Fabrication of MnCoS Thin Films Deposited by the SILAR Method with the Assistance of Surfactants and Supercapacitor Properties

Compact MnCoS thin films on a nickel foam (NF) substrate were prepared by successive ionic layer adsorption and a reaction (SILAR) method, and two surfactants (SDS and CTAB) were used to improve the wettability of the NF. The MnCoS thin films were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The supercapacitive properties were evaluated by cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and impedance spectroscopy (EIS). The results show that while the NF was first dipped in surfactant solution, followed by a mixture of Mn2+ and Co2+ or a Na2S solution, the load and density of the MnCoS on the NF’s surface significantly increased and delivered a much higher specific capacitance than that of the MnCoS thin film formed without the assistance of surfactants, which were 2029.8 F g−1 (MnCoS-CTAB), 1500.3 F g−1 (MnCoS-SDS), and 950.4 F g−1 (MnCoS-H2O) at a current density of 1 A g−1 in 3 M KOH aqueous solution. When the current density increased to 10 A g−1, the MnCoS-CTAB with the highest specific capacitance exhibited a capacitance of 1371.9 F g−1, with a 71% capacity retention up to 1000 cycles, showing a good rate performance and cycle stability.