A novel edge-rich structure of CuO/Co3O4 derived from Prussian blue analogue as a high-rate and ultra-stable electrode for efficient capacitive storage

Abstract

Metal oxides derived from Prussian blue (PB) and Prussian blue analogues (PBAs) are usually used as electrode materials of supercapacitors (SCs). However, the disadvantage is few external active sites. We have successfully developed a novel yet facile strategy to prepare a novel Cu-Co mixed metal oxide (CuO/Co3O4) derived from Cu-based PBA (Cu3[Co(CN)6]2•9H2O), which can form the edge-rich structure to expose more active sites. The edge-rich structure greatly improves charge storage kinetics of electrode material, and the capacitive contribution can even reach 99% at a scan rate of 10 mV s − 1. Even at a low specific surface area, this novel electrode material possesses excellently ultra-stable and high-rate performance in 2 M KOH aqueous electrolyte (76.7% capacity retention when the current density increases from 1 to 10 A g − 1). Moreover, the hybrid supercapacitor (HSC) fabricated with the positive electrode edge-rich CuO/Co3O4 and the negative electrode nitrogen-doped graphene hydrogel (NDGH) delivers remarkable cycling stability (After 7000 cycles, 98.9% capacity is maintained). These excellent electrochemical performances can be attributed to a novel edge-rich structure, which is beneficial for exposing active sites in the external surface and thus promotes the capacitive contribution for fast redox reaction. This strategy opens up a new avenue for promoting electrochemical performance by mediating interfaces and can be extended to the fields of battery and electrocatalysis.