Unraveling Catalytic Reaction Mechanism by In Situ Near Ambient Pressure X-ray Photoelectron Spectroscopy

Probing surface chemistry during reactions closer to realistic conditions is crucial for the understanding of mechanisms in heterogeneous catalysis. Near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) is one of the state-of-the-art surface sensitive techniques used to characterize catalyst surfaces in gas phases. This Perspective begins with a brief overview of the development of the NAP-XPS technique and its representative applications in identifying the active sites at a molecular level. Next, recent in situ NAP-XPS investigations of several model catalysts in the CO2 hydrogenation reaction are mainly discussed. Finally, we highlight the major challenges facing NAP-XPS and future improvements to facilities for probing intermediates with higher resolutions under real ambient pressure reactions in heterogeneous catalysis.