In Situ Formation of Nano Ni–Co Oxyhydroxide Enables Water Oxidation Electrocatalysts Durable at High Current Densities

The oxygen evolution reaction (OER) limits the energy efficiency of electrocatalytic systems due to high overpotential symptomatic poor kinetics; this problem worsens over time if performance OER electrocatalyst diminishes during operation. Here, a novel synthesis nanocrystalline Ni–Co–Se using ball milling at cryogenic temperature is reported. It discovered that, by anodizing structure OER, Se ions leach out original structure, allowing water molecules hydrate Ni and Co defective sites, nanoparticles evolve into an active Ni–Co oxyhydroxide. This transformation observed operando X-ray absorption spectroscopy, with findings confirmed density functional theory calculations. resulting exhibits 279 mV 0.5 A cm?2 329 1 sustained for 500 h. achieved low mass loadings (0.36 mg cm?2) cobalt. Incorporating in anion exchange membrane electrolyzer yields current 1.75 V 95 h without decay performance. When integrated CO2-to-ethylene electrolyzer, record-setting full cell voltage 3 achieved.