Identification of Active Sites on High-Performance Pt/Al2O3 Catalyst for Cryogenic CO Oxidation

Exclusive Pt species supported on inert substrates have not achieved satisfactory performance for cryogenic CO oxidation because of the constraint of the competitive Langmuir–Hinshelwood process in which the strongly adsorbed CO inhibits the activation of O2. Here, we develop a catalyst of Pt nanoparticles on Al2O3 that exhibits extremely high activity with 100% CO conversion at −20 °C and orders of magnitude higher specific rate than current commercial catalysts. Detailed catalyst characterizations reveal the presence of metallic Pt sites and positively charged ones associated with the OH species in Pt/Al2O3. Both experimental data and theoretical calculations suggest that CO adsorbed on Pt(OH) kink sites reacts with OH species covering Pt0 terrace sites to release CO2. Afterward, O2 is facilely activated on terrace sites to regenerate OH. The presence of OH species and the synergy between Pt kink and terrace sites on the Pt species lead to an ultralow reaction barrier for CO oxidation.