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

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 degrees C, 350 degrees C, 450 degrees C and 650 degrees C). The surface morphology of the films revealed the presence of a nanosheet percolation network that was converted into nanoplatelets after annealing at 650 degrees C. The nanosheets are composed of nanocrystals and the crystal size of the MnCo2O4 spinel oxide increased from 10 nm after 250 degrees C annealing to 100 nm after 650 degrees 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 degrees C and 650 degrees C, respectively. The spinel films displayed specific capacitance values above 400 Fg(-1) at 1 Ag-1, making these spinel oxides promising pseudocapacitive materials.