Mechanism of Nickel–Iron Water Oxidation Electrocatalysts

Hotly debated these days is whether nickel or iron the active site in nickel–iron water oxidation electrocatalysts. We have previously argued that a likely candidate for highly materials because it can reach high-oxidation (high-ox) states at potentials relevant to splitting. Here, we further assert not an electrocatalysis materials. Our 3-fold argument supported by electrochemical measurements on rigorously planar electrodes produced pulsed laser ablation liquids: (1) cannot achieve high-ox aqueous environments potentials; (2) large steady-state concentrations of metal sites preclude them from being active, thereby indicating even more oxidizing moieties are critically important; and (3) unlike sites, documented experimentally neither rare nor unreasonably reactive.