Interfaces in heterogeneous catalytic reactions: Ambient pressure XPS as a tool to unravel surface chemistry

In this article we provide a summary of the recent development of ambient pressure X-ray photoelectron spectroscopy (AP-XPS) and its application to catalytic surface chemistry. The methodology as well as significant advantages and challenges associated with this novel technique are described. Details about specific examples of using AP-XPS to probe surface chemistry under working reaction conditions for a number of reactions are explained: CO oxidation, water-gas shift (WGS), CO2 hydrogenation, dry reforming of methane (DRM) and ethanol steam reforming (ESR). Finally, we discuss insights into the future development of the AP-XPS technique and its applications.