We report the construction of a graphene/tourmaline/TiO2(G/T/TiO2)composite system with enhanced charge‐carrier separation,and therefore enhanced photocatalytic properties,based on tailoring the surface‐charged stat...We report the construction of a graphene/tourmaline/TiO2(G/T/TiO2)composite system with enhanced charge‐carrier separation,and therefore enhanced photocatalytic properties,based on tailoring the surface‐charged state of graphene and/or by introducing an external electric field arising from tourmaline.A simple two‐step hydrothermal method was used to synthesize G/T/TiO2composites and poly(diallyldimethylammonium chloride)‐G/T/TiO2composites.In the photocatalytic degradation of2‐propanol(IPA),the catalytic activity of the composite containing negatively charged graphene was higher than of the composite containing positively charged graphene.The highest acetone evolution rate(223?mol/h)was achieved using the ternary composite with the optimum composition,i.e.,G0.5/T5/TiO2(0.5wt%graphene and5wt%tourmaline).The involvement of tourmaline and graphene in the composite is believed to facilitate the separation and transportation of electrons and holes photogenerated in TiO2.This synergetic effect could account for the enhanced photocatalytic activity of the G/T/TiO2composite.A mechanistic study indicated that O2??radicals and holes were the main reactive oxygen species in photocatalytic degradation of IPA.展开更多
The mechanical properties and microstructures of Al_(2)O_(3)whiskers and graphene nano-platelets(GNPs)co-reinforced Cu-matrix composites were studied.Cu-matrix composites with a variation of GNPs amount were fabricate...The mechanical properties and microstructures of Al_(2)O_(3)whiskers and graphene nano-platelets(GNPs)co-reinforced Cu-matrix composites were studied.Cu-matrix composites with a variation of GNPs amount were fabricated by mechanical alloying followed by vacuum hot-pressing sintering and hot isostatic pressing.The Cu-matrix composite with 0.5 wt.%GNPs(GNPs-0.5)suggests a good interfacial bonding of both Cu/C and Cu/Al_(2)O_(3)interfaces.Both the hardness and compressive strength of Cu-matrix composites show a consistent tendency that firstly increases to a critical value and then decreases with increasing GNPs amount.It is suggested that the most possible strengthening mechanisms of both GNPs and Al_(2)O_(3)whisker working in the Cu-matrix composites involve energy dissipating and load transfer,as well as grain refinements for GNPs.The synergetic effect of GNPs and Al_(2)O_(3)whiskers is highlighted that the embedded GNPs would hinder the crack path generated at the Al_(2)O_(3)/Cu interface and enhance the already outstanding strengthening effect that Al_(2)O_(3)whiskers provide.展开更多
TiO2 nanocrystals/graphene （TiO2/GR） composite are prepared by combining flocculation and hydrothermal reduction technology using graphite oxide and TiO2 colloid as precursors. The obtained materials are examined by...TiO2 nanocrystals/graphene （TiO2/GR） composite are prepared by combining flocculation and hydrothermal reduction technology using graphite oxide and TiO2 colloid as precursors. The obtained materials are examined by scanning electron microscopy, transition electron microscopy, X-ray diffraction, N2 adsorption desorption, and ultraviolet-visible diffuse spectroscopy. The results suggest that the presence of TiO2 nanocrystals with diameter of about 15 nm prevents GR nanosheets from agglomeration. Owing to the uniform distribution of TiO2 nanocrystals on the GR nanosheets, TiO2/GR composite exhibits stronger light absorption in the visible region, higher adsorption capacity to methylene blue and higher efficiency of charge separation and transportation compared with pure TiO2. Moreover, the TiO2/GR composite with a GR content of 30% shows higher photocatalytic removal efficiency of MB from water than that of pure TiO2 and commercial P25 under both UV and sunlight irradiation.展开更多
Na–CO_(2) batteries recently are emerging as promising energy-storage devices due to the abundance of Na in the earth’s crust and the clean utilization of greenhouse gas CO_(2) .However,similar to metallic Li,metall...Na–CO_(2) batteries recently are emerging as promising energy-storage devices due to the abundance of Na in the earth’s crust and the clean utilization of greenhouse gas CO_(2) .However,similar to metallic Li,metallic Na also suffers from a serious issue of dendrite growth upon repeated cycling,while a facile method to solve this issue is still lacking.In this work,we report an effective,environmentally friendly method to inhibit Na dendrite growth by in situ constructing a stable,NaF-rich solid electrolyte interface(SEI)layer on metallic Na via adding a small amount(~3 wt%)of fluorinated graphene(FG)in bulk Na.Inspired by the forging processing,a uniform Na/FG composite was obtained by melting and repetitive FG-adsorbing/hammering processes.The Na/FG–Na/FG half cell exhibits a low voltage hysteresis of 110–140 mV over 700 h at a current density up to 5 mA cm^(-2) with an areal capacity as high as 5 mAh cm^(-2).Na–CO_(2) full cell with the Na/FG anode is able to sustain a stable cycling of 391 cycles at a limited capacity of 1000 mAh g^(-1).Long cycle life of the cell can be attributed to the protecting effect of the in situ fabricated NaF-rich SEI layer on metallic Na.Both experiments and density functional theory(DFT)calculations confirm the formation of the NaF-rich SEI layer.The inhibition effect of the NaF-rich SEI layer for Na dendrites is verified by in situ optical microscopy observations.展开更多
The main bottleneck against industrial utilization of sodium ion batteries(SIBs)is the lack of high-capacity electrodes to rival those of the benchmark lithium ion batteries(LIBs).Here in this work,we have developed a...The main bottleneck against industrial utilization of sodium ion batteries(SIBs)is the lack of high-capacity electrodes to rival those of the benchmark lithium ion batteries(LIBs).Here in this work,we have developed an economical method for in situ fabrication of nanocomposites made of crystalline few-layer graphene sheets loaded with ultrafine SnO_(2)nanocrystals,using short exposure of microwave to xerogel of graphene oxide(GO)and tin tetrachloride containing minute catalyzing dispersoids of chemically reduced GO(RGO).The resultant nanocomposites(SnO_(2)@MWG)enabled significantly quickened redox processes as SIB anode,which led to remarkable full anode-specific capacity reaching 538 mAh g^(−1)at 0.05 A g^(−1)(about 1.45 times of the theoretical capacity of graphite for the LIB),in addition to outstanding rate performance over prolonged charge–discharge cycling.Anodes based on the optimized SnO_(2)@MWG delivered stable performance over 2000 cycles even at a high current density of 5 A g^(−1),and capacity retention of over 70.4%was maintained at a high areal loading of 3.4 mg cm^(−2),highly desirable for high energy density SIBs to rival the current benchmark LIBs.展开更多
1 Introduction Supercapacitor also called electrochemical capacitor,has become one of the most promising energy storage devices due to its long service life,great power density,high energy density,green environmental ...1 Introduction Supercapacitor also called electrochemical capacitor,has become one of the most promising energy storage devices due to its long service life,great power density,high energy density,green environmental protection(Simon et al,2008;Ma et al,2013).Based on the charge storage mechanisms,Supercapacitors can be divided into展开更多
The nanometer MnO2 has outstanding electrochemical performance theoretically, but it is not suitable for actual utilization, which may result in capacity decrease and resource waste. In this study we have utilized the...The nanometer MnO2 has outstanding electrochemical performance theoretically, but it is not suitable for actual utilization, which may result in capacity decrease and resource waste. In this study we have utilized the characterizations of the nanometer material, synthesized a type of nanometer α-MnO2 through KMnO4 and KNO3 with hydrothermal method, and mixed the products into micron electrolytic manganese dioxide （EMD） to enhance the electrochemical performance of the electrode.The cyclic voltammogram and galvanostatical discharge measurements of the samples were investigated. It is found that the 50﹪ nanometer MnO2 mixed electrode has the best electrochemical performance. The electrochemical performance improvement mechanism of the sample nanometer MnO2 mixed into micron EMD was discussed. With the existence of electrolyte, the nanometer MnO2 particles filled into the interspaces of the micron EMD particles, the mass and charge transfer conditions of the electrode reaction were improved, and the electrode polarization was diminished.展开更多
A novel chemical technique combined with unique plasma activated sintering（PAS） was utilized to prepare consolidated copper matrix composites（CMCs） by adding Cu-SnO2-rGO layered micro powders as reinforced fillers...A novel chemical technique combined with unique plasma activated sintering（PAS） was utilized to prepare consolidated copper matrix composites（CMCs） by adding Cu-SnO2-rGO layered micro powders as reinforced fillers into Cu matrix. The repeating Cu-SnO2-rGO structure was composed of inner dispersed reduced graphene oxide（r GO）, SnO2 as intermedia and outer Cu coating. SnO2 was introduced to the surface of rGO sheets in order to prevent the graphene aggregation with SnO2 serving as spacer and to provide enough active sites for subsequent Cu deposition. This process can guarantee rGO sheets to suffi ciently disperse and Cu nanoparticles to tightly and uniformly anchor on each layer of rGO by means of the SnO2 active sites as well as strictly control the reduction speed of Cu^2＋. The complete cover of Cu nanoparticles on rGO sheets thoroughly avoids direct contact among rGO layers. Hence, the repeating structure can simultaneously solve the wettability problem between rGO and Cu matrix as well as improve the bonding strength between rGO and Cu matrix at the well-bonded Cu-SnO2-rGO interface. The isolated rGO can effectively hinder the glide of dislocation at Cu-rGO interface and support the applied loads. Finally, the compressive strength of CMCs was enhanced when the strengthening effi ciency reached up to 41.展开更多
This research work aims to reduce the band gap of thin layers of titanium oxide by the incorporation of graphene oxide sheets. Thin layers of the TiO2-GO composites were prepared on a glass substrate by the spin-coati...This research work aims to reduce the band gap of thin layers of titanium oxide by the incorporation of graphene oxide sheets. Thin layers of the TiO2-GO composites were prepared on a glass substrate by the spin-coating technique from GO and an aqueous solution of TiO2. A significant decrease in optical band gap was observed at the TiO2-GO compound compared to that of pure TiO2. Samples as prepared were characterized using XRD, SEM and UV-visible spectra. XRD analysis revealed the amorphous nature of the deposited layers. Scanning electron microscope reveals the dispersion of graphene nanofiles among titanium oxide nanoparticles distributed at the surface with an almost uniform size distribution. The band gap has been calculated and is around 2 eV after incorporation of Graphene oxide. The chemical bond C-Ti between the titanium oxide and graphene sheets is at the origin of this reduction.展开更多
The synthesis of graphene supported TiO2（b） nanosheets by a double hydrother- mal method for lithium storage was reported. The titanate nanosheets synthesized by the first hydrothermal progress and the graphene oxid...The synthesis of graphene supported TiO2（b） nanosheets by a double hydrother- mal method for lithium storage was reported. The titanate nanosheets synthesized by the first hydrothermal progress and the graphene oxide obtained by the oxidation of graphite were hydrothermally treated together to fabricate the TiO2（b）/graphene composite. The electrochemical measurements illustrate that the graphene supporter obviously improves the cyclic performance of TiO2（b）, which can be attributed to the better dispersion and the decrease of resistance for the TiO2（b） nanosheets in the composite.展开更多
In this study, a new facile preparation method of nanocomposites consisting of graphene oxide and manganese dioxide nanowires（GO/MnO2 NWs） was developed. The morphology, structure and composition of the resulted pro...In this study, a new facile preparation method of nanocomposites consisting of graphene oxide and manganese dioxide nanowires（GO/MnO2 NWs） was developed. The morphology, structure and composition of the resulted products were characterized by transmission electron microscopy, X-ray diffraction and N2 adsorption and desorption. The GO/MnO2 nanocomposite was used as an electrode material for non-enzymatic determination of hydrogen peroxide. The proposed sensor exhibits excellent electrocatalytic performance for the determination of hydrogen peroxide in phosphate buffer solution（PBS, pH7） at an applied potential of 0.75 V. The non-enzymatic biosensor for determination of hydrogen peroxide displayed a wide linear range of 4.90 mmol L^-1–4.50 mmol L^-1with a correlation coefficient of 0.9992, a low detection limit of 0.48 mmol L^-1 and a high sensitivity of 191.22μA（mmol L^-1）^-1cm^-2（signal/noise, S/N = 3）. Moreover, the non-enzymatic biosensor shows an excellent selectivity.展开更多
Graphene/hierarchy structure manganese dioxide （GN/MnO2） composites were synthesized using a simple microwave-hydrothermal method. The properties of the prepared composites were analyzed using field emission scannin...Graphene/hierarchy structure manganese dioxide （GN/MnO2） composites were synthesized using a simple microwave-hydrothermal method. The properties of the prepared composites were analyzed using field emission scanning electron microscopy （FE-SEM）, X-ray diffraction （XRD）, transmission electron microscopy （TEM）, and X-ray photoelectron spectroscopy （XPS） measurements. The electrochemical performances of the composites were analyzed using cyclic voltammetry, electrochemical impedance spectrometry （EIS）, and chronopotentiometry. The results showed that GN/MnO2 （10 wt% graphene） displayed a specific capacitance of 244 F/g at a current density of 100 mA/g. An excellent cyclic stability was obtained with a capacity retention of approximately 94.3% after 500 cycles in a 1 mol/L Li2SO4 solution. The improved electrochemical performance is attributed to the hierarchy structure of the manganese dioxide, which can enlarge the interface between the active materials and the electrolyte. The prepa- ration route provides a new approach for hierarchy structure graphene composites; this work could be readily extended to the preparation of other graphene-based composites with different structures for use in energy storage devices.展开更多
A λ-MnO2 supported Pt nanocatalyst（5 wt.% Pt/λ-MnO2） was synthesized using a facile approach.X-ray diffraction（XRD）, X-ray photoelectron spectroscopy（XPS）, scanning electronic microscope（SEM）, transmission e...A λ-MnO2 supported Pt nanocatalyst（5 wt.% Pt/λ-MnO2） was synthesized using a facile approach.X-ray diffraction（XRD）, X-ray photoelectron spectroscopy（XPS）, scanning electronic microscope（SEM）, transmission electron microscopy（TEM）, and energy disperse spectroscopy（EDS） were used for catalyst structure and morphology characterization, which showed that the metallic Pt particles were attached on a λ-MnO2 surface through the interaction between Pt and λ-MnO2.Cyclic voltammetry（CV） was used to test the catalytic activity of Pt/λ-MnO2 toward methanol oxidation, which showed that Pt/λ-MnO2 catalyst has much higher catalytic activity than baseline Pt/C catalyst.展开更多
基金supported by the National Basic Research Program of China (973 Program,2014CB239300)the National Natural Science Foundation of China (51572191)the Natural Science Foundation of Tianjin (13JCYBJC16600)~~
文摘We report the construction of a graphene/tourmaline/TiO2(G/T/TiO2)composite system with enhanced charge‐carrier separation,and therefore enhanced photocatalytic properties,based on tailoring the surface‐charged state of graphene and/or by introducing an external electric field arising from tourmaline.A simple two‐step hydrothermal method was used to synthesize G/T/TiO2composites and poly(diallyldimethylammonium chloride)‐G/T/TiO2composites.In the photocatalytic degradation of2‐propanol(IPA),the catalytic activity of the composite containing negatively charged graphene was higher than of the composite containing positively charged graphene.The highest acetone evolution rate(223?mol/h)was achieved using the ternary composite with the optimum composition,i.e.,G0.5/T5/TiO2(0.5wt%graphene and5wt%tourmaline).The involvement of tourmaline and graphene in the composite is believed to facilitate the separation and transportation of electrons and holes photogenerated in TiO2.This synergetic effect could account for the enhanced photocatalytic activity of the G/T/TiO2composite.A mechanistic study indicated that O2??radicals and holes were the main reactive oxygen species in photocatalytic degradation of IPA.
基金the financial supports from the National Natural Science Foundation of China (No. 52101183)China Postdoctoral Science Foundation (Nos. 2017M623054, 2018T110993)
文摘The mechanical properties and microstructures of Al_(2)O_(3)whiskers and graphene nano-platelets(GNPs)co-reinforced Cu-matrix composites were studied.Cu-matrix composites with a variation of GNPs amount were fabricated by mechanical alloying followed by vacuum hot-pressing sintering and hot isostatic pressing.The Cu-matrix composite with 0.5 wt.%GNPs(GNPs-0.5)suggests a good interfacial bonding of both Cu/C and Cu/Al_(2)O_(3)interfaces.Both the hardness and compressive strength of Cu-matrix composites show a consistent tendency that firstly increases to a critical value and then decreases with increasing GNPs amount.It is suggested that the most possible strengthening mechanisms of both GNPs and Al_(2)O_(3)whisker working in the Cu-matrix composites involve energy dissipating and load transfer,as well as grain refinements for GNPs.The synergetic effect of GNPs and Al_(2)O_(3)whiskers is highlighted that the embedded GNPs would hinder the crack path generated at the Al_(2)O_(3)/Cu interface and enhance the already outstanding strengthening effect that Al_(2)O_(3)whiskers provide.
文摘TiO2 nanocrystals/graphene （TiO2/GR） composite are prepared by combining flocculation and hydrothermal reduction technology using graphite oxide and TiO2 colloid as precursors. The obtained materials are examined by scanning electron microscopy, transition electron microscopy, X-ray diffraction, N2 adsorption desorption, and ultraviolet-visible diffuse spectroscopy. The results suggest that the presence of TiO2 nanocrystals with diameter of about 15 nm prevents GR nanosheets from agglomeration. Owing to the uniform distribution of TiO2 nanocrystals on the GR nanosheets, TiO2/GR composite exhibits stronger light absorption in the visible region, higher adsorption capacity to methylene blue and higher efficiency of charge separation and transportation compared with pure TiO2. Moreover, the TiO2/GR composite with a GR content of 30% shows higher photocatalytic removal efficiency of MB from water than that of pure TiO2 and commercial P25 under both UV and sunlight irradiation.
基金supported by the National Natural Science Foundation of China(No.51572238)Zhejiang Provincial Natural Science Foundation of China under Grant no.LY19E020013Hunan Provincial Science and Technology Major Project of China(2020GK1014).
文摘Na–CO_(2) batteries recently are emerging as promising energy-storage devices due to the abundance of Na in the earth’s crust and the clean utilization of greenhouse gas CO_(2) .However,similar to metallic Li,metallic Na also suffers from a serious issue of dendrite growth upon repeated cycling,while a facile method to solve this issue is still lacking.In this work,we report an effective,environmentally friendly method to inhibit Na dendrite growth by in situ constructing a stable,NaF-rich solid electrolyte interface(SEI)layer on metallic Na via adding a small amount(~3 wt%)of fluorinated graphene(FG)in bulk Na.Inspired by the forging processing,a uniform Na/FG composite was obtained by melting and repetitive FG-adsorbing/hammering processes.The Na/FG–Na/FG half cell exhibits a low voltage hysteresis of 110–140 mV over 700 h at a current density up to 5 mA cm^(-2) with an areal capacity as high as 5 mAh cm^(-2).Na–CO_(2) full cell with the Na/FG anode is able to sustain a stable cycling of 391 cycles at a limited capacity of 1000 mAh g^(-1).Long cycle life of the cell can be attributed to the protecting effect of the in situ fabricated NaF-rich SEI layer on metallic Na.Both experiments and density functional theory(DFT)calculations confirm the formation of the NaF-rich SEI layer.The inhibition effect of the NaF-rich SEI layer for Na dendrites is verified by in situ optical microscopy observations.
基金funded by the Zhengzhou Materials Genome Institute,the National Talents Program of China,and Key Innovation Projects of the Zhengzhou Municipal City of China.
文摘The main bottleneck against industrial utilization of sodium ion batteries(SIBs)is the lack of high-capacity electrodes to rival those of the benchmark lithium ion batteries(LIBs).Here in this work,we have developed an economical method for in situ fabrication of nanocomposites made of crystalline few-layer graphene sheets loaded with ultrafine SnO_(2)nanocrystals,using short exposure of microwave to xerogel of graphene oxide(GO)and tin tetrachloride containing minute catalyzing dispersoids of chemically reduced GO(RGO).The resultant nanocomposites(SnO_(2)@MWG)enabled significantly quickened redox processes as SIB anode,which led to remarkable full anode-specific capacity reaching 538 mAh g^(−1)at 0.05 A g^(−1)(about 1.45 times of the theoretical capacity of graphite for the LIB),in addition to outstanding rate performance over prolonged charge–discharge cycling.Anodes based on the optimized SnO_(2)@MWG delivered stable performance over 2000 cycles even at a high current density of 5 A g^(−1),and capacity retention of over 70.4%was maintained at a high areal loading of 3.4 mg cm^(−2),highly desirable for high energy density SIBs to rival the current benchmark LIBs.
基金financial support from the National Natural Science Foundation of China(51274015)National Program on Key Basic Research Project (973 Program) (2014CB846000)Test Fund of Peking University
文摘1 Introduction Supercapacitor also called electrochemical capacitor,has become one of the most promising energy storage devices due to its long service life,great power density,high energy density,green environmental protection(Simon et al,2008;Ma et al,2013).Based on the charge storage mechanisms,Supercapacitors can be divided into
基金This paper is supported by Chenguang Program for Young Scientists of Wuhan, Hubei Province (No. 20065004116-22).
文摘The nanometer MnO2 has outstanding electrochemical performance theoretically, but it is not suitable for actual utilization, which may result in capacity decrease and resource waste. In this study we have utilized the characterizations of the nanometer material, synthesized a type of nanometer α-MnO2 through KMnO4 and KNO3 with hydrothermal method, and mixed the products into micron electrolytic manganese dioxide （EMD） to enhance the electrochemical performance of the electrode.The cyclic voltammogram and galvanostatical discharge measurements of the samples were investigated. It is found that the 50﹪ nanometer MnO2 mixed electrode has the best electrochemical performance. The electrochemical performance improvement mechanism of the sample nanometer MnO2 mixed into micron EMD was discussed. With the existence of electrolyte, the nanometer MnO2 particles filled into the interspaces of the micron EMD particles, the mass and charge transfer conditions of the electrode reaction were improved, and the electrode polarization was diminished.
基金Funded by the National Natural Science Foundation of China(51572208)the 111 Project(B13035)+1 种基金the National Natural Science Foundation of Hubei Province(2014CFB257 and 2014CFB258)the Fundamental Research Funds for the Central Universities(WUT:2015-III-059)
文摘A novel chemical technique combined with unique plasma activated sintering（PAS） was utilized to prepare consolidated copper matrix composites（CMCs） by adding Cu-SnO2-rGO layered micro powders as reinforced fillers into Cu matrix. The repeating Cu-SnO2-rGO structure was composed of inner dispersed reduced graphene oxide（r GO）, SnO2 as intermedia and outer Cu coating. SnO2 was introduced to the surface of rGO sheets in order to prevent the graphene aggregation with SnO2 serving as spacer and to provide enough active sites for subsequent Cu deposition. This process can guarantee rGO sheets to suffi ciently disperse and Cu nanoparticles to tightly and uniformly anchor on each layer of rGO by means of the SnO2 active sites as well as strictly control the reduction speed of Cu^2＋. The complete cover of Cu nanoparticles on rGO sheets thoroughly avoids direct contact among rGO layers. Hence, the repeating structure can simultaneously solve the wettability problem between rGO and Cu matrix as well as improve the bonding strength between rGO and Cu matrix at the well-bonded Cu-SnO2-rGO interface. The isolated rGO can effectively hinder the glide of dislocation at Cu-rGO interface and support the applied loads. Finally, the compressive strength of CMCs was enhanced when the strengthening effi ciency reached up to 41.
文摘This research work aims to reduce the band gap of thin layers of titanium oxide by the incorporation of graphene oxide sheets. Thin layers of the TiO2-GO composites were prepared on a glass substrate by the spin-coating technique from GO and an aqueous solution of TiO2. A significant decrease in optical band gap was observed at the TiO2-GO compound compared to that of pure TiO2. Samples as prepared were characterized using XRD, SEM and UV-visible spectra. XRD analysis revealed the amorphous nature of the deposited layers. Scanning electron microscope reveals the dispersion of graphene nanofiles among titanium oxide nanoparticles distributed at the surface with an almost uniform size distribution. The band gap has been calculated and is around 2 eV after incorporation of Graphene oxide. The chemical bond C-Ti between the titanium oxide and graphene sheets is at the origin of this reduction.
基金supported by the Natural Science Foundation of Fujian Province(No.2013J05027)
文摘The synthesis of graphene supported TiO2（b） nanosheets by a double hydrother- mal method for lithium storage was reported. The titanate nanosheets synthesized by the first hydrothermal progress and the graphene oxide obtained by the oxidation of graphite were hydrothermally treated together to fabricate the TiO2（b）/graphene composite. The electrochemical measurements illustrate that the graphene supporter obviously improves the cyclic performance of TiO2（b）, which can be attributed to the better dispersion and the decrease of resistance for the TiO2（b） nanosheets in the composite.
基金financially supported by the National Natural Science Foundation of China (No. 21273080)Guangdong Natural Science Foundation (No. 2014A030311039)
文摘In this study, a new facile preparation method of nanocomposites consisting of graphene oxide and manganese dioxide nanowires（GO/MnO2 NWs） was developed. The morphology, structure and composition of the resulted products were characterized by transmission electron microscopy, X-ray diffraction and N2 adsorption and desorption. The GO/MnO2 nanocomposite was used as an electrode material for non-enzymatic determination of hydrogen peroxide. The proposed sensor exhibits excellent electrocatalytic performance for the determination of hydrogen peroxide in phosphate buffer solution（PBS, pH7） at an applied potential of 0.75 V. The non-enzymatic biosensor for determination of hydrogen peroxide displayed a wide linear range of 4.90 mmol L^-1–4.50 mmol L^-1with a correlation coefficient of 0.9992, a low detection limit of 0.48 mmol L^-1 and a high sensitivity of 191.22μA（mmol L^-1）^-1cm^-2（signal/noise, S/N = 3）. Moreover, the non-enzymatic biosensor shows an excellent selectivity.
基金supported by the Program for New Century Excellent Talents in University(NCET-09-0215)by a grant from the National Research and Development Program of China (863 Program,2012AA110302)by the State Key Laboratory of Multiphase Complex Systems(MPCS-2011-D-08)
文摘Graphene/hierarchy structure manganese dioxide （GN/MnO2） composites were synthesized using a simple microwave-hydrothermal method. The properties of the prepared composites were analyzed using field emission scanning electron microscopy （FE-SEM）, X-ray diffraction （XRD）, transmission electron microscopy （TEM）, and X-ray photoelectron spectroscopy （XPS） measurements. The electrochemical performances of the composites were analyzed using cyclic voltammetry, electrochemical impedance spectrometry （EIS）, and chronopotentiometry. The results showed that GN/MnO2 （10 wt% graphene） displayed a specific capacitance of 244 F/g at a current density of 100 mA/g. An excellent cyclic stability was obtained with a capacity retention of approximately 94.3% after 500 cycles in a 1 mol/L Li2SO4 solution. The improved electrochemical performance is attributed to the hierarchy structure of the manganese dioxide, which can enlarge the interface between the active materials and the electrolyte. The prepa- ration route provides a new approach for hierarchy structure graphene composites; this work could be readily extended to the preparation of other graphene-based composites with different structures for use in energy storage devices.
基金supported by the Funding Project for Academic Human Resources Development in Institutions of Higher Learning under the Jurisdiction of Beijing Municipality, Beijing Natural Science Foundation (No. 207001)the Major State Basic Research and Development Program of China (No. 2002CB211807)
文摘A λ-MnO2 supported Pt nanocatalyst（5 wt.% Pt/λ-MnO2） was synthesized using a facile approach.X-ray diffraction（XRD）, X-ray photoelectron spectroscopy（XPS）, scanning electronic microscope（SEM）, transmission electron microscopy（TEM）, and energy disperse spectroscopy（EDS） were used for catalyst structure and morphology characterization, which showed that the metallic Pt particles were attached on a λ-MnO2 surface through the interaction between Pt and λ-MnO2.Cyclic voltammetry（CV） was used to test the catalytic activity of Pt/λ-MnO2 toward methanol oxidation, which showed that Pt/λ-MnO2 catalyst has much higher catalytic activity than baseline Pt/C catalyst.
