Predominantly enhanced catalytic activities of surface protected ZnO nanorods integrated stainless-steel mesh structures: A synergistic impact on oxygen evolution reaction process

Abstract The realization of efficient and durable catalyst-based energy harvesting devices by integrating low-cost materials with low-temperature techniques has recently received great attention. In this direction, we developed synergistic Oxygen evolution reaction (OER) catalysts by combining low-cost surface passivated or functionalized ZnO nanorods (F. ZnO NRs) structures with stainless-steel mesh (SSM/F. ZnO NRs) as three-dimensional (3D) structures and demonstrated excellent water-splitting characteristics. Here, SSM/ZnO nanorods structures were initially passivated by electrochemical deposition of ultrathin cobalt oxide (Co3O4) layers and analyzed with advanced analytical techniques even before and after OER catalysis. As individual materials, either stainless-steel or Co3O4 deposited ZnO nanostructures possess very low catalytic activity, whereas their integrated 3D structures showed unusual catalytic performance as OER anodes. As compared to SSM and SSM/ZnO structures, Co3O4 passivated SSM/ZnO structures exhibit very low overpotential (∼290 V for the current density of 10 mA/cm2) with a reduced Tafel slope of 59 mV/dec along with excellent cycling stability and durability even for longtime energy productions. The establishment of large surface-area and fine energy band alignments along with favorable interfaces formed between SSM, ZnO@Co3O4, and electrolyte||Pt structures, presence of Co3O4 as a passive cum protective layer, and synergistic effects play significant roles in the predominantly enhanced catalytic activity of SSM/F. ZnO electrodes.