Abstract
Identifying catalytically active structures or intermediates in homogeneous and heterogeneous catalysis is a formidable challenge. However, obtaining experimentally verified insight into the active species in heterogeneous catalysis is a tremendously challenging problem. Many highly advanced spectroscopic and microscopic methods have been developed to probe surfaces. In this discussion we employ a combination of spectroscopic methods to study two closely related systems from the heterogeneous (the silica-supported vanadium oxide VOx/SBA-15) and homogeneous (the complex K[VO(O2)Hheida]) domains. Spectroscopic measurements were conducted strictly in parallel for both systems and consisted of oxygen K-edge and vanadium L-edge X-ray absorption measurements in conjunction with resonance Raman spectroscopy. It is shown that the full information content of the spectra can be developed through advanced quantum chemical calculations that directly address the sought after structure-spectra relationships. To this end we employ the recently developed restricted open shell configuration interaction theory together with the time-dependent theory of electronic spectroscopy to calculate XAS and rR spectra respectively. The results of the study demonstrate that: (a) a combination of several spectroscopic techniques is of paramount importance in identifying signature structural motifs and (b) quantum chemistry is an extremely powerful guide in cross connecting theory and experiment as well as the homogeneous and heterogeneous catalysis fields. It is emphasized that the calculation of spectroscopic observables provides an excellent way for the critical experimental validation of theoretical results.
Highlights
Due to several strong assumptions needed for the connection between thermodynamics, kinetics and mechanism, the necessity for a more immediate connection between theory and experiment emerges. It is the aim of this paper to emphasize that such strong ties between theory and experiment can be established by combining a range of spectroscopic methods with the results of carefully calibrated theoretical spectroscopy
We have recently introduced the restricted open shell con guration interaction singles (ROCIS) method as a method of general applicability to interpret metal L-edge spectra of a large class of molecules, ranging from mononuclear complexes up to polymetallic clusters.[16,17,18,19]
A systematic computational protocol based on advanced theoretical spectroscopy was applied in order to extract the structural information of active catalytic centers in both homogenous and heterogeneous catalysis
Summary
A unified view on heterogeneous and homogeneous catalysts through a combination of spectroscopy and quantum chemistry†. Many highly advanced spectroscopic and microscopic methods have been developed to probe surfaces In this discussion we employ a combination of spectroscopic methods to study two closely related systems from the heterogeneous (the silica-supported vanadium oxide VOx/SBA-15) and homogeneous (the complex K[VO(O2)Hheida]) domains. It is shown that the full information content of the spectra can be developed through advanced quantum chemical calculations that directly address the sought after structure–spectra relationships. To this end we employ the recently developed restricted open shell configuration interaction theory together with the time-dependent theory of electronic spectroscopy to calculate XAS and rR spectra respectively. It is emphasized that the calculation of spectroscopic observables provides an excellent way for the critical experimental validation of theoretical results
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