Formation of Ni-O-H-S surface phases on cathodically charged Ni
By Jiang, Lai; Verkhoturov, Stanislav; Schweikert, Emile; Demkowicz, Michael J.
Published in Corrosion Science
2021
Abstract
We investigate the formation of surface phases on nickel (Ni) during cathodic charging in 1 M H2SO4 solution. Using complementary characterization techniques, we show that these phases are aggregated into filamentary structures with a thickness of ∼150 nm and ∼30% sample surface coverage. The phases are rich in Ni, O, H, and S, but free of C. Their surface potential is cathodic with respect to the surrounding Ni by ∼70 mV. We propose that these phases may be products of a reaction between the aqueous electrolyte and a metastable nickel surface hydride, assumed to form during cathodic charging. These findings stand to advance understanding of the catalytic activity of Ni cathodes, H uptake and embrittlement in Ni, and the onset of localized corrosion during cathodic charging.