We investigate the formation of surface phases on nickel (Ni) during cathodic charging in 1M H2SO4 solution. Using complementary characterization techniques, we show that these phases are aggregated into filamentary structures with a thickness of ~150nm and ~30% sample surface coverage. The surface phases grow with increasing overpotential and eventually reach full coverage. They appear to be thermodynamically stable in air but are also easily removed by ultrasonication. The phases are rich in Ni, O, H, and S, but free of C. Finally, the surface potential of these phases is cathodic with respect to the surrounding Ni by ~120mV. 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.This research was supported by NPRP grant #&nbsp;11S-1129-170045 from the Qatar National Research Fund (a constituent member of the Qatar Foundation). The statements made herein are solely the responsibility of the authors. This project was carried out using resources at the Texas A&amp;M University Materials Characterization Facility. We acknowledge the assistance of A. Bandyopadhyay with XRD measurements, W. Serem with SKPFM, D. Zhao with EBSD and EDS, and H. Hlushko with ATR-FTIR. SIMS measurements were supported by NSF grant CHE-130812

Formation of Ni-O-H-S Surface Phases on Cathodically Charged Ni

Paper Proceedings: https://asmedigitalcollection.asme.org/PVP/PVP2021/volume/85314

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