CO oxidation over Pt/Cr1.3Fe0.7O3 catalysts: Enhanced activity on single Pt atom by H2O promotion

Abstract A series of Pt/Cr1.3Fe0.7O3 catalysts were tested for CO oxidation, and the activities are improved by the presence of H2O. Such improvement is more significant on the single atom 0.2Pt/Cr1.3Fe0.7O3 than on the 2Pt/Cr1.3Fe0.7O3 containing Pt nanoparticles, with turnover frequencies of 0.396 and 0.094 s−1 at 60 °C under 1% CO + 1% O2 + 10% CO2 + 10% H2O, respectively. In-situ diffuse reflectance infrared Fourier transform spectroscopic study on these catalysts suggests that the promoting effect of H2O is due to the facile reaction between adsorbed CO and surface hydroxyl groups via H2O dissociation. Kinetic investigation reveals that the 0.2Pt/Cr1.3Fe0.7O3 gives a higher intrinsic rate constant than the 2Pt/Cr1.3Fe0.7O3 (9.23 × 10−5 versus 4.50 × 10−5 mol g−1 s−1 at 60 °C) for the formation of formate intermediate due to its weaker CO adsorption strength, which explains the more significant H2O promotion on the single atom Pt catalyst.