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

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.