Study On The Modification And Properties Of TiO₂ Nanoelectrode Materials

With the rapid development of science and technology,the development and use of green energy storage equipments and devices with excellent performance has become a research hotspot in the field of energy and battery.Among them,supercapacitor has the characteristics of high power density and energy density,wide operating temperature range,long cycle life and low maintenance cost,which has attracted more attention.Electrode material is very important to the performance of supercapacitor.Ti O₂ nanotube arrays?Ti O₂NAs?is a kind of electrode material with good mechanical properties,large specific surface area and environment-friendly,but its electrochemical performance is poor and specific capacitance is low.At present,the main modification methods for Ti O₂NAs are:external doping,self doping,composite conductive polymer and composite carbon materials etc.In this thesis,the self-doped Ti O₂ nanotube arrays(Ti³⁺-Ti O₂NAs)was prepared by two-step anodization and annealed in Ar₂ atmosphere.Based on the modification of Ti O₂NAs by electrodeposition polyaniline?PANI?,diazonium salt?DZ?and Cerium dioxide nanoparticles?CeO₂?were introduced to prepare polyaniline/diazonium salt/titanium dioxide nanotube arrays?PANI/DZ/Ti O₂NAs?and Cerium dioxide-polyaniline/titanium dioxide nanotube arrays?CeO₂-PANI/Ti O₂NAs?,which improved the capacitance performance and cycle stability.The details of this thesis are as follows:Ti³⁺-Ti O₂NAs is prepared by two-step anodization and annealed in Ar₂ atmosphere.The properties of Ti³⁺-Ti O₂NAs are compared with that of Ti O₂NAs annealed in air.Both electrode materials have highly ordered nanotube structure,and both of them are transformed from amorphous state to anatase crystal;oxygen vacancies are generated in the Ti³⁺-Ti O₂NAs annealed in Ar₂ atmosphere,Ti⁴⁺is reduced to Ti³⁺,the charge transfer ability and electrochemical activity are enhanced,and the specific capacitance is greatly improved,from5.49 m F cm^-2to 40.86 m F cm^-2.On the basis of two-step anodization,PANI/DZ/Ti O₂NAs is prepared by electrochemical grafting diazonium salt and electropolymerizing PANI.Compared with PANI/Ti O₂NAs,PANI/DZ/Ti O₂NAs has a more regular nanostructure,the nanotubes are not blocked by PANI,the connection between PANI and Ti O₂NAs is closer,which is beneficial to the rapid transmission of electrons and avoid the collapse of nanostructures.At the current density of 12A g^-1,PANI/DZ/Ti O₂NAs can retain 83.7%of the initial specific capacitance after 2000 cycles of charging and discharging,which shows excellent cycle stability.CeO₂ prepared by homogeneous precipitation method is introduced into the electrochemical polymerization deposition process of PANI to prepare ternary nanocomposite electrode materials CeO₂-PANI/Ti O₂NAs.Compared with PANI/Ti O₂NAs,the capacitance performance and cycle stability of CeO₂-PANI/Ti O₂NAs are improved,which is attributed to the introduction of CeO₂,which is conducive to provide abundant electroactive sites,and can improve the cycle stability of PANI.In addition,the interaction among CeO₂,PANI and Ti O₂NAs is good for the stability of nanoelectrode materials.