Quantifying Surface Intermediate Concentrations on Working Heterogeneous Catalysts Using Corrected Surface Enhanced Raman Spectroscopy

Accurate quantification of surface intermediate concentrations on functioning catalysts is essential for shedding light on reaction mechanisms and designing improved catalysts. This is challenging to accomplish due to the elusive nature of these species and limitations of conventional surface characterization techniques under realistic reaction conditions. Surface-enhanced Raman spectroscopy (SERS) can overcome some limitations, but changes in catalyst surface properties during reactions can affect the intensity of SERS signals, hindering quantitative measurements. We show that, by employing an inert and stable probe molecule, we can correct for the variations in SERS intensity as a function of reaction conditions and quantify surface intermediate concentrations. We validated this method by quantifying oxygen intermediates in ethylene epoxidation over supported silver nanoparticles. This robust and transferable approach provides a powerful tool for reliable quantification of surface intermediates on heterogeneous catalysts.