Surface Intermediates in Photocatalysis or in Plasma Assisted Catalysis by Operando Infrared Spectroscopy

Fourier Transform InfraRed spectroscopy (FTIR) is extensively used for the characterization of catalytic materials and for understanding catalytic reactions. Commercial instruments now offer very interesting time resolution that can provide important tools for catalytic materials. A general overview will be given. Examples of new applications will be presented in two main domains: plasma assisted catalysis and photocatalysis.

In plasma assisted catalysis, operando IR evidenced the efficiency of plasma for decomposing organic species and for the preparation of heterogeneous catalysts. Nanoparticles of zeolites were prepared easily, with included reduced metal nanoparticles. Operando IR showed the reactions at work, and the role of the surface species. The role of water for generating active radicals was measured quantitativelin in kinetic studies. It also gave the first evidence for the role of the catalyst surface in isopropanol decomposition on alumina [6].

A new reactor was built for operando IR in photocatalysis. This reactor was used for studying methanol photooxidation [8]. The real reaction mechanism was determined and meaningful intermediates were distinguished from spectator species, in particular using isotope labelling in the SSITKA method.