| Polyaniline has attracted extensive attention due to its easily available synthesis,unique doping/dedoping mechanism and so on.Therefore,it has beenwidely recognized as a very promising prospect,especially in the application of the two electrochemical systems of supercapacitors and electrochemical sensing.However,there are some disadvantages for polyaniline,such as poor mechanical stability,limited conductivity and so on,which limits its application in these two electrochemical systems.It is well known that the electrode materials and structures are key to the improvements of the two electrochemical systems.Therefore,according to the characteristics and requirements of different electrochemical systems,it is very important to prepare the binary or multiple nanocomposites by compounding inorganic functional nanomaterials and polyaniline with different structure design.The synergistic effect will enhance electrode materials.This paper made an innovative study on the electrode materials of supercapacitors and electrochemical sensors based on the compounds of polyaniline with functional nanomaterialsusing different methods.? In the filed of supercapacitor,the paper mainly focused on the preparation of electrode materials,which effectively enhanced the electrochemical performance based on polyiline.Considering to combine the advantages of polyaniline,one-dimensional multiwalled carbon nanotubes and two-dimensional layered materials(molybdenum disulfide and graphene),it started from the structural design.On the other hand,we alsosystematically explored the effects of functional components and preparation methods on the structure and properties of the nanocomposites,and also investigated the mechanism of the controlled structure and improved performance.Meanwhile,the ternary nanocomposites were assembled into symmetrical supercapacitor devices to characterize the practical application.?In order to make full use of the advantages of polyaniline and further broaden the application of polyaniline in the fields of electrochemical sensors,a nonenzymatic sensor was constructured with excellent electrocatalytic activity for glucose by introduction of Ag-Pt bimetallic nanoparticles.Due to the high conductivity and comparatively more surface avtive sites of polyaniline,it can be used as load material to construct the biosensor.The catalytic mechanism of the sensor was explored.This paper mainly focused on the following four aspects:1.Multiwalled carbon nanotubes/polyaniline(MWCNTs/PANI)binary nanocomposites were synthesized with core-shell structure by chemical in situ polymerization,in which the aniline monomers were polymerized on the surface of MWCNTs.The microstructure,composition and electrochemical performance of the binary nanocomposites were characterized by a series of methods.In the composites,the introduction of MWCNTs not only played a role in framework support and conductive network,but also provided the electrical double layer capacitance,which improved the electrochemical performance of PANI.Moreover,the thickness of PANI coating layer on the surface of MWCNTs could be controlled by changing the mass ratio of aniline monomers and MWCNTs.The influence mechanismof the thickness of PANI coating layer on the electrochemical capacitive performance of materials was investigated.When the amount of aniline monomers was 0.3 g[m(anilne):m(MWCNTs)=4.29],the MWCNTs/PANI nanocomposites(MP-3)possessed high specific capacitance of 474.9 F g-1(0.5 A g-1).Furthermore,67.82%of the initial specific capacitance was retained after 1000 charging/discharging cycles and the capacitance of pure PANI retention rate was 48.97%.The results indicated that the addition of MWCNTs could improve the capacitance and cycling stability of PANI.2.In order to better improve the electrochemical capacitance and cycling stability of MWCNTs/PANI nanocomposites,outside the PANI coating layer,layer-structured molybdenum disulfide(MoS2)nanomaterials was introduced for synthesizing ternary nanocomposites with a multi-level structure.This new compounds could be applied to the supercapacitor electrode material.Then,the synergistic effect of each component on the electrochemical properties of nanocomposites was studied.MoS2 with different morphologies grown on the surface of MWCNTs/PANI were obtained by changing the amount of the precursor(ammonium molybdate and thiourea,m(amnounium molybdate):m(thiourea)=1.16).When the amount of ammonium molybdate was 0.1 g[m(amnounium molybdate):m(WCNTs/PANI)=3.33],the nanoflower-like MoS2 was grown on the surface of MWCNTs/PANI nanostem.The specific capacitance of the composites was 542.56 F g-1(0.5 A g-1),and 74.25%of the initial specific capacitance was retained after 2000 charging/discharging cycles.The dominant factor was that the structure of nanoflower-like MoS2 layer was relatively loose.The structure contributed to the contaction between MoS2 and electrolyte and provided large double-layer capacitance.Meanwhile,this kind of nanostructure did not obstruct the transmission of proton and electron between PANI and H2SO4 electrolyte,which could maintain the faradaic pseudocapacitance property of PANI.Furthermore,the MoS2 covered properly on the surface of MWCNTs/PANI could suppress the volume change of PANI from the outside,resulting in a better cycling stability.Lastly,the MPM-0.1 nanocomposites were assembled into symmetrical supercapacitor devices.The electrochemical tests showed that the specific capacitance of the device was 257.23 F g-1 at the current density of 0.5 A g-1,and 65.12%of specific capacitance was retained after 2000 cycles.3.This chapter introduced graphene nanosheets with more excellent conductivity,larger specific surface area and outstanding mechanical properties.The MWCNTs/PANI/PSS-GR ternary nanocomposites with sandwich-like structure were prepared for supercapacitor electrode materials by the electrostatic adsorption between the negatively-charged PSS-GR and positively-charged MWCNTs/PANI.The influence of the synergistic effect of graphene,MWCNs and PANI on the electrochemical performance of the electrode materials was been studied.The influence mechanism of the sandwich-like structure and amount of graphene on the electrochemical capacitance performance and stability was also investigated.The results showed that when the amount of graphene nanosheets was added 20 mg[m(graphene):m(MWCNTs/PANI)=0.4],the specific capacitance of the MPG20 was the largest.The value of capacitance was 602.5 F g-1 at the current density of 0.5 A g-1.78.32%of the initial specific capacitance was retained after 2000 cycles,which revealed the electrode materials had excellent cycling stability.Owing to the high conductivity and large specific surface area of graphene,this kind of sandwich-like structure could effectively prevent the agglomeration of graphene nanosheets and improve the double layer capacitance value.Moreover,graphene nanosheets could suppress the volumetric swelling and shrinking of PANI during the charging/discharging process frorm the outside.This performance was useful for enhancing the cycling stability.Finally,the MPG20 nanocomposites were assembled into symmetrical supercapacitor devices.The tests of the two electrode system displayed that the specific capacitance of the device was 332.5 F g-1 at the current density of 0*5 A g-1,and 69.58%of specific capacitance was retained after 2000 cycles.The excellent performance of the nanocomposites made it a promising material in the field of supercapacitors.4.MWCNTs/PANI/Ag-Pt quaternary nanocomposites were prepared by depositing Ag-Pt bimetallic nanoparticles uniformly onto the surface of MWCNTs/PANI nanofibers via the chemical co-reduction of AgNO3 and H2PtCl6.H2O.It was applied to design the simple nonenzymatic sensor.The electrochemical sensing properties of the sensor and its electrocatalytic activity for glucose oxidation were analysed.A new method for the detection of glucose was established.The tests results of the new biosensor showed that the obtained liner range was 12 ?M?10.5 mM(RZ=0.996),the sensitivity was 11.4 ?A mM-1 and the detection limit was as low as 7.6 ?M(S/N=3).The performance showed that the addition of Ag nanoparticles could decrease the amount of Pt and enhanced the electrocatalytic activity of Pt effectively. |
PDF Full Text Request