Nanosized Co3O4-MoS2 heterostructure electrodes for improving the oxygen evolution reaction in an alkaline medium

Abstract

Nano-sized Co3O4-MoS2/Ni foam heterostructure electrodes were fabricated using a vacuum kinetic spray technique with microparticles of Co3O4 and MoS2. The deposited films were utilized to study the oxygen evolution reaction (OER) at various MoS2 contents (25, 50, 75 wt.%). The surface state of the obtained heterostructure electrodes was characterized using various surfaces sensitive techniques such as scanning electron microscopy (SEM), Raman spectroscopy, and x-ray photoelectron spectroscopy (XPS). SEM images exhibited the fragmentation of the microparticles to smaller sizes in the nanoscale range. An analysis of the XPS spectra revealed the improvement in the cumulative synergy between the nanostructured Co3O4 and MoS2 in the heterostructured Co3O4-MoS2 electrocatalyst. We found that the gradual addition of MoS2 caused an enhancement in the OER activity due to improved charge transfer kinetics. Moreover, the heterostructure electrode with 75 wt.% MoS2 showed the highest activity with the lowest OER overpotential value of 298 mV at 10 mA..cm(-2) and the smallest Tafel slope value of 46 mV.dec(-1), as well as, 50 h OER stability at a current density of 50 mA.cm(-2).