylene glyco... more ZrO2 nanotubes (ZrNTs) were produced by anodisation of zirconium foil in H2O2/NH4F/ethylene glycol electrolyte. The as-anodised foils were then soaked in the anodising electrolyte for 12 h. Soaking weakens the adherence of the anodic layer from the substrate resulting in freestanding ZrNTs (FS-ZrNTs). Moreover, the presence of H2O2 in the electrolyte also aids in weakening the adhesion of the film from the foil, as foil anodised in electrolyte without H2O2 has good film adherence. The as-anodised FS-ZrNTs film was amorphous and crystallised to predominantly tetragonal phase upon annealing at >300 °C. Annealing must, however, be done at <500 °C to avoid monoclinic ZrO2 formation and nanotubes disintegration. FS-ZrNTs annealed at 450 °C exhibited the highest photocatalytic ability to degrade methyl orange (MO), whereby 82% MO degradation was observed after 5 h, whereas FS-ZrNTs with a mixture of monoclinic and tetragonal degraded 70% of MO after 5 h.
Ag nanoparticle-filled TiO2 nanotube arrays prepared by anodization and electrophoretic deposition for dye-sensitized solar cells
Nanotechnology, 2017
A layer of TiO2 nanotube (TNT) arrays with a thickness of 13 μm is synthesized by a two-step anod... more A layer of TiO2 nanotube (TNT) arrays with a thickness of 13 μm is synthesized by a two-step anodic oxidation from Ti metal foil. Surface charged Ag nanoparticles (NPs) are prepared by chemical reduction. After a pretreatment of the TNT arrays by acetone vapor, Ag NP filled TNT arrays can be achieved by electrophoretic deposition (EPD). Effects of the applied voltage during EPD such as DC-AC difference, frequency and waveform are investigated by quantitative analysis using atomic absorption spectroscopy. The results show that the best EPD condition is using DC 2 V + AC 4 V and a square wave of 1 Hz as the applied voltage. Back illuminated dye-sensitized solar cells are fabricated from TNT arrays with and without Ag NPs. The efficiency increased from 3.70% to 5.01% by the deposition of Ag NPs.