rGO supported cobalt-manganese based nanocomposite with improved electrochemical water oxidation catalysis

Design and development of low-cost element based electrocatalyst for oxygen evolution reaction is highly desirable. The present work reports first-row transition series metal ion based bimetallic CoMnOx catalyst anchored on reduced graphene oxide via one step reflux method as an efficient water oxidation catalyst. CoMnOx@rGO shows an overpotential of 290 mv to achieve a current density of 10 mA cm−2 which is 1.4 times less than CoMnOx only. Moreover, the catalyst maintains long term stability for almost 24 h in an alkaline medium. In the presence of rGO, the catalyst exhibits the mass activity of 0.39 A mg−1 which was nearly 2.6 times higher than bare CoMnOx. Further, the Tafel slope value obtained for composite CoMnOx@rGO and CoMnOx was found to be 67 and 145 mV/dec respectively. The superior electrocatalytic performance of the rGO supported catalyst is attributed to the synergy between the metal oxide and the carbon layers. rGO not only prevents the agglomeration of the metal oxide thereby maintaining the availability of the active sites but also enhances the electroconductivity of the developed electrocatalyst. The superior performance of the CoMnOx@rGO composite which also exhibits excellent stability will provide new insights towards the design of the electrocatalyst for OER reaction.