Enhancement of Selective Catalytic Oxidation of Lignin β-O-4 Bond via Orbital Modulation and Surface Lattice Reconstruction.

Abstract

The orbital modulation and surface lattice reconstruction represent an effective strategy to regulate the interaction between catalyst interface sites and intermediates, thereby enhancing catalytic activity and selectivity. In this study, the crystal surface of Au-K/CeO₂ catalyst can undergo reversible transformation by tuning the coordination environment of Ce, which enables the activation of the C_β-H bond and the oxidative cleavage of the C_β-O and C_α-C_β bonds, leading to the cleavage of 2-phenoxy-1-phenylethanol. The t_2g orbitals of Au 5d hybridize with the 2p orbitals of lattice oxygen in CeO₂ via π-coordination, modulating the coordination environment of Ce 4 f and reconstructing the lattice oxygen in the CeO₂ framework, as well as increasing the oxygen vacancies. The interface sites formed by the synergy between Au clusters in the reconstructed Ce-O_L1-Au structure and doped K play dual roles. On the one hand, it activates the C_β-H bond, facilitating the enolization of the pre-oxidized 2-phenoxy-1-phenylethanone. On the other hand, through single-electron transfer involving Ce³⁺ 4f¹ and the adsorption by oxygen vacancies, it enhances the oxidative cleavage of the C_β-O and C_α-C_β bonds. This study elucidates the complex mechanistic roles of the structure and properties of Au-K/CeO₂ catalyst in the selective catalytic oxidation of lignin β-O-4 bond.