Lamella-heterostructured nanoporous bimetallic iron-cobalt alloy/oxyhydroxide and cerium oxynitride electrodes as stable catalysts for oxygen evolution

Abstract

Developing robust nonprecious-metal electrocatalysts with high activity towards sluggish oxygen-evolution reaction is paramount for large-scale hydrogen production via electrochemical water splitting. Here we report that self-supported laminate composite electrodes composed of alternating nanoporous bimetallic iron-cobalt alloy/oxyhydroxide and cerium oxynitride (FeCo/CeO_2−xN_x) heterolamellas hold great promise as highly efficient electrocatalysts for alkaline oxygen-evolution reaction. By virtue of three-dimensional nanoporous architecture to offer abundant and accessible electroactive CoFeOOH/CeO_2−xN_x heterostructure interfaces through facilitating electron transfer and mass transport, nanoporous FeCo/CeO_2−xN_x composite electrodes exhibit superior oxygen-evolution electrocatalysis in 1 M KOH, with ultralow Tafel slope of ~33 mV dec⁻¹. At overpotential of as low as 360 mV, they reach >3900 mA cm⁻² and retain exceptional stability at ~1900 mA cm⁻² for >1000 h, outperforming commercial RuO₂ and some representative oxygen-evolution-reaction catalysts recently reported. These electrochemical properties make them attractive candidates as oxygen-evolution-reaction electrocatalysts in electrolysis of water for large-scale hydrogen generation.

Developing stable catalysts for industrial-scale current densities is challenging. Here, the authors report self-supported laminate electrodes composed of nanoporous bimetallic iron-cobalt alloy/oxyhydroxide and cerium oxynitride hybrid that can catalyze the oxygen evolution reaction at high current densities.