Interfacial Oxidation Steers Selective Lignin Depolymerization to Guaiacyl Monomers

Lignin valorization into high-value aromatic aldehydes and ketones offers a sustainable strategy for replacing fossil-derived chemicals; however, uncontrolled oxidation driven by freely diffusing radicals persistently hinders the selective production of phenolic monomers. Here, we develop an interface-confined oxidation strategy by immobilizing Cu0/Cu+ sites on lignin-derived wrinkled carbon (Cu/LNC), enabling spatial regulation of reactive oxygen species (ROS) within an H2O2-driven system. Cu/LNC selectively recovered 96.8% of the accessible G-derived aromatic monomers from calcium lignosulfonate at 140 °C, whereas the catalyst-free ROS system recovered only 59.2%. In situ Raman spectroscopy and radical-quenching experiments reveal that the confined surface ·OH radicals selectively deconstruct the heterogeneous lignin network. Complementary in situ UV-vis spectroscopy and intermediate-trapping experiments further demonstrate that the surface ·OH regulates the reaction pathway by directing controlled C–C bond cleavage to form aldehyde and ketone products while suppressing overoxidation. This strategy is readily extended to diverse industrial lignins, with product distributions governed by feedstock structure, providing a general platform for the selective production of renewable aromatic chemicals, especially for the highly selective production of G-type monomers.