Insights into the substitutional chemistry of La1−xSrxCo1−yMyO3 (M = Pd, Ru, Rh, and Pt) probed by in situ DRIFTS and DFT analysis of CO oxidation

We report the detailed surface chemistry of platinum, palladium, rhodium, and ruthenium substituted into lanthanum strontium cobaltate perovskite catalysts toward CO oxidation. The catalysts were synthesized by the solution combustion method and characterized in detailed using a series of techniques. To explore the effect of noble metal ion substitution on CO oxidation, surface intermediates were probed by operando diffuse reflectance infrared Fourier transform spectroscopy. It was recognized that La<inf>1−x</inf>Sr<inf>x</inf>Co<inf>1−y</inf>Rh<inf>y</inf>O<inf>3</inf> and La<inf>1−x</inf>Sr<inf>x</inf>Co<inf>1−y</inf>Pd<inf>y</inf>O<inf>3</inf> show the best activities for the reaction. DFT calculations were set up to unravel the details of the surface phenomena responsible for altering the CO oxidation activity upon noble metal ion substitution. The computational analysis conclusively demonstrated the experimentally hypothesized role of surface carbonate formation and revealed the altered mechanism for CO oxidation over the synthesized perovskites upon noble metal ion substitution.