posted on 2024-04-03, 18:36authored byWeiping Yang, Fuyuan Qi, Wenjing An, Haochen Yu, Shutong Liu, Peipei Ma, Rui Chen, Shuangxi Liu, Lan-Lan Lou, Kai Yu
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/Ce0.95M0.05O2−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 O2, achieving O2 activation through the π-electron feedback mechanism.
Remarkably, Pt/Ce–Ov–Y sites in Pt/Ce0.95Y0.05O2−δ with the highest delocalized
electron density exhibited the best O2 activation behaviors
and catalytic activity in the aerobic oxidation of 5-hydroxymethylfurfural.
This work reveals that the activation of O2 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.