Electrochemical performances of MnO2/Fe3O4/activated carbon ternary composites for supercapacitor and direct ethanol fuel cell catalyst application

Abstract

MnO2 and Fe3O4 nanoparticles' slow ion-diffusion kinetics and weak electrical conductivity hinder their electrochemical performance in supercapacitors and their energy-conversion ability in direct ethanol fuel cells (DAFCs). Combining MnO2/Fe3O4 with biomass-based activated carbon (AC), which is conductive, inexpensive, and has a long cycle life, to create MnO2/Fe3O4/AC can improve their electrochemical performances for ethanol oxidation and in supercapacitors. Herein, MnO2/Fe3O4/AC ternary composites were synthesized via a facile method. The physicochemical and electrochemical properties of pure and composite materials were characterized using TGA-DTA, XRD, FTIR, BET, SEM-EDX, TEM, HRTEM, SAED, CV, and EIS. The composite MnO2/Fe3O4@8%AC exhibited the highest specific capacitance, with a value of 515.113 F g−1 at 1 A g−1. Furthermore, in cyclability tests, after 700 cycles at a current density of 1 A g−1, its charge-storage performance showed an 81.83% capacity retention and a maximum energy density of 27.679 W h kg−1. Upon integration in a DAFC, MnO2/Fe3O4@8%AC electrocatalytic ethanol oxidation was achieved with a maximum power density of 44.41 mW cm−2, indicating better performance than that of other pure and composite catalysts. Therefore, this work provides a potential candidate for use in efficient energy-storage devices and an effective catalyst electrode for the ethanol oxidation reaction.