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

Jehad Abed, Shideh Ahmadi, Laura Laverdure, Ahmed Abdellah, Colin P. O'Brien, Kevin Cole, Pedro Sobrinho, David Sinton, Drew Higgins, Nicholas J. Mosey, Steven J. Thorpe*, Edward H. Sargent

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


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

Original languageEnglish (US)
Article number2103812
JournalAdvanced Materials
Issue number45
StatePublished - Nov 11 2021


  • CO reduction
  • PGM-free X-ray absorption spectroscopy
  • cryomilling
  • oxygen evolution reaction

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering


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