Metal Organic Framework Derived Nanostructure (MDN) @ Reduced Graphene Oxide Composite as Bifunctional Electrocatalyst for Oxygen Reduction/evolution Reactions /

Abstract

Energy storage devices can play crucial role in reshaping energy sector by providing affordable, accessible and reliable supply of energy directly at the point of power demand and reduce load over central grid. Lithium ion batteries are deemed insufficient to meet growing energy storage needs due to their limited energy densities and capacities. Metalair batteries (especially Li-air batteries) are relatively new technologies to gain attention due to high theoretical energy densities and unique cell configurations. Li-air batteries possess remarkable theoretical energy densities roughly twenty times that of commercial Li-ion batteries (LIBs) but oxygen reduction and evolution reactions which are underpinning processes during discharge and charging cycles are severely plagued by poor electrocatalyst material. An efficient, stable and durable bifunctional electrocatalyst is needed to address its performance issues. In this study, a nanocomposite of manganese metal organic framework and graphene oxide has been synthesized by facile solvothermal method followed by thermal reduction in inert environment. Out of prepared nanocomposites, one with 75% rGO (MnBDC@75%rGO) exhibits bifunctional property and electroactivity superior to most of the recently reported catalysts. Electrochemical measurements of MnBDC@75%rGO reveal notable onset, half wave and cathodic peak potentials while achieving good current densities. It shows excellent performance for ORR and OER in terms of low overpotential, material degradation, high methanol tolerance and stable performance which can be attributed to synergistic effect from mesoporous and highly defective catalyst surface along with transition metal organic framework and rGO chemistries.