Green Synthesis and Electrochemical Study of Cobalt/Graphene Quantum Dots for Efficient Water Splitting

Abstract

Hydrogen production via electrochemical water splitting is limited thermodynamically by the sluggish oxygen evolution reaction (OER) at the anode. The use of noble metal-based catalysts leads to an economic bottleneck because of the high cost associated with such materials. This article is an electrochemical investigation of an economically viable and advanced OER catalyst made of cobalt/graphene nanocomposite quantum dots (QDs). A series of characterization techniques, such as high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and fluorescence measurements, were performed, and they confirmed the formation of graphene QDs as well as the formation of cobalt-based QDs. A very high current density of 43.16 mA cm–2 was observed for the QD nanocomposite, whereas smaller current densities were seen for Co nanoparticles (21.1 mA cm–2) and a benchmark Pt/C commercial catalyst (5.99 mA cm–2). Furthermore, an overpotent...