Use of oxygen/nickel ratios in the XPS characterisation of oxide phases on nickel metal and nickel alloy surfaces

The O/Ni ratios derived from the X-ray photoelectron (XP) spectra of a number of well-characterised Ni oxides were calculated and found to correspond well to the expected O/Ni ratios for these oxides. The measured ratios, combined with the characteristic XP spectra, provide a higher level of confidence to the assignment of O 1s chemical species, particularly for surfaces with multiple phases present. As examples of this, we discuss the additional information imparted by O/Ni ratios measured for oxides that were electrochemically grown on Ni and NiCr-20% alloy surfaces. (c) 2012 Elsevier B.V. All rights reserved.