Balancing activity, stability and conductivity of nanoporous core-shell iridium/iridium oxide oxygen evolution catalysts

Abstract

The selection of oxide materials for catalyzing the oxygen evolution reaction in acid-based electrolyzers must be guided by the proper balance between activity, stability and conductivity—a challenging mission of great importance for delivering affordable and environmentally friendly hydrogen. Here we report that the highly conductive nanoporous architecture of an iridium oxide shell on a metallic iridium core, formed through the fast dealloying of osmium from an Ir25Os75 alloy, exhibits an exceptional balance between oxygen evolution activity and stability as quantified by the activity-stability factor. On the basis of this metric, the nanoporous Ir/IrO2 morphology of dealloyed Ir25Os75 shows a factor of ~30 improvement in activity-stability factor relative to conventional iridium-based oxide materials, and an ~8 times improvement over dealloyed Ir25Os75 nanoparticles due to optimized stability and conductivity, respectively. We propose that the activity-stability factor is a key “metric” for determining the technological relevance of oxide-based anodic water electrolyzer catalysts.

Stable Active Sites on Ni12P5 Surfaces for the Hydrogen Evolution Reaction

“…However, Zhuang et al found that activity and stability do not always obey this relationship, and surface stability that is too high or too low corresponds to poor HER activities for metal or transition metal carbides . Recent experimental results also verify that balancing of the activity and stability is possible for nanoporous core‐shell iridium/iridium oxide for oxygen evolution catalysts . The results of the present study indicate that bridge Ni 2 Ni 3 of the (111)C is the most active (Δ G H* = 0) and unstable (6 coordination number).…”

Nickel Foam‐Supported Amorphous FeCo(Mn)−O Nanoclusters with Abundant Oxygen Vacancies through Selective Dealloying for Efficient Electrocatalytic Oxygen Evolution

“…Dendritic core‐shell NiFeCu metal/metal oxide and mesoporous Ni 60 Fe 30 Mn 10 catalysts by dealloying treatments require smaller overpotentials by 66 mV and 230 mV than the respective reference samples to drive a current density of 10 mA cm −2 in alkaline electrolyte . More importantly, a activity‐stability factor for well balancing the activity, stability and conductivity of the OER process has been established over a highly conductive nanoporous architecture of an iridium oxide shell on a metallic iridium core through fast dealloying of osmium from an Ir 25 Os 75 alloy . To date, the structural defects by selective alloy corrosion have received less attention and thus been scarcely reported.…”

Controlled Leaching Derived Synthesis of Atomically Dispersed/Clustered Gold on Mesoporous Cobalt Oxide for Enhanced Oxygen Evolution Reaction Activity

“…However, the electrocatalytic water splitting, which is considered to play a key role in the sustainable hydrogen production, has been largely constrained by sluggish anodic OER . While Ru and Ir are well known catalysts for OER, these catalysts are among the rarest elements and need to be replaced by relatively cheap and earth‐abundant alternatives . Cobalt oxide (Co 3 O 4 ) is one of the excellent candidates for substituting these high cost metal catalysts because of its high OER activity .…”