Transition metal (Ni, Cu and Fe) doped MnS nanostructures: Effect of doping on supercapacitance and water splitting

Increasing demand for sustainable energy has boosted the exploration of inexpensive and efficient catalysts. Transition metal sulfides have been proven as efficient electrocatalysts for energy storage or energy generation applications. Herein, cubic phase α-MnS and transition metal (Cu2+, Fe3+, and Ni2+) doped MnS nanoparticles were synthesized via the hot injection method from their piperazinyl dithiocarbamate complexes, respectively. The morphology of pristine and TM-doped MnS nanoparticles was studied using transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analysis, while optical and structural properties were studied using UV–visible spectroscopy and powder X-ray diffraction (p-XRD), respectively. p-XRD analysis confirmed the successful incorporation of dopants into MnS lattice structure and suitability of heterocyclic dithiocarbamate complexes for phase/composition controlled synthesis of nanomaterials. The effect of doping on electrocatalytic properties was also investigated. The MnS-based electrodes doped with Ni and Fe presented satisfactory specific capacitances of 840 and 900 F/g at 2 mV/s scan rate. In addition, the testing for electrocatalysis for the water-splitting process demonstrated that Ni–MnS had a superior performance for HER with a η of 132 mV at 10 mA/cm2 and Tafel slope of 44 mV/dec. On the other hand, Fe–MnS showed better performance towards OER with a η of 280 mV at 10 mA/cm2 and a Tafel slope of 60 mV/dec.