Monitoring the synergistic effect of Mn/Ni Co-doping and morphological engineering in α-Fe2O3 for energy storage capacity as battery type electrode material

Abstract

Morphology engineering and elemental doping proved to be an efficient way to enhance the capacitive performance of electroactive materials. To investigate the tuning of morphology via doping here, pure α-Fe2O3 and Ni1-xMnxFeO3+δ (x = 0,0.3,0.5,0.7,1) was synthesized via the hydrothermal method and investigated the impact of Ni and Mn doping on the structural, morphological, and electrochemical properties of α-Fe2O3. The XRD and Raman spectra confirmed the single-phase hematite's rhombohedral crystal structure of pure α-Fe2O3 with no extra peaks confirming the Ni and Mn doping without impurities. SEM analysis demonstrated a shift in the morphology of nanostructures, from spherical to nano-rod structures with increasing the concentration of Mn doping. Cyclic voltammetry results unveiled the battery-type behavior of Ni1-xMnxFeO3+δ nanoparticles while GCD results indicated an escalation in specific capacity from 380 Cg-1 (706 Fg-1) to 751 Cg-1 (1251 Fg-1) with higher Mn content. This increase culminated in the highest specific capacity of 751 Cg-1 (1251 Fg-1) for α-MnFeO3 +δ nanoparticles at the current density of 1 Ag-1 which is higher than α-Fe2O3 (380 Cg-1), NiFeO3+δ (425 Cg-1), Ni0.7Mn0.3FeO3+δ (470 Cg-1), Ni0.5Mn0.5FeO3+δ (530 Cg-1), and Ni0.3Mn0.7FeO3+δ (590 Cg-1). In addition, α-MnFeO3+δ exhibited a remarkable charge capacity retention (96%), and 100% coulomb efficiency after 10,000 consecutive GCD cycles. The noteworthy specific capacity and robust stability of the α-MnFeO3+δ nanorods suggest their suitability as potential candidates for battery type supercapacitors.