Enhanced CO Oxidation on PtOx Raft Species Synthesized via Citric Acid-Assisted Electrostatic Adsorption

Abstract

Platinum-based catalysts have attracted considerable attention for CO oxidation, with their activity critically dependent on the nanostructures of Pt species. Herein, raft-structured PtOx species on CeO2 support (Pt/CeO2-CA) were successfully prepared via a citric acid-assisted strong electrostatic adsorption (SEA) method, which leveraged competitive adsorption between noble metal precursors and organic compounds. The Pt/CeO2-CA catalyst exhibits a T50 (temperature for 50% CO conversion) over 120 °C lower than those of Pt single atoms and PtOx clusters-based catalysts, and the lowest apparent activation energy among the catalysts investigated, as well as reported analogues, demonstrating its excellent activity in CO oxidation. Combined catalyst characterization and density functional theory (DFT) calculations demonstrate enhanced CO adsorption on PtOx rafts with respect to Pt/CeO2 reference catalysts composed of Pt single atoms or PtOx clusters, and favored CO interaction with O* atoms from PtOx rafts and the CeO2 surface. We propose that this mitigates CO poisoning effects by circumventing competitive adsorption with O2, thereby accelerating the catalytic reaction. Our findings highlight promising design strategies for tuning the morphology of supported noble metal (oxide) nanostructures to further enhance their catalytic performances.