Local Electronic Structure Modulation of Interfacial Oxygen Vacancies Promotes the Oxygen Activation Capacity of Pt/Ce_1–<i>x</i>M_<i>x</i>O_2−δ

Abstract

The asymmetric oxygen vacancies on the surface of doped oxides and at the interface between the metal and oxide are commonly regarded as the real active sites for the molecular oxygen activation reaction, owing to their unique electronic perturbation properties. However, the essential rules for modulating the local electronic structure of oxygen vacancies to promote the oxygen activation capacity are still ambiguous. In this work, a series of interfacial oxygen vacancy sites, Pt/Ce–Ov–M (Ov, oxygen vacancy, M = Y, La, Pr, and Nd), with different local coordination environments were constructed based on Pt/Ce 0.95 M 0.05 O 2−δ materials. The experimental data and theoretical calculation results prove that the interfacial Pt/Ce–Ov–M site can capture electrons from Pt d-bands and M d- and f-bands, acting as an electron enrichment center. The elevated M d-band center upward to the Fermi level can significantly boost the electron transfer from d-bands to the unoccupied π2p* orbital of O 2, achieving O 2 activation through the π-electron feedback mechanism. Remarkably, Pt/Ce–Ov–Y sites in Pt/Ce 0.95 Y 0.05 O 2−δ with the highest delocalized electron density exhibited the best O 2 activation behaviors and catalytic activity in the aerobic oxidation of 5-hydroxymethylfurfural. This work reveals that the activation of O 2 over metal-oxide catalysts is highly dependent on the interfacial electron transfer and d/f-orbital valence-electron modulation, providing more insights into the effect of oxygen vacancy-localized electronic perturbation on the oxygen activation performance.