Ultrathin Fe(OH)3 nanosheets coated NiCo2O4 nanotube arrays as a polymetallic catalyst for oxygen reduction reaction and zinc-air battery

Developing highly efficient, low-cost and superior stable electrocatalysts for the oxygen evolution reaction (OER) is essential for coping with global energy shortage and environmental crisis. In this article, a polymetallic catalyst of ultrathin Fe(OH)3 nanosheets uniformly embedded in NiCo2O4 porous nanotube arrays (Fe(OH)3-NiCo2O4/ NF) was synthesized via a simple hydrothermal-annealing and electrodeposition method. Benefits from the synergistic effect and their unique interactions between Fe(OH)3 and NiCo2O4, the Fe(OH)3-NiCo2O4/NF triggers optimum electronic properties, rich multiple active sites, and favorite free adsorption energy, resulting in excellent OER catalytic activities. Meanwhile, the highly porous of Fe(OH)3 and NiCo2O4 effectively promotes a multichannel architecture for charge transfer and gas/ion diffusion to improve stability. Such core-shell Fe(OH)3NiCo2O4/NF hybrid was used as a polymetallic catalyst, exhibiting a small overpotential of 268 mV at a current density of 50 mA cm-2 and low Tafel slope of 73.1 mV dec ? 1 for OER in 1 M KOH. In the battery system with Fe (OH)3-NiCo2O4/NF as the cathode and zinc sheet as the anode, the zinc-air battery (ZAB) exhibits an open-circuit voltage of 1.32 V and an instantaneous current of 0.96 A. This material provides a new idea for the coupling of amorphous materials and transition metal compound, and the application of ZAB.