Metal Oxide-Stabilized Hetero-Single-Atoms for Oxidative Cleavage of Biomass-Derived Isoeugenol to Vanillin

Hetero-single-atom (hetero-SA) catalysts provide extensive possibilities for advanced catalysis, while their fabrication is still a challenging task to date. Here, we report an in-situ deposition strategy for the immobilization of isolated hetero-SAs into a metal-oxide support. Systematic characterizations including X-ray absorption spectroscopy and spherical aberration-corrected Z-contrast imaging demonstrate the atomic dispersion of Ir and Cu atoms in In 2 O 3 stabilized by covalent Ir–O and Cu–O bonds, and the electron transfer is clearly observed by differential phase contrast-scanning transmission electron microscopy. The obtained Ir 1 Cu 1 –In 2 O 3 composite exhibits good catalytic performances in the selective oxidative cleavage of isoeugenol to vanillin, achieving 90.5% vanillin yield under mild conditions, far surpassing the those of Ir- and Cu-based SA counterparts. Density functional theory studies uncover the reaction mechanisms, that is, the adjacent Cu sites enhance the charge accumulation over the Ir sites, leading to facilitated O 2 adsorption and disassociation. Besides, Cu sites also play critical roles in accelerating the subsequent oxidative reaction due to the lowered energy barriers.