Selective Oxidation From Toluene to Benzaldehyde via 4f-Orbital Involvement

Selective oxidation has been greatly challenging for the benzylic C─H bond from toluene to benzaldehyde. In this study, Sm³⁺ doped Bi₂WO₆ (Sm-BWO) nanosheets are constructed through in situ lattice substitution to establish spatially coupled dual-active sites with interfacial synergy, enabling a high toluene conversion rate of 8550 µmol·g⁻¹·h⁻¹ with high selectivity toward benzaldehyde (>86%). Mechanistic investigations reveal that Sm-doping induces oxygen vacancies (O_Vs) and Bi─O frustrated Lewis pairs (FLPs) for benzylic C─H dehydrogenation. The 4f orbital from localized Sm enables electron injection into π* antibonding orbitals of O₂. Orbital coupling between 4f of Sm and 2p of O creates a directional oxygen species transfer channel across the interface, delivering activated oxygen species for direct oxygenation of benzyl intermediate to benzaldehyde. The f-orbital catalysis demonstrates as a generalizable strategy for orchestrating O₂ activation for C─H functionalization. A unique perspective was provided on selective benzylic C─H oxidation by leveraging the f-orbital catalysis via inexpensive light rare earth.