The advantages, challenges, and future possibilities for combining synchrotron-based X-ray techniques with vibrational spectroscopies are considered in this critical review. Particular emphasis is given to (1) quantifying structure and structural change—on a wide range of length scales—in working heterogeneous catalytic systems; (2) relating that change to chemical speciation occurring at the surface of the catalyst; and (3) determining how such change relates to the overall function of the catalyst material. We will consider those resources that exist today and suggest some possible future directions yet to be ventured into or demonstrated. Lastly, we will consider how the catalysis community interacts with, and uses the resources offered by, modern synchrotron radiation facilities and whether this current relationship provides the best and most inclusive means for the exploitation of these resources in this field of research (83 references).
Large datasets containing many spectra commonly associated with in situ or operando experiments call for new data treatment strategies as conventional scan by scan data analysis methods have become a time-consuming bottleneck. Several convenient automated data processing procedures like least square fitting of reference spectra exist but are based on assumptions. Here we present the application of multivariate curve resolution (MCR) as a blind-source separation method to efficiently process a large data set of an in situ X-ray absorption spectroscopy experiment where the sample undergoes a periodic concentration perturbation. MCR was applied to data from a reversible reduction-oxidation reaction of a rhenium promoted cobalt Fischer-Tropsch synthesis catalyst. The MCR algorithm was capable of extracting in a highly automated manner the component spectra with a different kinetic evolution together with their respective concentration profiles without the use of reference spectra. The modulative nature of our experiments allows for averaging of a number of identical periods and hence an increase in the signal to noise ratio (S/N) which is efficiently exploited by MCR. The practical and added value of the approach in extracting information from large and complex datasets, typical for in situ and operando studies, is highlighted.
Combination of in situRaman scattering with high-resolution XRD and XAS techniques has proven to be a powerful tool to elucidate the crystal growth of γ-Bi2MoO6 under hydrothermal conditions.
1 January 2023 in Journal of Synchrotron Radiation
A new heater design, capable of fast heating and cooling to and from >1000°C, has been developed at the Swiss–Norwegian Beamlines, European Synchrotron Radiation Facility, France. The design uses a SiC head to distribute heat, and resistive Si3N4 heat cartridges to provide heat.