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Papers by TRAN VAN KHAI

Research on the Content of KOH on Microstructure Property of Rice Hull-Based Biochar Using Pyrolyzed Process

Springer proceedings in physics, 2023

Han'gug gyeoljeong seongjang haghoeji, Feb 28, 2013

ZnO with different morphologies can be used various application depending on their shapes. Differ... more ZnO with different morphologies can be used various application depending on their shapes. Different morphologies of ZnO structures were synthesized by a catalysis-free thermal evaporation process. Their morphologies were dependent on the distance from the source to substrate on the same processing condition; in the result were products morphologies of the hollow, cage and star. Their shapes and crystalinity were evaluated by SEM and XRD, respectively. This work demonstrates what kind of growth factors would be involved in the final structure morphologies.

Effects of pH on the Structure and Optical Property of Molybdenum Disulfide Nanocrystals Synthesized by Hydrothermal Method

Chiang Mai Journal of Science, Mar 31, 2023

Vietnam Journal of Science and Technology, Oct 28, 2019

A simple and straightforward approach was used to prepare Fe 2 O 3 /graphene nanocomposites with ... more A simple and straightforward approach was used to prepare Fe 2 O 3 /graphene nanocomposites with different temperature conditions. The nanocomposites were characterized by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning microscopy (FE-SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and photoluminescence (PL). The results show that Fe 2 O 3 nanoparticles with size in range of 60-100 nm are anchored on the surface and filled between the graphene nanosheets at hydrothermal reaction. The PL spectrum exhibits the emission peaks appeared at ~ 650 nm and ~ 720 nm.

Microwave-Assisted Synthesis of Silver Nanoparticles Using Chitosan: A Novel Approach

Materials and Manufacturing Processes, Apr 1, 2014

ABSTRACT In this work, microwave-assisted (MwH) synthesis of silver nanoparticles (AgNPs) using c... more ABSTRACT In this work, microwave-assisted (MwH) synthesis of silver nanoparticles (AgNPs) using chitosan was investigated. The new method was compared against chemical reduction (CRed) by NaBH4 and conventional thermal method (CvH). The as-synthesized AgNPs were characterized by UV–Visible spectroscopy, transmission electron microscopy (TEM) and infrared spectroscopy. The MwH method was found to effectively synthesize AgNPs of which properties were comparable CRed and CvH. The average particle sizes of AgNPs produced by CRed, CvH and MwH were approximately 20, 5 and 7 nm, respectively. The proposed approach can provide a viable green route for synthesizing AgNPs with high potential applicability.

Crystals, Dec 14, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Crystals

The purpose of this study is to synthesize and explore the relationship between the optical prope... more The purpose of this study is to synthesize and explore the relationship between the optical properties and gas-sensing performance of ZnO nanowires (NWs). Well-aligned ZnO nanowire (NW) arrays were synthesized on a silicon substrate using the thermal evaporation method without any catalyst or additive. The structures, surface morphologies, chemical compositions, and optical properties of the products were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) together with energy-dispersive spectroscopy (EDS), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy, and their gas-sensing properties for NO2 were examined. The results showed that single-crystalline ZnO NWs with high density grow uniformly and vertically on a Si substrate. The FESEM and TEM images indicate that ZnO NWs have an average diameter of roughly 135–160 nm with an average length of roughl...

Acta Scientiarum Polonorum Technologia Alimentaria

Background. Pleurotus sajor-caju has nutritional and medicinal values but it cannot be stored for... more Background. Pleurotus sajor-caju has nutritional and medicinal values but it cannot be stored for more than 24 hours at room temperature because of its high water content. In addition, using the Modified Atmosphere in Packaging (MAP) method to store fresh mushrooms is an effective way to extend their shelf life. Materials and methods. The protein, total sugar and lipid contents were determined for fresh oyster mushrooms packed in paper (P), high-density polyethylene (HDPE) and polyethylene terephthalate (PET) at 3-5°C and 28-30°C (with 60-62% and 76-78% of air humidy, respectively) during storage. The kinetics of chemical degradation were explored, and the best model was selected based on the highest R 2 value and the lowest RMSE value. Results. The loss of protein, total sugar and total lipid contents were lowest in the samples packed in HDPE packaging. Changes in the kinetics of protein and total sugar in different packaging and temperatures during storage followed the first-order model, while changes in total lipid followed the zero-order model. The halflife (t 1/2) values of the samples at 3-5°C were 4-5 times higher than at 28-30°C. Conclusion. The use of HDPE packaging was effective in maintaining the composition of Pleurotus sajor-caju at 28-30°C for 2-3 days and 13-15 days at 3-5°C.

Vietnam Journal of Science and Technology, 2019

In this report, thin layers of MoS2 were in-situ incorporated into graphene oxide (GO) to form Mo... more In this report, thin layers of MoS2 were in-situ incorporated into graphene oxide (GO) to form MoS2/graphene nanocomposite by a facile ultrasonic-assisted hydrothermal method. X-ray Diffraction (XRD) and Raman analysis revealed that the as-synthesized MoS2 nanosheets crystalized in hexagonal phase 2H-MoS2 while High Resolution Transmission Electron Microscopy (HRTEM) images confirmed that MoS2 layers with average thickness of ~5–6 nm (6–8 layers) attached on the edges and surfaces of graphene sheets with high density and uniform shape restacking in three-dimensional (3D) architectures. The Scanning Transmission Electron Microscopy – Energy Dispersive X-ray spectrum (STEM-EDX) investigation further confirmed the low impurity of MoS2/graphene composite, and the well repairing of defects in GO surfaces during the hydrothermal process. Our approach is promising for a scalable, inexpensive, and accurate strategy to fabricate state-of-the-art materials with a certain structure for various...

Vietnam Journal of Science and Technology, 2019

In this report, thin layers of MoS2 were in-situ incorporated into graphene oxide (GO) to form Mo... more In this report, thin layers of MoS2 were in-situ incorporated into graphene oxide (GO) to form MoS2/graphene nanocomposite by a facile ultrasonic-assisted hydrothermal method. X-ray Diffraction (XRD) and Raman analysis revealed that the as-synthesized MoS2 nanosheets crystalized in hexagonal phase 2H-MoS2 while High Resolution Transmission Electron Microscopy (HRTEM) images confirmed that MoS2 layers with average thickness of ~5–6 nm (6–8 layers) attached on the edges and surfaces of graphene sheets with high density and uniform shape restacking in three-dimensional (3D) architectures. The Scanning Transmission Electron Microscopy – Energy Dispersive X-ray spectrum (STEM-EDX) investigation further confirmed the low impurity of MoS2/graphene composite, and the well repairing of defects in GO surfaces during the hydrothermal process. Our approach is promising for a scalable, inexpensive, and accurate strategy to fabricate state-of-the-art materials with a certain structure for various...

Controllable synthesis by hydrothermal method and optical properties of 2D MoS2/rGO nanocomposites

Journal of Sol-Gel Science and Technology

Journal of the Korean Crystal Growth and Crystal Technology, 2013

ZnO with different morphologies can be used various application depending on their shapes. Differ... more ZnO with different morphologies can be used various application depending on their shapes. Different morphologies of ZnO structures were synthesized by a catalysis-free thermal evaporation process. Their morphologies were dependent on the distance from the source to substrate on the same processing condition; in the result were products morphologies of the hollow, cage and star. Their shapes and crystalinity were evaluated by SEM and XRD, respectively. This work demonstrates what kind of growth factors would be involved in the final structure morphologies.

Au-assisted growth, Raman spectra, and photoluminescence of Mg2SiO4 nanowires

Ceramic Research Institute, Jun 1, 2012

Journal of the Korean Crystal Growth and Crystal Technology, 2012

Recently the preparation magnetic nanoparticles by a pulsed laser ablation in liquid has gained m... more Recently the preparation magnetic nanoparticles by a pulsed laser ablation in liquid has gained much attention because it is easy to control experimental parameters. Iron oxide magnetic nanoparticles have been prepared by a pulsed laser ablation of α-Fe 2 O 3 target in ethanol at different magnitude of laser energy of 1, 20, 40 and 80 mJ/pulse. It revealed that particle size increases with increasing laser energy. It could be concluded that 40 mJ/pulse is an optimum laser energy for the preparation of iron oxide nanoparticles with uniform size distribution. The nanoparticles are homogeneously dispersed in ethanol and their stability maintained for several months.

Vietnam Journal of Science and Technology, Mar 23, 2018

In this research, few-layer-graphene (FLG) sheets had been successfully fabricated by using a mic... more In this research, few-layer-graphene (FLG) sheets had been successfully fabricated by using a microwave-assisted method. First, graphite intercalation compounds were prepared from potassium-tetrahydrofuran (K-THF)-expanded graphite by solvothermal process, and then the exfoliation was assisted by microwave radiation and sonication process. The resulted nanographene has average thickness about ~ 2 nm with a lateral size of 3-7 μm. Raman analysis showed that the as-synthesized graphene nanosheets contain only a few numbers of structural defects or impurities. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy spectra revealed that the nano-graphene consisted of several peaks similar to those of graphite, indicating the effectiveness of the solvothermal reduction method in lowering the oxygen level. The electrical conductivity of the as-synthesized nano-graphene was measured to be 170 S/m. In contrast to the Hummer method, the method is simple, inexpensive, and does not generate toxic gas. This simple method could provide the synthesis of high quality nanographene on a large scale.

Vietnam Journal of Science and Technology, Mar 23, 2018

Vertically well-aligned ZnO nanowire (NW) arrays with high density were directly synthesized on g... more Vertically well-aligned ZnO nanowire (NW) arrays with high density were directly synthesized on graphene/Si substrate by thermal evaporation of zinc powder without catalysts or additives. The ZnO NWs were characterized by field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), photoluminescence (PL), and Raman spectroscopy. The results showed that the obtained ZnO NWs have diameters in the range of 300-350 nm with lengths of several tens micrometers. The prepared ZnO NWs are of a single crystal, which have a hexagonal wurtzite crystal structure with c-axis (002) orientation growth perpendicular to the substrate surface. The NW arrays had a good crystal quality with excellent optical properties, indicating a sharp and strong ultraviolet emission at 380 nm, and a weak visible emission at around 516 nm.

Catalyst-free growth of ZnO nanowires on Si (100) substrates by thermal evaporation

Journal of Ceramic Processing Research, 2011

High-quality graphene thin films synthesized by H 2 ambient-annealing of reduced graphene oxide sheets

Highly conductive low-oxygen graphene thin films were produced by thermal annealing of chemically... more Highly conductive low-oxygen graphene thin films were produced by thermal annealing of chemically reduced graphene oxide (RGO) sheets under H2 ambient. X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy measurements showed that the thermal annealing efficiently removed residual oxygen-containing functional groups on the surface of the chemically reduced RGO sheets and simultaneously recovered sp carbon networks in the graphene sheets. Consequently, the electrical conductivity of the graphene films was greatly improved, from 24 S/cm for RGO films to 200 S/cm after the thermal annealing process. In addition, we have studied the NO2 gas sensing characteristics of the prepared graphene films.

Preparation and characterization of nanocomposite based on polyaniline and graphene nanosheets

Polymer nanocomposites based on polyaniline (PANi) and graphene nanosheets (GNS) modified with po... more Polymer nanocomposites based on polyaniline (PANi) and graphene nanosheets (GNS) modified with poly(sodium 4-styrensulfonate) (PSS-GNS) were prepared, and their structure and properties were investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), UV-vis spectroscopy, ATR-IR spectroscopy, X-ray diffraction, elemental analysis, thermogravimetric analysis (TGA) and electrical conductivity measurements. The results revealed that for the PANi/PSS-GNS nanocomposites, the disordered structure of PSS-GNS was fully destroyed and PSS-GNS exists in the form of a single GNS or stacked PSS-GNS elements in a PANi matrix. PSS-GNS was partly covered by PANi due to hydrogen bonding that occurs between the PSS-GNS and PANi. By incorporating PSS-GNS, the electrical conductivity of PANi increased linearly from 0.84 S/cm for neat PANi to 4.96 S/cm for a PANi/PSS-GNS (5%) nanocomposite. The thermal stability of the PANi was also improved significantly to approximately 100 °C by...

Synthesis of Ag/GO nanocomposite with promising photocatalytic ability for reduction reaction of p-nitrophenol

Materials Research Express

p-Aminophenol (PAP) is an important intermediate reagent in the synthesis of paracetamol, widely ... more p-Aminophenol (PAP) is an important intermediate reagent in the synthesis of paracetamol, widely used as an analgesic and antipyretic drug. Therefore, finding an effective catalyst to improve PAP synthesis efficiency is worth studying. Among those studies, nanocomposite is the most promising material. In this study, Ag/GO nanocomposites were synthesized by reducing silver nitrate on graphene oxide (GO) with sodium borohydride as a reducing agent and characterized by SEM, EDX, XRD and UV–vis methods. The catalytic ability was investigated based on the hydrogenation reaction of p-nitrophenol (PNP). We successfully synthesized Ag/GO nanocomposite with relatively homogeneous distributions and similar particle sizes. The results showed that Ag/GO nanocomposite has an excellent catalytic activity with the yield of reduction reaction at 97%, 3 min. Moreover, this photocatalyst can easily be recovered and reused three times without any reaction efficiency reduction. We also successfully synthesized and crystallized PAP with high purity and the total yield of 45.82%. The results show that Ag/GO nanocomposite is an excellent catalyst for high-performance reactions with many useful properties, such as easily recovered and repetitive used. On top of that, Ag/GO nanocomposite is safe, less toxic and environmentally friendly.

Research on the Content of KOH on Microstructure Property of Rice Hull-Based Biochar Using Pyrolyzed Process

Springer proceedings in physics, 2023

Han'gug gyeoljeong seongjang haghoeji, Feb 28, 2013

ZnO with different morphologies can be used various application depending on their shapes. Differ... more ZnO with different morphologies can be used various application depending on their shapes. Different morphologies of ZnO structures were synthesized by a catalysis-free thermal evaporation process. Their morphologies were dependent on the distance from the source to substrate on the same processing condition; in the result were products morphologies of the hollow, cage and star. Their shapes and crystalinity were evaluated by SEM and XRD, respectively. This work demonstrates what kind of growth factors would be involved in the final structure morphologies.

Effects of pH on the Structure and Optical Property of Molybdenum Disulfide Nanocrystals Synthesized by Hydrothermal Method

Chiang Mai Journal of Science, Mar 31, 2023

Vietnam Journal of Science and Technology, Oct 28, 2019

A simple and straightforward approach was used to prepare Fe 2 O 3 /graphene nanocomposites with ... more A simple and straightforward approach was used to prepare Fe 2 O 3 /graphene nanocomposites with different temperature conditions. The nanocomposites were characterized by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning microscopy (FE-SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and photoluminescence (PL). The results show that Fe 2 O 3 nanoparticles with size in range of 60-100 nm are anchored on the surface and filled between the graphene nanosheets at hydrothermal reaction. The PL spectrum exhibits the emission peaks appeared at ~ 650 nm and ~ 720 nm.

Microwave-Assisted Synthesis of Silver Nanoparticles Using Chitosan: A Novel Approach

Materials and Manufacturing Processes, Apr 1, 2014

ABSTRACT In this work, microwave-assisted (MwH) synthesis of silver nanoparticles (AgNPs) using c... more ABSTRACT In this work, microwave-assisted (MwH) synthesis of silver nanoparticles (AgNPs) using chitosan was investigated. The new method was compared against chemical reduction (CRed) by NaBH4 and conventional thermal method (CvH). The as-synthesized AgNPs were characterized by UV–Visible spectroscopy, transmission electron microscopy (TEM) and infrared spectroscopy. The MwH method was found to effectively synthesize AgNPs of which properties were comparable CRed and CvH. The average particle sizes of AgNPs produced by CRed, CvH and MwH were approximately 20, 5 and 7 nm, respectively. The proposed approach can provide a viable green route for synthesizing AgNPs with high potential applicability.

Crystals, Dec 14, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Crystals

The purpose of this study is to synthesize and explore the relationship between the optical prope... more The purpose of this study is to synthesize and explore the relationship between the optical properties and gas-sensing performance of ZnO nanowires (NWs). Well-aligned ZnO nanowire (NW) arrays were synthesized on a silicon substrate using the thermal evaporation method without any catalyst or additive. The structures, surface morphologies, chemical compositions, and optical properties of the products were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) together with energy-dispersive spectroscopy (EDS), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy, and their gas-sensing properties for NO2 were examined. The results showed that single-crystalline ZnO NWs with high density grow uniformly and vertically on a Si substrate. The FESEM and TEM images indicate that ZnO NWs have an average diameter of roughly 135–160 nm with an average length of roughl...

Acta Scientiarum Polonorum Technologia Alimentaria

Background. Pleurotus sajor-caju has nutritional and medicinal values but it cannot be stored for... more Background. Pleurotus sajor-caju has nutritional and medicinal values but it cannot be stored for more than 24 hours at room temperature because of its high water content. In addition, using the Modified Atmosphere in Packaging (MAP) method to store fresh mushrooms is an effective way to extend their shelf life. Materials and methods. The protein, total sugar and lipid contents were determined for fresh oyster mushrooms packed in paper (P), high-density polyethylene (HDPE) and polyethylene terephthalate (PET) at 3-5°C and 28-30°C (with 60-62% and 76-78% of air humidy, respectively) during storage. The kinetics of chemical degradation were explored, and the best model was selected based on the highest R 2 value and the lowest RMSE value. Results. The loss of protein, total sugar and total lipid contents were lowest in the samples packed in HDPE packaging. Changes in the kinetics of protein and total sugar in different packaging and temperatures during storage followed the first-order model, while changes in total lipid followed the zero-order model. The halflife (t 1/2) values of the samples at 3-5°C were 4-5 times higher than at 28-30°C. Conclusion. The use of HDPE packaging was effective in maintaining the composition of Pleurotus sajor-caju at 28-30°C for 2-3 days and 13-15 days at 3-5°C.

Vietnam Journal of Science and Technology, 2019

In this report, thin layers of MoS2 were in-situ incorporated into graphene oxide (GO) to form Mo... more In this report, thin layers of MoS2 were in-situ incorporated into graphene oxide (GO) to form MoS2/graphene nanocomposite by a facile ultrasonic-assisted hydrothermal method. X-ray Diffraction (XRD) and Raman analysis revealed that the as-synthesized MoS2 nanosheets crystalized in hexagonal phase 2H-MoS2 while High Resolution Transmission Electron Microscopy (HRTEM) images confirmed that MoS2 layers with average thickness of ~5–6 nm (6–8 layers) attached on the edges and surfaces of graphene sheets with high density and uniform shape restacking in three-dimensional (3D) architectures. The Scanning Transmission Electron Microscopy – Energy Dispersive X-ray spectrum (STEM-EDX) investigation further confirmed the low impurity of MoS2/graphene composite, and the well repairing of defects in GO surfaces during the hydrothermal process. Our approach is promising for a scalable, inexpensive, and accurate strategy to fabricate state-of-the-art materials with a certain structure for various...

Vietnam Journal of Science and Technology, 2019

In this report, thin layers of MoS2 were in-situ incorporated into graphene oxide (GO) to form Mo... more In this report, thin layers of MoS2 were in-situ incorporated into graphene oxide (GO) to form MoS2/graphene nanocomposite by a facile ultrasonic-assisted hydrothermal method. X-ray Diffraction (XRD) and Raman analysis revealed that the as-synthesized MoS2 nanosheets crystalized in hexagonal phase 2H-MoS2 while High Resolution Transmission Electron Microscopy (HRTEM) images confirmed that MoS2 layers with average thickness of ~5–6 nm (6–8 layers) attached on the edges and surfaces of graphene sheets with high density and uniform shape restacking in three-dimensional (3D) architectures. The Scanning Transmission Electron Microscopy – Energy Dispersive X-ray spectrum (STEM-EDX) investigation further confirmed the low impurity of MoS2/graphene composite, and the well repairing of defects in GO surfaces during the hydrothermal process. Our approach is promising for a scalable, inexpensive, and accurate strategy to fabricate state-of-the-art materials with a certain structure for various...

Controllable synthesis by hydrothermal method and optical properties of 2D MoS2/rGO nanocomposites

Journal of Sol-Gel Science and Technology

Journal of the Korean Crystal Growth and Crystal Technology, 2013

ZnO with different morphologies can be used various application depending on their shapes. Differ... more ZnO with different morphologies can be used various application depending on their shapes. Different morphologies of ZnO structures were synthesized by a catalysis-free thermal evaporation process. Their morphologies were dependent on the distance from the source to substrate on the same processing condition; in the result were products morphologies of the hollow, cage and star. Their shapes and crystalinity were evaluated by SEM and XRD, respectively. This work demonstrates what kind of growth factors would be involved in the final structure morphologies.

Au-assisted growth, Raman spectra, and photoluminescence of Mg2SiO4 nanowires

Ceramic Research Institute, Jun 1, 2012

Journal of the Korean Crystal Growth and Crystal Technology, 2012

Recently the preparation magnetic nanoparticles by a pulsed laser ablation in liquid has gained m... more Recently the preparation magnetic nanoparticles by a pulsed laser ablation in liquid has gained much attention because it is easy to control experimental parameters. Iron oxide magnetic nanoparticles have been prepared by a pulsed laser ablation of α-Fe 2 O 3 target in ethanol at different magnitude of laser energy of 1, 20, 40 and 80 mJ/pulse. It revealed that particle size increases with increasing laser energy. It could be concluded that 40 mJ/pulse is an optimum laser energy for the preparation of iron oxide nanoparticles with uniform size distribution. The nanoparticles are homogeneously dispersed in ethanol and their stability maintained for several months.

Vietnam Journal of Science and Technology, Mar 23, 2018

In this research, few-layer-graphene (FLG) sheets had been successfully fabricated by using a mic... more In this research, few-layer-graphene (FLG) sheets had been successfully fabricated by using a microwave-assisted method. First, graphite intercalation compounds were prepared from potassium-tetrahydrofuran (K-THF)-expanded graphite by solvothermal process, and then the exfoliation was assisted by microwave radiation and sonication process. The resulted nanographene has average thickness about ~ 2 nm with a lateral size of 3-7 μm. Raman analysis showed that the as-synthesized graphene nanosheets contain only a few numbers of structural defects or impurities. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy spectra revealed that the nano-graphene consisted of several peaks similar to those of graphite, indicating the effectiveness of the solvothermal reduction method in lowering the oxygen level. The electrical conductivity of the as-synthesized nano-graphene was measured to be 170 S/m. In contrast to the Hummer method, the method is simple, inexpensive, and does not generate toxic gas. This simple method could provide the synthesis of high quality nanographene on a large scale.

Vietnam Journal of Science and Technology, Mar 23, 2018

Vertically well-aligned ZnO nanowire (NW) arrays with high density were directly synthesized on g... more Vertically well-aligned ZnO nanowire (NW) arrays with high density were directly synthesized on graphene/Si substrate by thermal evaporation of zinc powder without catalysts or additives. The ZnO NWs were characterized by field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), photoluminescence (PL), and Raman spectroscopy. The results showed that the obtained ZnO NWs have diameters in the range of 300-350 nm with lengths of several tens micrometers. The prepared ZnO NWs are of a single crystal, which have a hexagonal wurtzite crystal structure with c-axis (002) orientation growth perpendicular to the substrate surface. The NW arrays had a good crystal quality with excellent optical properties, indicating a sharp and strong ultraviolet emission at 380 nm, and a weak visible emission at around 516 nm.

Catalyst-free growth of ZnO nanowires on Si (100) substrates by thermal evaporation

Journal of Ceramic Processing Research, 2011

High-quality graphene thin films synthesized by H 2 ambient-annealing of reduced graphene oxide sheets

Highly conductive low-oxygen graphene thin films were produced by thermal annealing of chemically... more Highly conductive low-oxygen graphene thin films were produced by thermal annealing of chemically reduced graphene oxide (RGO) sheets under H2 ambient. X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy measurements showed that the thermal annealing efficiently removed residual oxygen-containing functional groups on the surface of the chemically reduced RGO sheets and simultaneously recovered sp carbon networks in the graphene sheets. Consequently, the electrical conductivity of the graphene films was greatly improved, from 24 S/cm for RGO films to 200 S/cm after the thermal annealing process. In addition, we have studied the NO2 gas sensing characteristics of the prepared graphene films.

Preparation and characterization of nanocomposite based on polyaniline and graphene nanosheets

Polymer nanocomposites based on polyaniline (PANi) and graphene nanosheets (GNS) modified with po... more Polymer nanocomposites based on polyaniline (PANi) and graphene nanosheets (GNS) modified with poly(sodium 4-styrensulfonate) (PSS-GNS) were prepared, and their structure and properties were investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), UV-vis spectroscopy, ATR-IR spectroscopy, X-ray diffraction, elemental analysis, thermogravimetric analysis (TGA) and electrical conductivity measurements. The results revealed that for the PANi/PSS-GNS nanocomposites, the disordered structure of PSS-GNS was fully destroyed and PSS-GNS exists in the form of a single GNS or stacked PSS-GNS elements in a PANi matrix. PSS-GNS was partly covered by PANi due to hydrogen bonding that occurs between the PSS-GNS and PANi. By incorporating PSS-GNS, the electrical conductivity of PANi increased linearly from 0.84 S/cm for neat PANi to 4.96 S/cm for a PANi/PSS-GNS (5%) nanocomposite. The thermal stability of the PANi was also improved significantly to approximately 100 °C by...

Synthesis of Ag/GO nanocomposite with promising photocatalytic ability for reduction reaction of p-nitrophenol

Materials Research Express

p-Aminophenol (PAP) is an important intermediate reagent in the synthesis of paracetamol, widely ... more p-Aminophenol (PAP) is an important intermediate reagent in the synthesis of paracetamol, widely used as an analgesic and antipyretic drug. Therefore, finding an effective catalyst to improve PAP synthesis efficiency is worth studying. Among those studies, nanocomposite is the most promising material. In this study, Ag/GO nanocomposites were synthesized by reducing silver nitrate on graphene oxide (GO) with sodium borohydride as a reducing agent and characterized by SEM, EDX, XRD and UV–vis methods. The catalytic ability was investigated based on the hydrogenation reaction of p-nitrophenol (PNP). We successfully synthesized Ag/GO nanocomposite with relatively homogeneous distributions and similar particle sizes. The results showed that Ag/GO nanocomposite has an excellent catalytic activity with the yield of reduction reaction at 97%, 3 min. Moreover, this photocatalyst can easily be recovered and reused three times without any reaction efficiency reduction. We also successfully synthesized and crystallized PAP with high purity and the total yield of 45.82%. The results show that Ag/GO nanocomposite is an excellent catalyst for high-performance reactions with many useful properties, such as easily recovered and repetitive used. On top of that, Ag/GO nanocomposite is safe, less toxic and environmentally friendly.