Structural evolution, magnetic properties and electrochemical response of MnCo2O4 nanosheet films

Abstract

MnCo₂O₄ spinel oxide nanosheets were prepared via electrodeposition and post thermal annealing on stainless steel substrates. The structural transformation of an electrodeposited hydroxide phase into a spinel phase was achieved by thermal annealing at different temperatures (250 °C, 350 °C, 450 °C and 650 °C). The surface morphology of the films revealed the presence of a nanosheet percolation network that was converted into nanoplatelets after annealing at 650 °C. The nanosheets are composed of nanocrystals and the crystal size of the MnCo₂O₄ spinel oxide increased from 10 nm after 250 °C annealing to 100 nm after 650 °C annealing, in which a twinning was observed. The magnetic transition temperature also increased from 101 K to 176 K for the films annealed at 250 °C and 650 °C, respectively. The spinel films displayed specific capacitance values above 400 Fg⁻¹ at 1 Ag⁻¹, making these spinel oxides promising pseudocapacitive materials.