Observation of morphology resembling Hydrangea macrophylla flower in SILAR-deposited MFeO (M=Co, Ni, Mn) nanocrystallites: synergetic effect on electrochemical performance.

The successive ionic layer adsorption and reaction (SILAR) experimental process has been used to develop a high-efficiency electrode of MFeO (M = Ni, Co and Mn) on substrates at ambient temperature. Structural, morphological and electrochemical properties have been investigated using x-ray diffraction (XRD), a scanning electron microscope (SEM) and an electrochemical test station, respectively. A morphology resembling the Hydrangea macrophylla flower has been observed and tuned with varying Fe concentration. The formation of MFeO demonstrates the efficient electrochemical behavior and the specific capacitance has been evaluated as ∼1380, ∼972 and ∼815 Fg for CoFeO (CF), NiFeO (NF) and MnFeO (MF), respectively, at a current density of 1 Ag. Also, the developed electrodes maintain excellent cyclic retention of ∼92%, ∼89% and ∼86% for CF, NF, and MF, respectively, up to 5000 cycles. Further, asymmetric solid-state supercapacitor (ASC) devices have been fabricated using the best compositions of MFeO as a positive electrode and carbon black (CB) as a negative electrode, and successfully illuminate a 1.8 V commercial LED.