Hierarchical N, S co-doped Fe₃O₄/C nanotubes constructed by ultrathin nanosheets for superior Li-ion batteries

In the present work, a facile strategy of synthesizing ultrathin nanosheets constructed N, S co-doped Fe₃O₄/C nanotubes via annealing the methyl orange-embedded Fe-glycerate nanotubes is reported. The nanosheet, constituting the wall of the nanotube, is formed by small Fe₃O₄ nanoparticles enchased highly graphitic carbon at a graphitization temperature as low as 450 ​°C. The nanosheets constructed N, S co-doped Fe₃O₄/C nanotubes exhibited superior electrochemical performance due to the highly accelerated intercalation/deintercalation rate of Li⁺ ions resulting from the homogeneous N and S dopants, greatly buffered volume expansion resulting from the abundant micro/meso-pores and hieratical nanosheet organized nanotube structure, and the good conductivity resulting from the graphitic carbon coating. Density functional theory (DFT) verified that N, S doping can efficiently promote the adsorption of Li⁺ ions thus accelerated the intercalation/deintercalation rate of Li⁺ ions.