摘要
基于金属氧化物存储机制,MoO_3比MoO_2具有更高的理论容量.本文通过热的硝酸氧化MoO_2@C纳米线成功制备出具有400.2 m2g^-1高比表面积的多孔h-MoO_3@C纳米纤维,且碳壁没有明显破坏.作为锂离子电池的负极,与MoO_2@C纳米线相比多孔h-MoO_3@C纳米纤维电极表现出更好的性能,其中在2 Ag^(-1)的电流密度下500循环后展现出302.9 mAhg^-1的可逆容量.作为钠离子电池的负极,h-MoO_3@C电极同样具有很好的倍率性能.在2 Ag^(-1)的电流密度下500循环后仍具有108.9 mAhg^-1的容量,并且在2 Ag^(-1)的电流密度下1200循环后还能保持91 mAhg^-1的容量.由于碳壁可以维持结构的完整性且可提高导电性;同时h-MoO_3的隧道结构可作为分离电子孔并为Li+/Na+嵌入脱出提供更多的特有位置,使得该复合纳米线作为电极材料表现出更好的性能.本工作为合成具有高价的过渡金属氧化物/碳复合材料在电池和催化剂领域的运用提供了依据.
Porous h-MoO_3@C nanofibers with a large specific surface area of 400.2 m^2g^（-1）were successfully synthesized with hot HNO_3 oxidizing Mo O_2@C nanofibers without obvious damage to carbon shells. As anodes for lithium ion batteries（LIBs）, the porous h-MoO_3@C nanofibers electrodes show a reversible capacity of 302.9 mAhg^（-1）at 2 A g^（-1）after500 cycles. As anodes for sodium ion batteries（SIBs）, they also can deliver a good rate capacity and hold 108.9 mAhg^（-1）at2 A g^（-1）after 500 cycles, even can have 91 mAhg^（-1）at 5 A g^（-1）after 1200 cycles. The excellent electrochemical performances of the porous h-Mo O_3@C nanofibers are attributed to the unique structure which not only can maintain the structure stability but also provide enough active sites for Li＋/Na＋. At the same time, the tunnel structure of h-Mo O_3 can lead to separate electron–hole and offer a great deal of special positions for cation（Li＋/Na＋） insertion/extraction. The present method may be helpful for the synthesis of transition metal oxides（TMOs）-carbon composites with high valence metal atoms in the field of batteries and catalysts.
基金
supported by the National Natural Science Foundation of China (51404103, 51574117 and 61376073)
Hunan University Fund for Multidisciplinary Developing (2015JCA04)
the Fundamental Research Funds for the Central Universities and the Postdoctoral Science Foundation of China (2017M610495)
