Fabrication of nickel foam supported Cu-doped Co3O4 nanostructures for electrochemical energy storage applications

In this study, we have synthesized hierarchical nano-discs of Cu doped Co3O4 (Cu·Co3O4) and decorated them directly on the 3D nickel foam (NF) via single-step urea assisted hydrothermal method. The crystal structure and elemental composition of the fabricated sample were examined using PXRD, Raman, and EDX analyses. The morphology, particle size, and structure of the fabricated sample were evaluated by FESEM analysis. I–V experiments showed that the Cu·Co3O4 samples exhibited higher conductivity (8.73 × 10−3 Sm−1) than the un-doped sample (6.42 × 10−5 Sm−1). The electrochemical investigation revealed that Cu·Co3O4@NF electrode displayed a higher specific capacitance of 728 F/g @1 A/g and exceptional cyclic activity, as after 6000 electrochemical cyclic tests it retains 98.3% of its initial specific capacitance. In comparison, the undoped Co3O4@NF electrode showed inferior electrochemical aptitude as it exhibited 566 F/g specific capacitance @1 A/g and holds just 60.2% of its initial capacitance after 6000 electrochemical tests. Additionally, on increasing the applied current density from 1 A/g to 7 A/g the Cu·Co3O4@NF electrode showed a lower capacity fade of 16%, indicating its excellent rate capability. The integrated electrochemical features (good rate capability, specific capacitance, and superior cyclic activity) of the Cu·Co3O4@NF sample were attributed to its superb electrical conductivity (8.73 × 10−3 Sm−1), binder-free design, 2D morphology, porous nature, and hierarchical structure. The synergistic effects among the acquired novel features of the doped sample not only enhanced its exposed surface area, but also buffered the Cu·Co3O4 samples from pulverization, volume expansion, and agglomeration during the electrochemical investigations.