Modulated Structure-Electronic Coupling at Pt/CeOx-TiO2 Interfaces Boosts Low-Temperature Preferential CO Oxidation.

Preferential oxidation, PROX, of residual CO in a hydrogen-rich synthetic gas is the final stage of industrial hydrogen production and purification. However, selectively oxidizing around 1 vol. % of CO without consuming hydrogen is technically challenging. Here, we use Pt single atoms (SAs) stabilized on CeOx-TiO2 supporting oxides toward PROX of CO. Based on a combined study of density functional theory calculations and in situ spectroscopic analyses, we identified the delicate electronic states of the reaction centers. The bifunctional nature of the spatially separated Pt-O-Ti and Pt-O-Ce sites promoted selective PROX of CO. The preferentially adsorbed hydrogen at the Pt-O-Ti site behaves as an activity regulator, donating electrons to Pt, thus reducing Pt-SAs. The oxygen ion at the Pt-O-Ce interface actively oxidizes the weakly adsorbed CO on reduced Pt-SAs. The unique structural and electronic ensembles at the Pt-CeOx-TiO2 interfaces suppress hydrogen consumption but, instead, promote the PROX of CO under hydrogen-rich conditions with high specific mass activity and 100 % selectivity for CO2 at below 100°C. We present a representative case of using electronic modulation of Pt-SAs under reaction conditions, enabled by the unique structural ensemble of Pt-oxide interfaces, to activate Pt-SAs dynamically.