Enhanced Electrochemical Performance of CTAB-Assisted Zn-Doped Perovskite NiMnO3 Nanocrystals on Reduced Graphene Oxide for Supercapacitor and Oxygen Evolution Reactions

Abstract

This paper introduces a novel chemical reduction synthesis method for preparing bimetallic Zn-doped perovskite NiMnO3 ultrafine nanocrystals, which are further supported on reduced graphene oxide (rGO). These nanocrystals are synthesized with the assistance of cetyltrimethylammonium bromide (CTAB), and their application as positive electrode materials in asymmetric supercapacitors and oxygen evolution reaction (OER) activity is explored. Our investigation reveals that the addition of CTAB and Zn significantly enhances the specific capacitance of the Zn-doped NiMnO3, particularly when supported on rGO-nanoribbon. The synthesized CTAB-assisted Zn-doped NiMnO3 on rGO-nanoribbon (CT@Zn/NMO-rGO) exhibits an impressive specific capacitance of 1404 F/g (specific capacity of 982.5 C/g) at a 0.1 A/g in 2 M KOH solution. Especially, CT@Zn/NMO-rGO electrode maintains capacity retention of 89.2% after 30,000 cycles. Furthermore, we have successfully constructed a solid-state asymmetric coin cell using the CT@Zn/NMO-rGO as the anode and rGO as the cathode, with 2 M KOH electrolyte. This supercapacitor demonstrates a specific capacitance of 178.4 F/g (specific capacity of 303.3 C/g) at a 0.1 A/g. It also achieves an energy density of 121.8 W h/kg at a power density of 8.03 k W/kg. Notably, it maintains a robust capacity retention of 83.3% after 10,000 GCD cycles. Moreover, this CT@Zn/NMO-rGO electrode demonstrates extremely low overpotential of 296 mV for the OER, along with a low Tafel slope of 144.4 mV/dec at 10 mA/cm² in an alkaline medium. It maintains excellent stability for a duration of at least 7 days at high current density of 100 to 300 mA/cm², with minimal deviation. These findings indicate a promising potential for the use of CT@Zn/NMO-rGO in hybrid wearable energy storage devices and OER activity.