Hierarchical Tubular Structures Composed of Co3O4 Hollow Nanoparticles and Carbon Nanotubes for Lithium Storage

Abstract Hierarchical tubular structures composed of Co 3 O 4 hollow nanoparticles and carbon nanotubes (CNTs) have been synthesized by an efficient multi‐step route. Starting from polymer‐cobalt acetate (Co(Ac) 2 ) composite nanofibers, uniform polymer‐Co(Ac) 2 @zeolitic imidazolate framework‐67 (ZIF‐67) core–shell nanofibers are first synthesized via partial phase transformation with 2‐methylimidazole in ethanol. After the selective dissolution of polymer‐Co(Ac) 2 cores, the resulting ZIF‐67 tubular structures can be converted into hierarchical CNTs/Co‐carbon hybrids by annealing in Ar/H 2 atmosphere. Finally, the hierarchical CNT/Co 3 O 4 microtubes are obtained by a subsequent thermal treatment in air. Impressively, the as‐prepared nanocomposite delivers a high reversible capacity of 1281 mAh g −1 at 0.1 A g −1 with exceptional rate capability and long cycle life over 200 cycles as an anode material for lithium‐ion batteries.