Fe-Co-S nanoarrays on nickel foam as binder-free electrodes for energy storage and electrocatalysis

The peapod-like Fe-Co-S structure, composed of tightly integrated 2D nanosheets and 0D nanospheres embedded within, adeptly integrates the advantages of both dimensional architectures and exhibits exceptional electrochemical properties. For the HSC device, it displays a high energy density of 65.9 W h kg−1 at a power density of 802.7 W kg−1. For OER, it exhibits a low overpotential of 210 mV at 10 mA cm−2 and a low Tafel slope of 55.67 mV dec−1. [Display omitted] •A self-supported peapod-like Fe-Co-S nanoarrays was designed and fabricated.•It integrated the advantages of both nanosheets and nanospheres.•Such structure facilitated ion transport and offered an expanded surface area.•The binder-free Fe-Co-S excelled in both supercapacitors and oxygen evolution reaction. The development of low-cost, high-efficiency and stable electrocatalysts for oxygen evolution reaction (OER) and supercapacitor electrode materials is of great significance for energy conversion and storage systems. However, fabricating multifunctional electrode materials that demonstrate both excellent energy storage properties and outstanding catalytic performance remains a challenge. Herein, a self-supported Fe-Co-S electrode with a distinctive peapod-like structure was designed and fabricated via a simple hydrothermal method. This peapod-like structure, composed of tightly integrated 2D nanosheets and 0D nanospheres embedded within, could facilitate ion transport and offer an expanded surface area for more exposed active sites. Therefore, the prepared Fe-Co-S displayed an exceptionally high specific capacity (1158 C g−1 at 1 A g−1), outstanding rate capability (750 C g−1 at 30 A g−1), remarkable stability in the three-electrode configuration, as well as a high energy density of 65.9 W h kg−1 at a power density of 802.7 W kg−1 for the hybrid supercapacitors (HSCs). In addition, when used as an electrocatalyst for OER, it exhibited excellent catalytic performance with a low overpotential of 210 mV at 10 mA cm−2 and a low Tafel slope of 55.67 mV dec-1. Hence, it holds significant potential for applications in supercapacitors and electrocatalysis.