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.

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Plasma electrolytic oxidation (PEO) can reduce the corrosion susceptibility of Mg alloys by producing a protective oxide layer. The present investigation examined the influence of PEO processing parameters on the corrosion resistance of the resulting coatings. Changes in the oxidation time, applied current density, and electrolyte temperature were shown to alter the thickness of the coating as well as its phase composition. Increasing the coating time was found to increase the thickness and uniformity of the coating. Application of a greater current density was found to increase the thickness of the outer layer, resulting in a more porous structure with reduced corrosion resistance. Elevating the temperature of the electrolyte resulted in partial dissolution of the coating, producing a thinner coating than that produced in an electrolyte at a lower temperature. The resistance to corrosion initiation was considered to be related to through-film pores in the coating, via electrochemical impedance modelling.