Application of Ambient‐Pressure X‐ray Photoelectron Spectroscopy for the In‐situ Investigation of Heterogeneous Catalytic Reactions

The desire to carry out X-ray photoelectron spectroscopy (XPS) measurements at elevated pressure conditions has existed for decades and numerous research groups have contributed to the development of a modern form of XPS that can be used at gas pressures up to about 7 mbar. This technique is currently known as ambient-pressure (AP) XPS. This chapter provides an overview of the historical development of AP-XPS addressing specific technical advances and their relevance. It provides examples of the application of AP-XPS. These examples demonstrate the versatility of this technique for the investigation of catalytically relevant systems ranging from structurally well-defined systems composed of adsorbates on single crystal surfaces and nanoparticles, the catalytic growth of nanotubes, to operating electrochemical cells and industrial heterogeneous catalysts.