| Graphene possess many excellent electrical,optical,physical and chemical properties.However,they are apt to accumulate and return to the state of graphite due to van der Waals forces between the graphene sheets,resulting in the decrease of specific surface area and poor electrical conductivity,the inherent high performance of graphene are far from reflected.Gelation is an effective strategy to resolve these problems,in the recently years,graphene aerogel has widely applied in catalysis,sensors and energy device.But the present graphene aerogel tend to light and fragile characteristic and the performance is not ideal.To further improve electrical conductivity of graphene aerogel is the problem to be solved.Moreover,the functionalization of graphene aerogel would be significant due to its lack of special catalytic activity and multi-functional properties.Here,we achieve the significant improvement and functionalization of graphene aerogel in electronic conductivity,mass transfer rate and catalytic activity successfully by constructing nitrogen and sulphur functionalized multiple graphene aerogel and complexing with Ni Co2S4 nanoflakes,palladium@gold nanoalloys,and extend its application in sensors.Nitrogen and Sulphur functionalized multiple graphene aerogel was Fabricated to improve electronic conductivity and affinity to electrolyte of graphene material.The synthesis of N,S-MGA included the following processes.The first process was to use GO as raw material,thiourea and p-phenylenediamine were used as the precursors of nitrogen and sulphur-functional groups,respectively.a part of reduced graphene oxide self-assembled to produce graphene hydrogel,to obtain GO aerogel,the resulting GO hydrogel was treated by freeze-drying.The second process was to prick holes in the face of GO aerogel to breaks the most of closed pores in the GO aerogel internal,the GO aerogel was placed into another glass vial with a plug,which its inner volume consistent with volume of the GO aerogel.After that,the GO dispersion was added into the GO aerogel through the vertical holes to achieve the second graphene oxide gels.The above procedure was repeated in order to prepare a multiple GO aerogel.The third process was to activate the multiple GO aerogel by phosphoric acid.Finally reduced by the thermal annealing in Ar/H2.The studies showed that the N,S-MGA-n has an excellent three-dimensional architerature with a well-defined porous structure,the surface area up to 1106.8 m2·g-1,the specific capacitance reached to 486.8 F/g,and the N,S-MGA-n had a higher density,faster electron conductivity and improved catalytic ability compared with conventional graphene aerogel.And the electrochemical performance of N,S-MGA-n can be further improved by increasing number of the GO gelation cycle.Synthesis of Ni Co2S4/N,S-MGA and its study on electrochemical performance with a capacitor model.The synthesis of Ni Co2S4/N,S-MGA was to use TBA as a“soft templat”for the fabrication of nickel and cobalt layered double hydroxides（Ni/Co LDH）in interior of N,S-MGA,then the Na2S solution was injected into the Ni/Co-LDH/N,S-MGA to achieve the conversion of Ni/Co-LDH into Ni Co2S4.The result showed that the surface area of 76.3 m2g-1 was obtained.The specific capacitance reached to 486.8 F/g at the current of 1A/g using a three-electrode test system,while the specific capacitance remained 556.0 F/g at the current density of 6 A/g.Energy density of Ni Co2S4/N,S-MGA-5 was calculated to be 122 Wh kg-1 at the power density of 800 Wkg-1 at two-electrode system,and the specific capacitance decreases by only less than 0.62%after 3000 cycles,The above-mentioned datas indicated that the composite posses high electrochemical activity,good conductivity and excellent electrochemical stability.Reserch on the catalytic ability of Ni Co2S4/N,S-MGA toward glucose and construction of the glucose biosensor.The glucose biosensor was prepared by using Ni Co2S4/N,S-MGA-5as the sensing material and glucose oxidase as recognition element peroxide biosensor.Its differential pulse voltammetric signal linearly increases with the increase of dopamine concentration in the range from 1.0×10-51.5×10-3 M with the detection limit of 3.0×10-6M.The excellent electrochemical response attribute to the affinity to electrolyte,electronic conductivity and electrocatalytic activity of the composite.The analytical method provides good sensitivity,reproducibility,stability and reproducibility.It has been successfully applied in the detection of trace glucose in biological samples.Formation of Pd@Au/N,S-MGA and its application for detection of dopamine.The synthesis of Pd@Au nano alloy were use the prepared Pd nanocubes as a"nuclear",and combined with N,S-MGA.The composite was developed the glucose biosensor.Its differential pulse voltammetric signal linearly increases with the increase of dopamine concentration in the range from 1.0×10-9 M to 4.0×10-5 M with the detection limit of 3.6×10-10 M（S/N=3）.The ultrasensitive electrochemical response of the sensor towards dopamine ascribed to excellent electrocatalytic activity of Pd@Au and significantly electrochemical synergy between Pd,Au and N,S-MGA.The analytical method provides the advantage of sensitivity,reproducibility,rapidity and long-term stability.It has been successfully applied in the detection of trace dopamine in biological samples and recoveries in the range of 96.0%100.9%. |
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