TiO2 nanofibers（TiO2/NFs） have been synthesized through an electrospinning method and annealed at 400, 500 and 600 ℃ to optimize their systems. The effects of annealing temperature on the electrochemical properties...TiO2 nanofibers（TiO2/NFs） have been synthesized through an electrospinning method and annealed at 400, 500 and 600 ℃ to optimize their systems. The effects of annealing temperature on the electrochemical properties for lithium ion batteries（LIBs） are assessed. The obtained LIB properties for TiO2 nanofiber anodes annealed at 400 ℃（denoted as TiO2/NFs-400） are much better than those of TiO2/NFs-500 and TiO2/NFs-600. The TiO2/NFs-400 anodes show good LIB performance with capacities of 180 and 150 m Ah/g tested at 200 and 600 m A/g after 100 cycles with almost no capacity loss and superb rate performance. The XRD results show that the pure anatase phase TiO2 can form at 400 ℃ for TiO2/NFs-400, while mixed phases of anatase and rutile are emerged at TiO2/NFs-500 and TiO2/NFs-600. Furthermore, the TiO2 nanoparticles are combined in nanofibers, and their corresponding crystal particle size for TiO2/NFs-400 was smaller than that of the other two samples. It is concluded that the superior electrochemical performance of the TiO2/NFs-400 anodes could be due to their pure crystal of anatase, small nanoparticles and non-ideal crystal lattices.展开更多
Crystal structures, electronic structures and optical properties of nitrogen and ytterbium doping anatase TiO2 were calculated by first principles with the plane-wave ultrasoft psendopotential method based on the dens...Crystal structures, electronic structures and optical properties of nitrogen and ytterbium doping anatase TiO2 were calculated by first principles with the plane-wave ultrasoft psendopotential method based on the density functional theory. The calculated results show that the octahedral dipole moments in TiO2 increase due to the changes in lattice parameters, bond length and charges on atoms, which is very effective for the separation ofphotoexcited electron-hole pairs and the improvement of the photocatalytic activity ofTiO2. The interband transition between OPπ states and Yb4f states make nitrogen and ytterbium doped TiO2 manifest greater absorption coefficients in the visible-light region.展开更多
基金supported by the NSFC(21473096,21603112)the Special Project for Fujian Provincial Universities(JK2014055)+1 种基金the Research Project of Science and Technology of Ningde City(20140218,20150169)the Fund Projects of Scientific Research Innovation of Ningde Normal University(2013T03)
文摘TiO2 nanofibers（TiO2/NFs） have been synthesized through an electrospinning method and annealed at 400, 500 and 600 ℃ to optimize their systems. The effects of annealing temperature on the electrochemical properties for lithium ion batteries（LIBs） are assessed. The obtained LIB properties for TiO2 nanofiber anodes annealed at 400 ℃（denoted as TiO2/NFs-400） are much better than those of TiO2/NFs-500 and TiO2/NFs-600. The TiO2/NFs-400 anodes show good LIB performance with capacities of 180 and 150 m Ah/g tested at 200 and 600 m A/g after 100 cycles with almost no capacity loss and superb rate performance. The XRD results show that the pure anatase phase TiO2 can form at 400 ℃ for TiO2/NFs-400, while mixed phases of anatase and rutile are emerged at TiO2/NFs-500 and TiO2/NFs-600. Furthermore, the TiO2 nanoparticles are combined in nanofibers, and their corresponding crystal particle size for TiO2/NFs-400 was smaller than that of the other two samples. It is concluded that the superior electrochemical performance of the TiO2/NFs-400 anodes could be due to their pure crystal of anatase, small nanoparticles and non-ideal crystal lattices.
基金supported by the National Natural Science Foundation of China(No.50862009)the New Century Excellent Talents in University of Ministry of Education,China(No.NCET-04-0915).
文摘Crystal structures, electronic structures and optical properties of nitrogen and ytterbium doping anatase TiO2 were calculated by first principles with the plane-wave ultrasoft psendopotential method based on the density functional theory. The calculated results show that the octahedral dipole moments in TiO2 increase due to the changes in lattice parameters, bond length and charges on atoms, which is very effective for the separation ofphotoexcited electron-hole pairs and the improvement of the photocatalytic activity ofTiO2. The interband transition between OPπ states and Yb4f states make nitrogen and ytterbium doped TiO2 manifest greater absorption coefficients in the visible-light region.
