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Operando diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) is combined with online mass spectrometry (MS) to help to resolve a long-standing debate concerning the active phase of RuO2 supported on rutile TiO2 (RuO2@TiO2) during the CO oxidation reaction. DRIFTS has been demonstrated to serve as a versatile probe molecule to elucidate the active phase of RuO2@TiO2 under various reaction conditions. Fully oxidized and fully reduced catalysts serve to provide reference DRIFT spectra, based on which the operando CO spectra acquired during CO oxidation under various reaction conditions are interpreted. Partially reduced RuO2@TiO2 was identified as the most active catalyst in the CO oxidation reaction. This is independent of the reaction conditions being reducing or oxidizing and whether the starting catalyst is the fully oxidized RuO2@TiO2 or the partially reduced RuO2@TiO2. [ABSTRACT FROM AUTHOR]

A rational synthetic approach is introduced to enable hydrogen insertion into oxides by forming a solid solution of a reducible oxide with a less reducible oxide as exemplified with RuO2 and TiO2 (Ru_x, a mixture of x% RuO2 with (100−x)% TiO2). Hydrogen exposure at 250 °C to Ru_x (Ru_x_250R) results in substantial hydrogen incorporation accompanied by lattice strain that in turn induces pronounced activity variations. Here, we demonstrate that hydrogen incorporation in mixed oxides promotes the oxidation catalysis of propane combustion with Ru_60_250R being the catalytically most active catalyst. [ABSTRACT FROM AUTHOR]

We combine operando diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) with on-line mass spectrometry (MS) to study the correlation between the oxidation state of titania-supported IrO2 catalysts (IrO2@TiO2) and their catalytic activity in the prototypical CO oxidation reaction. Here, the stretching vibration of adsorbed COad serves as the probe. DRIFTS provides information on both surface and gas phase species. Partially reduced IrO2 is shown to be significantly more active than its fully oxidized counterpart, with onset and full conversion temperatures being about 50 °C lower for reduced IrO2. By operando DRIFTS, this increase in activity is traced to a partially reduced state of the catalysts, as evidenced by a broad IR band of adsorbed CO reaching from 2080 to 1800 cm−1. [ABSTRACT FROM AUTHOR]