Introducing X-ray photoelectron spectroscopy for corrosion studies: A tool for elucidating interfacial composition and chemistry

Understanding, and potentially controlling, the properties of inorganic interfaces in aqueous environments requires the application of techniques capable of characterising their composition and chemistry. One technique that is widely applied in this domain is X-ray photoelectron spectroscopy (XPS), which is now considered by many researchers to be a key component of their characterisation toolbox. On this basis, an accessible introduction to X-ray photoelectron spectroscopy (XPS) is provided in this chapter, with a focus on its application for corrosion studies. Initially, we outline the basic physical processes underpinning XPS, and how these result in surface sensitivity and chemical specificity. We also discuss the limitations of the technique and adaptations to allow data acquisition in more real-world environments, alongside a description of key instrumentation. Subsequently, we provide guidance on the analysis of XPS data, with a particular emphasis on fitting of spectra, as well as approaches to quantification. In the latter part of the chapter, we demonstrate the capabilities of XPS for characterising surface layers formed by corrosion inhibitors in aqueous acidic solution.