Atomic Layer Deposition of Nickel Oxides as Electrocatalyst for Oxygen Evolution Reaction

In this study, we present atomic layer deposition (ALD) of nickel oxides (NiO_x) using a new nickel precursor, (methylcyclopentadienyl)(cyclopentadienyl)nickel (NiCp(MeCp)), and ozone (O₃) as the oxygen source. The process features a relatively short saturation pulse of the precursor (NiCp(MeCp)) and a broad temperature window (150-250 °C) with a consistent growth rate of 0.39 Å per cycle. The NiO_x film deposited at 250 °C primarily exhibits a polycrystalline cubic phase with minimal carbon contamination. Notably, the post-annealed ALD NiO_x film demonstrates attractive electrocatalytic performance on the oxygen evolution reaction (OER) by providing a low overpotential of 320 mV at 10 mA cm^-2, a low Tafel slope of 70.5 mV dec^-1, and sufficient catalytic stability. These results highlight the potential of the ALD process using the NiCp(MeCp) precursor for the fabrication of high-activity catalysts.