| Energy and environmental problems become two important issues with the development of human society.Titanium Dioxide(TiO2)is widely used in various industries due to its inherent advantages of low cost,good stability,low self-discharge point,high light absor:ption activity,high light corrosion resistance and environmental friendly.The applications of TiO2 nanomaterials in lithium ion battery(LIB)and photocatalysis have been widely studied for energy storage and water pollution degardation,respectively.Nevertheless,TiO2 also has some drawbacks which limit its applications.As an anode material,the low specific capacity and poor conductivity of TiO2 greatly hinders its application in LIBs.On the other hand,despite the TiO2 exhibits high photocatalytic activity in the field of photocatalysis,the inherent drawbacks of large band gap,low utilization of visible-light and high recombination rate of photogenerated electron-holes still limit its practical application.In order to solve these problems,a series of modifications were conducted to improve the performances of TiO2 in LIBs and photocatalysis.Herein,a facile,economical and environmental friendly freezing-template method was utilized to to synthesize CNTs/TiO2 nanosheets.The coupling of CNTs can significantly improve the conductivity and structural stability of TiO2 nanosheets in addition enhance the absorption of visible-light.Moreover,the unique 2D porous structure can lead to large specific surface area and more active sites.The improvemnt of electrochemical performance for different diameter of CNTs synthesize CNTs/TiO2 nanosheets were subsequently investigated in this work.The 8 nm CNTs/TiO2 nanosheets show the best performence in LIBs,which exhibit high specific capacity of 260.2 mAh·g-1 at current density of 100 mA·g-1.After 100 cycles at current density of 100 mA·g-1,the specific capacity slightly reach to 210.0 mAh·g-1,increase 43.1%compared to TiO2 nanosheets.While at current density of 1000mA·g-1,the reversible specific capacity of 8 nm CNTs/TiO2 nanosheets remains 121.8 mAh·g-1 after 1000 cycles,which is around 0.0064%decrease per cycle of the original capacity.Moreover,the Coulomb efficiency maintains approximately 100%in the whole process.Furthermore,different amount of CNTs doping in CNTs/TiO2 nanosheets also be researched in photocatalytic degradation of methylene blue(MB).The increased coupling of CNTs limits the growth of TiO2 grain and simultaneously hinders the recombination of photogenerated electron-hole pairs,meanwhile enhances the absorption of visible light.Whereas the excess CNTs may limits the photoelectric effect of CNTs/TiO2 nanosheets.Under visible light illumination,when the mass ratio of CNTs reach 20 wt.%,the CNTs/TiO2 nanosheets exhibit the best photocatalytic activity,72.1%of methylene blue(MB)is photo-degraded after 3 h,which is 26%higher than that of the TiO2 nanosheets.Beside that,amorphous TiO2(a-TiO2)nanosheets are fabricated by freezing-template method and subsequently calcined at low temperature(250 0C),and then the a-TiO2 is used as anode material in LIBs.The specific discharge capacity of a-TiO2 nanosheets in the first cycle can reach 736.9 mAh·g-1 at a current density of 100 mA g-1 and remains 404.8 mAh·g-1 after 100 cycles,which is much higher than that of crystalline TiO2(c-TiO2).At high current density of 1000 mA g-1,the reversible specific capacity maintains 256.2 mAh g-1 after 1000 cycles,only slight decrease of the specific capacity is observed which imply that the a-TiO2 is stable even at high current density.The results show that a-TiO2 nanosheets exhibit significantly enhancement of electrochemical performance. |
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