Supercapacitor and OER activity of transition metal (Mo, Co, Cu) sulphides

Multifunctional transition metal (Mo, Co, Cu) sulphide electrocatalysts were synthesized employing hydrothermal method with stabilization at 180 °C for 24 h for both supercapacitors and water splitting applications. Rhombohedral (MoS2) and hexagonal (CoS and CuS) structures of the electrocatalysts were identified from the X-ray diffraction patterns. Raman-active modes confirmed the characteristic phonon vibrations. The prepared sulphides optical studies were examined employing photoluminescence spectroscopy and UV spectroscopy. Morphological variations observed for different sulphide nanostructures were confirmed by the scanning electron microscopy images. A comparative electrochemical study of MoS2, CoS and CuS was performed. Of the three candidates, MoS2 has superior capacitive behaviour, exhibiting very high specific capacitance of 513F/g at 0.5 A/g, and moreover exhibited the highest oxygen evolution reaction current density of 442.7 mA/g at a scan rate of 10 mV/s. Furthermore, it maintained its performance for longer in 1000 cycles of galvanostatic charging and discharging and in 12 h of an oxygen evolution reaction stability test.