Over the span of years, improvements over various synthesis methods of graphene are constantly pursued to provide safer and more effective alternatives. Though the extraction of graphene through Hummers method is one ...Over the span of years, improvements over various synthesis methods of graphene are constantly pursued to provide safer and more effective alternatives. Though the extraction of graphene through Hummers method is one of the oldest techniques yet it is one of the most suitable methods for the formation of bulk graphene. Graphene can be obtained in the form of reduced Graphite oxide, sometimes also referred as Graphene oxide. The effectiveness of this oxidation process can be evaluated by the magnitude of carbon/oxygen ratio of the obtained graphene. Here, graphene oxide (GO) was prepared by oxidizing the purified natural flake graphite (NFG) by a modified Hummers method. The attempts have been made to synthesize GO having few layers by using a modified Hummers method where the amount of NaNO3 has been decreased, and the amount of KMnO4 is increased. The reaction has been performed in a 9:1 (by volume) mixture of H2SO4/H3PO4. This modification is successful in increasing the reaction yield and reducing the toxic gas evolution while using a varied proportion of KMnO4 and H2SO4 as those required by Hummers method. A new component of K2S2O8 has been introduced to the reaction system to maintain the pH value. Reduced graphene oxide (rGO) was thereafter extracted by thermal modification of GO. Here, GO has been used as a precursor for graphene synthesis by thermal reduction processes. The results of FTIR and Raman spectroscopy analysis show that the NFG when oxidized by strong oxidants like KMnO4 and NaNO3, introduced oxygen atoms into the graphite layers and formed bonds like C=O, C-H, COOH and C-O-C with the carbon atoms in the graphite layers. The structure and morphology of both GO and rGO were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy, Raman spectroscopy, Brunauer-Emmett-Teller (BET) surface area analysis and differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).展开更多
The modified Hummers method was employed to generate graphene oxide,and Ag /reduced graphene oxide (RGO) nanocomposites were synthesized at different temperatures by using sodium citrate as the reductant. Scanning ele...The modified Hummers method was employed to generate graphene oxide,and Ag /reduced graphene oxide (RGO) nanocomposites were synthesized at different temperatures by using sodium citrate as the reductant. Scanning electron microscopy (SEM),transmission electron microscopy (TEM),X-ray diffraction (XRD),X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy were employed to characterize the reaction products. The results indicate that RGO has been synthesized successfully,and Ag particles are distributed evenly on the surface of RGO.The RGO prepared at a reaction temperature of 120℃ shows the best surface-enhanced Raman scattering (SERS) activity.The Ag /RGO nanocomposites modified by 10^- 5 mol /L 4-aminothiophenol (PATP) successfully detect a 10^- 5 mol /L 2,4,6-trinitrotoluene (TNT) alcohol solution.展开更多
Iron disulfide is considered to be a potential anode material for sodium-ion batteries due to its high theoretical capacity. However, its applications are seriously limited by the weak conductivity and large volume ch...Iron disulfide is considered to be a potential anode material for sodium-ion batteries due to its high theoretical capacity. However, its applications are seriously limited by the weak conductivity and large volume change, which results in low reversible capacity and poor cycling stability.Herein, reduced graphene oxide-wrapped FeS_2(FeS_2/rGO)composite was fabricated to achieve excellent electrochemical performance via a facile two-step method. The introduction of rGO effectively improved the conductivity,BET surface area, and structural stability of the FeS_2 active material, thus endowing it with high specific capacity, good rate capability, as well as excellent cycling stability. Electrochemical measurements show that the FeS_2/rGO composite had a high initial discharge capacity of 1263.2 mAh gg^(-1) at 100 mA gg^(-1) and a high discharge capacity of 344 mAh gg^(-1) at 10 A gg^(-1), demonstrating superior rate performance. After 100 cycles at 100 mA gg^(-1),the discharge capacity remained at 609.5 mAh g^(-1), indicating the excellent cycling stability of the FeS_2/rGO electrode.展开更多
The optimization of the scaffolds to provide a suitable matrix and accelerate the regeneration process is vital for bone tissue engineering.However,poor mechanical and biological characteristics remain the primary cha...The optimization of the scaffolds to provide a suitable matrix and accelerate the regeneration process is vital for bone tissue engineering.However,poor mechanical and biological characteristics remain the primary challenges that must be addressed.For example,although bredigite(Br)has shown great potential for application in bone tissue engineering,it easily fails in replacement.In the present work,these challenges are addressed by reinforcing the Br matrix with nanosheets of graphene oxide(rGO)that have been reduced by bovine serum albumin(BSA)in order to enhance the mechanical properties and biological behavior.The reduction of graphene oxide by BSA improves the water stability of the nanosheets and provides an electrostatic interaction between theBSA-rGO nanosheets and theBr particles.The high thermal conductivity of theBSA-rGO nanosheets decreases the porosity of the Br by transferring heat to the core of the tablet.Furthermore,the addition of BSA-rGO nanosheets into the Br matrix enhances the adhesion of G-292 cells on the surface of the tablets.These findings suggest that the tablet consisting of BSA-rGO-reinforced Br has encouraging potential for application in bone tissue engineering.展开更多
An electrochemical biosensing platform was developed based on glucose oxidase(GOx)/Fe3O4-reduced graphene oxide(Fe3O4-RGO) nanosheets loaded on the magnetic glassy carbon electrode(MGCE).With the advantages of the mag...An electrochemical biosensing platform was developed based on glucose oxidase(GOx)/Fe3O4-reduced graphene oxide(Fe3O4-RGO) nanosheets loaded on the magnetic glassy carbon electrode(MGCE).With the advantages of the magnetism, conductivity and biocompatibility of the Fe3O4-RGO nanosheets, the nanocomposites could be facilely adhered to the electrode surface by magnetically controllable assembling and beneficial to achieve the direct redox reactions and electrocatalytic behaviors of GOx immobilized into the nanocomposites. The biosensor exhibited good electrocatalytic activity, high sensitivity and stability. The current response is linear over glucose concentration ranging from 0.05 to 1.5 m M with a low detection limit of0.15 μM. Meanwhile, validation of the applicability of the biosensor was carried out by determining glucose in serum samples. The proposed protocol is simple, inexpensive and convenient, which shows great potential in biosensing application.展开更多
Micro Electro Mechanical Systems (MEMS) vector sensor is a recent advancement in the field of underwater acoustic sensors. The major incentive provided by this acoustic vector sensor is that it provides information ab...Micro Electro Mechanical Systems (MEMS) vector sensor is a recent advancement in the field of underwater acoustic sensors. The major incentive provided by this acoustic vector sensor is that it provides information about the direction of the incoming acoustic source signal in addition to the measurement of the pressure associated with the acoustic signal. We are reporting a design of a MEMS acoustic vector sensor for underwater applications using piezoresistive film of Reduced Graphine Oxide (RGO), realized on kapton (polyimide) film as the starting material. The sensor is designed and fabricated by deposition of RGO on a kapton, which is a flexible substrate by the method of drop casting making the process simple, low-cost and scalable. The application of the piezoresistive transduction principle and ingenious structure of the vector sensor based on bionic principle improves miniaturization and the low-frequency sensitivity. The fabricated sensor shows a repeatable response in both static and dynamic conditions, to the applied strain due to the acoustic signal in a given direction. The experimental results show that fabricated sensor based on MEMS technology and piezoresistive effect is feasible and it possesses intrinsic two-dimensional directivity. The fabricated device has given good response for the low-frequency acoustic signals due to the effect of piezoresistive transduction principle and the resonance frequency of the device is found to be around 80 Hz with the displacement sensitivity around 3 mV/mm and 2 mV/mm of X and Y axis directions respectively.展开更多
In situ carbon-coated Co_(3)Se_(4)/CoSe_(2)(Co_(x)Se_(y))nanoparticles(NPs)attached on three-dimensional(3D)reduced graphene oxide(rGO)sheets were skillfully developed in this work,which involved the environment-frien...In situ carbon-coated Co_(3)Se_(4)/CoSe_(2)(Co_(x)Se_(y))nanoparticles(NPs)attached on three-dimensional(3D)reduced graphene oxide(rGO)sheets were skillfully developed in this work,which involved the environment-friendly hydrothermal method,freeze drying,and selenide calcination.Within the structure,the glucose-derived carbon layer exhibited significantly homogeneous dispersion under an argon environment.This structure not only has enhanced stability,but also can effectively mitigate the volume swell of Co_(x)Se_(y) particles.The resulted Co_(3)Sea/CoSe_(2)@C/rGO(CSe@C/rGO)exhibited a specific surface area(SSA)of 240.9 m^(2)·g^(-1),offering more electrochemically active sites for the storage of energy related to lithium ions.The rGO matrix held exceptional flexibility and functional structural rigidity,facilitating the swift ion intercalation and ensuring the high conductivity and recyclability of the structure.When applied to anodes designed for lithium-ion batteries(LiBs),this material demonstrated distinguished rate and ultra-high reversible capacity(872.98 mA·h·g^(-1) at 0.5 A·g^(-1)).Meanwhile,its capacity retention reached 119.5%after 500 cycles at 2 A·g^(-1),with a coulombic efficiency of 100%.This work potentially paves the way for generating fast and powerful metal selenide anodes and initiating LiBs with good performance.展开更多
以水杨酸为模板剂和还原剂,采用水热法制备得到了一种MoO3纳米带/RGO复合材料。利用XRD、SEM、TEM、拉曼光谱、恒流充放电、交流阻抗等手段对样品的结构、形貌以及电化学性能进行表征。测试结果表明,MoO3纳米带/RGO复合材料作为锂离子...以水杨酸为模板剂和还原剂,采用水热法制备得到了一种MoO3纳米带/RGO复合材料。利用XRD、SEM、TEM、拉曼光谱、恒流充放电、交流阻抗等手段对样品的结构、形貌以及电化学性能进行表征。测试结果表明,MoO3纳米带/RGO复合材料作为锂离子电池负极材料,在50 m A·g-1的电流密度下可逆比容量为1 000 m Ah·g-1,循环50次后比容量还保持在950 m Ah·g-1,相比于MoO3纳米带其容量保持能力和循环性能得到了显著改善。展开更多
A kind of sandwich-like NiCo_2O_4/rGO/NiO heterostructure composite has been successfully anchored on nickel foam substrate via a three-step hydrothermal method with successive annealing treatment. The smart combinati...A kind of sandwich-like NiCo_2O_4/rGO/NiO heterostructure composite has been successfully anchored on nickel foam substrate via a three-step hydrothermal method with successive annealing treatment. The smart combination of NiCo_2O_4, reduced graphene oxide(rGO), and NiO nanostructure in the sandwich-like nano architecture shows a promising synergistic effect for supercapacitors with greatly enhanced electrochemical performance. For serving as supercapacitor electrode, the NiCo_2O_4/rGO/NiO heterostructure materials exhibit remarkable specific capacitance of 2644 mF cm^(-2)at current density of 1 mA cm^(-2),and excellent capacitance retentions of 97.5% after 3000 cycles. It is expected that the present heterostructure will be a promising electrode material for high-performance supercapacitors.展开更多
文摘Over the span of years, improvements over various synthesis methods of graphene are constantly pursued to provide safer and more effective alternatives. Though the extraction of graphene through Hummers method is one of the oldest techniques yet it is one of the most suitable methods for the formation of bulk graphene. Graphene can be obtained in the form of reduced Graphite oxide, sometimes also referred as Graphene oxide. The effectiveness of this oxidation process can be evaluated by the magnitude of carbon/oxygen ratio of the obtained graphene. Here, graphene oxide (GO) was prepared by oxidizing the purified natural flake graphite (NFG) by a modified Hummers method. The attempts have been made to synthesize GO having few layers by using a modified Hummers method where the amount of NaNO3 has been decreased, and the amount of KMnO4 is increased. The reaction has been performed in a 9:1 (by volume) mixture of H2SO4/H3PO4. This modification is successful in increasing the reaction yield and reducing the toxic gas evolution while using a varied proportion of KMnO4 and H2SO4 as those required by Hummers method. A new component of K2S2O8 has been introduced to the reaction system to maintain the pH value. Reduced graphene oxide (rGO) was thereafter extracted by thermal modification of GO. Here, GO has been used as a precursor for graphene synthesis by thermal reduction processes. The results of FTIR and Raman spectroscopy analysis show that the NFG when oxidized by strong oxidants like KMnO4 and NaNO3, introduced oxygen atoms into the graphite layers and formed bonds like C=O, C-H, COOH and C-O-C with the carbon atoms in the graphite layers. The structure and morphology of both GO and rGO were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy, Raman spectroscopy, Brunauer-Emmett-Teller (BET) surface area analysis and differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).
基金Beijing Higher Education Young Elite Teacher Project(YETP0499)
文摘The modified Hummers method was employed to generate graphene oxide,and Ag /reduced graphene oxide (RGO) nanocomposites were synthesized at different temperatures by using sodium citrate as the reductant. Scanning electron microscopy (SEM),transmission electron microscopy (TEM),X-ray diffraction (XRD),X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy were employed to characterize the reaction products. The results indicate that RGO has been synthesized successfully,and Ag particles are distributed evenly on the surface of RGO.The RGO prepared at a reaction temperature of 120℃ shows the best surface-enhanced Raman scattering (SERS) activity.The Ag /RGO nanocomposites modified by 10^- 5 mol /L 4-aminothiophenol (PATP) successfully detect a 10^- 5 mol /L 2,4,6-trinitrotoluene (TNT) alcohol solution.
基金supported by National Natural Science Foundation of China (51702138, 51702079)Natural Science Foundation of Jiangsu Province (BK20160213)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Iron disulfide is considered to be a potential anode material for sodium-ion batteries due to its high theoretical capacity. However, its applications are seriously limited by the weak conductivity and large volume change, which results in low reversible capacity and poor cycling stability.Herein, reduced graphene oxide-wrapped FeS_2(FeS_2/rGO)composite was fabricated to achieve excellent electrochemical performance via a facile two-step method. The introduction of rGO effectively improved the conductivity,BET surface area, and structural stability of the FeS_2 active material, thus endowing it with high specific capacity, good rate capability, as well as excellent cycling stability. Electrochemical measurements show that the FeS_2/rGO composite had a high initial discharge capacity of 1263.2 mAh gg^(-1) at 100 mA gg^(-1) and a high discharge capacity of 344 mAh gg^(-1) at 10 A gg^(-1), demonstrating superior rate performance. After 100 cycles at 100 mA gg^(-1),the discharge capacity remained at 609.5 mAh g^(-1), indicating the excellent cycling stability of the FeS_2/rGO electrode.
基金Thiswork is financially supported by IranUniversity of Science and Technology(IUST)and Motamed Cancer Institute(ACECR).
文摘The optimization of the scaffolds to provide a suitable matrix and accelerate the regeneration process is vital for bone tissue engineering.However,poor mechanical and biological characteristics remain the primary challenges that must be addressed.For example,although bredigite(Br)has shown great potential for application in bone tissue engineering,it easily fails in replacement.In the present work,these challenges are addressed by reinforcing the Br matrix with nanosheets of graphene oxide(rGO)that have been reduced by bovine serum albumin(BSA)in order to enhance the mechanical properties and biological behavior.The reduction of graphene oxide by BSA improves the water stability of the nanosheets and provides an electrostatic interaction between theBSA-rGO nanosheets and theBr particles.The high thermal conductivity of theBSA-rGO nanosheets decreases the porosity of the Br by transferring heat to the core of the tablet.Furthermore,the addition of BSA-rGO nanosheets into the Br matrix enhances the adhesion of G-292 cells on the surface of the tablets.These findings suggest that the tablet consisting of BSA-rGO-reinforced Br has encouraging potential for application in bone tissue engineering.
基金supported by the National Natural Science Foundation of China (21373138)Shanghai Sci. & Tech. Committee (12JC1407200)Program for Changjiang Scholars and Innovative Research Team in University (IRT1269)
文摘An electrochemical biosensing platform was developed based on glucose oxidase(GOx)/Fe3O4-reduced graphene oxide(Fe3O4-RGO) nanosheets loaded on the magnetic glassy carbon electrode(MGCE).With the advantages of the magnetism, conductivity and biocompatibility of the Fe3O4-RGO nanosheets, the nanocomposites could be facilely adhered to the electrode surface by magnetically controllable assembling and beneficial to achieve the direct redox reactions and electrocatalytic behaviors of GOx immobilized into the nanocomposites. The biosensor exhibited good electrocatalytic activity, high sensitivity and stability. The current response is linear over glucose concentration ranging from 0.05 to 1.5 m M with a low detection limit of0.15 μM. Meanwhile, validation of the applicability of the biosensor was carried out by determining glucose in serum samples. The proposed protocol is simple, inexpensive and convenient, which shows great potential in biosensing application.
文摘Micro Electro Mechanical Systems (MEMS) vector sensor is a recent advancement in the field of underwater acoustic sensors. The major incentive provided by this acoustic vector sensor is that it provides information about the direction of the incoming acoustic source signal in addition to the measurement of the pressure associated with the acoustic signal. We are reporting a design of a MEMS acoustic vector sensor for underwater applications using piezoresistive film of Reduced Graphine Oxide (RGO), realized on kapton (polyimide) film as the starting material. The sensor is designed and fabricated by deposition of RGO on a kapton, which is a flexible substrate by the method of drop casting making the process simple, low-cost and scalable. The application of the piezoresistive transduction principle and ingenious structure of the vector sensor based on bionic principle improves miniaturization and the low-frequency sensitivity. The fabricated sensor shows a repeatable response in both static and dynamic conditions, to the applied strain due to the acoustic signal in a given direction. The experimental results show that fabricated sensor based on MEMS technology and piezoresistive effect is feasible and it possesses intrinsic two-dimensional directivity. The fabricated device has given good response for the low-frequency acoustic signals due to the effect of piezoresistive transduction principle and the resonance frequency of the device is found to be around 80 Hz with the displacement sensitivity around 3 mV/mm and 2 mV/mm of X and Y axis directions respectively.
基金support from the National Natural Science Foundation of China(52071192)the Basic Research Project Fund of Shanxi Province(20210302124491 and 20210302123341)+5 种基金the Key Research and Development Project of Datong(2023003)the Basic Research Project Fund of Shanxi Datong University(2022K10 and 2022K11)the Graduate Education Reform project of Shanxi Datong University(21JG25)the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(2021L370)the Graduate Student Education Innovation Project of Shanxi Datong University(23CX25,22CX11,and 22CX20)the Doctoral Research Fund of Shanxi Datong University(2016-B-14,2016-B-20,and 2019-B-11).
文摘In situ carbon-coated Co_(3)Se_(4)/CoSe_(2)(Co_(x)Se_(y))nanoparticles(NPs)attached on three-dimensional(3D)reduced graphene oxide(rGO)sheets were skillfully developed in this work,which involved the environment-friendly hydrothermal method,freeze drying,and selenide calcination.Within the structure,the glucose-derived carbon layer exhibited significantly homogeneous dispersion under an argon environment.This structure not only has enhanced stability,but also can effectively mitigate the volume swell of Co_(x)Se_(y) particles.The resulted Co_(3)Sea/CoSe_(2)@C/rGO(CSe@C/rGO)exhibited a specific surface area(SSA)of 240.9 m^(2)·g^(-1),offering more electrochemically active sites for the storage of energy related to lithium ions.The rGO matrix held exceptional flexibility and functional structural rigidity,facilitating the swift ion intercalation and ensuring the high conductivity and recyclability of the structure.When applied to anodes designed for lithium-ion batteries(LiBs),this material demonstrated distinguished rate and ultra-high reversible capacity(872.98 mA·h·g^(-1) at 0.5 A·g^(-1)).Meanwhile,its capacity retention reached 119.5%after 500 cycles at 2 A·g^(-1),with a coulombic efficiency of 100%.This work potentially paves the way for generating fast and powerful metal selenide anodes and initiating LiBs with good performance.
文摘以水杨酸为模板剂和还原剂,采用水热法制备得到了一种MoO3纳米带/RGO复合材料。利用XRD、SEM、TEM、拉曼光谱、恒流充放电、交流阻抗等手段对样品的结构、形貌以及电化学性能进行表征。测试结果表明,MoO3纳米带/RGO复合材料作为锂离子电池负极材料,在50 m A·g-1的电流密度下可逆比容量为1 000 m Ah·g-1,循环50次后比容量还保持在950 m Ah·g-1,相比于MoO3纳米带其容量保持能力和循环性能得到了显著改善。
基金supported by the Special Fund for the Development of Strategic Emerging Industries of Shenzhen City of China(No.JCYJ20140419141154246)the National Nature Science Foundation of China(No.11174227)Chinese Universities Scientific Fund
文摘A kind of sandwich-like NiCo_2O_4/rGO/NiO heterostructure composite has been successfully anchored on nickel foam substrate via a three-step hydrothermal method with successive annealing treatment. The smart combination of NiCo_2O_4, reduced graphene oxide(rGO), and NiO nanostructure in the sandwich-like nano architecture shows a promising synergistic effect for supercapacitors with greatly enhanced electrochemical performance. For serving as supercapacitor electrode, the NiCo_2O_4/rGO/NiO heterostructure materials exhibit remarkable specific capacitance of 2644 mF cm^(-2)at current density of 1 mA cm^(-2),and excellent capacitance retentions of 97.5% after 3000 cycles. It is expected that the present heterostructure will be a promising electrode material for high-performance supercapacitors.
