Sulfur and nitrogen Co-doped activated CoFe2O4@C nanotubes as an efficient material for supercapacitor applications

Developing low-cost and highly efficient electrochemical materials toward supercapacitor applications is crucial for energy conversion systems. In the present work, dual S, N-doped activated CoFe2O4@CNTs was successfully synthesized using carbamide and sodium thiosulfate as N and S precursors and CNTs as a substrate via a convenient two-step hydrothermal activation procedure, which presents good performance for supercapacitor. The characterization results indicate that activity S and N atoms can be successfully doped into the framework of CoFe2O4@CNTs with little impact on the inner morphology and structure. However, the electrode material of N2S1-CoFe2O4@CNTs exhibits a superior electrochemical performance with 1053.60 F g(-1) at 1 A g(-1) in KOH electrolyte due to synergistic effects between spinel-type metal oxides, heteroatoms and sp(2) lattice of graphitic carbon. In addition to high energy and power densities, the capacitance retention of charging-discharging reaches 93.15% at a current density of 30 A g(-1) after 5000 cycles, exhibiting an outstanding cycle stability and potential lifetime in an alkaline electrolyte. (c) 2020 Elsevier Ltd. All rights reserved.