Engineering coordination polymer-derived one-dimensional porous S-doped Co3O4 nanorods with rich oxygen vacancies as high-performance electrode materials for hybrid supercapacitors

Abstract

Structure and defect manipulation are regarded as efficacious strategies to boost the electrochemical activity of electrode materials. Herein, the construction of one-dimensional (1D) porous S-doped Co₃O₄ nanorods with rich oxygen vacancies is demonstrated through a facile metal–organic framework-engaged strategy. Starting from a Co-NTA (NTA = nitrilotriacetic acid) precursor, the S-doped Co₃O₄ nanorods were obtained after calcination and sulfurization. As a faradaic electrode material, the S-doped Co₃O₄ nanorods exhibited enhanced specific capacitance (319.3 C g⁻¹ at 0.5 A g⁻¹) in comparison with the Co₃O₄ intermediate product (98.3 C g⁻¹) and the Co-NTA precursor (40.2 C g⁻¹). Besides, it showed an ultra-high rate capability of 83.3% with a 20-fold increase in current density (10 A g⁻¹). The hybrid supercapacitor comprising the S-doped Co₃O₄ (cathode) and the activated carbon (anode) showed a high energy density of 38.1 W h kg⁻¹ at a power density of 800 W kg⁻¹, and 31.1 W h kg⁻¹ was maintained at 8000 W kg⁻¹. It also has excellent electrochemical stability, and 87.57% of its initial capacitance was maintained after 5000 cycles, demonstrating great prospects in electrochemical energy storage applications. The excellent energy storage property of the S-doped Co₃O₄ is due to its unique 1D S-doped Co₃O₄ porous nanorod structure, i.e., large surface area, easy diffusion of ions, good conductivity, and rich redox reactions. This work may pave the way for the fabrication of desirable electrode materials through vacancy defects and nano-/microstructure engineering.