Carbon-Supported Iron Phosphides: Highest Intrinsic Oxygen Evolution Activity of the Iron Triad

We compared the oxygen evolution reaction (OER) activity of carbon-supported iron triad metal phosphide nanoparticles using Fe-purified KOH electrolyte. We prepared these catalysts with nearly identical structural properties using an ammonia-assisted ambient hydrolysis deposition (AHD) method allowing us to explore how their compositions affect their OER activities. We discovered that iron phosphide is far superior to its counterparts with an onset potential lower by 150 mV. Furthermore, we found that the anodic voltammetric scan with associated oxidation of Fe­(II) in the phosphide generates OER active sites; however, ambient oxidation of iron phosphide prior to that anodic scan deactivates the catalyst.