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/CeO2−xNx) 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/CeO2−xNx heterostructure interfaces through facilitating electron transfer and mass transport, nanoporous FeCo/CeO2−xNx 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.

Non-precious metal-based catalysts for water electrolysis to produce H2 under industrial conditions

“…The structural and chemical stability of MoC–Mo 2 C-790, as well as the strong binding strength of 17 N between MoC–Mo 2 C and Mo substrates, allow for long-term operation in both acidic and alkaline solutions and withstand the H 2 erosion. For high-efficiency OER, a lamella-heterostructured nanoporous FeCo/CeO 2− x N x (NP FeCo/CeO 2− x N x ) was constructed, 177 requiring just a 360 mV overpotential to drive more than 3900 mA cm −2 . At an overpotential of 300 mV, the current density of the catalyst can reach 1195 mA cm −2 , satisfying the requirements of industrial water electrolyzers (>500 mA cm −2 at an overpotential of <300 mV).…”

Recent progress in hierarchical nanostructures for Ni-based industrial-level OER catalysts

“…Some other species with hierarchical structures also deliver extraordinary behaviours toward the ICD OER, such as a self-supported hierarchical composite electrode composed of alternating nonporous bimetallic iron–cobalt alloy/hydroxide and cerium oxynitride (FeCo/CeO 2− x N x ) for the alkaline ICD OER with superstability for over 1000 h at ∼1900 mA cm −2 and reach >3900 mA cm −2 at 360 mV in 1 M KOH. 62…”

Critical challenges and opportunities for the commercialization of alkaline electrolysis: high current density, stability, and safety

“…12b). 156 During the rigorous oxygen evolution reaction (OER), Fe dissolution is an unavoidable process in FeCo/CeO 2− x N x . However, the dissolution rate of Fe in nanoporous FeCo/CeO 2− x N x was found to be approximately 0.477 μg h −1 , even at a high current density of approximately 1900 mA cm −2 .…”