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

作者：Zhao, Xin; Fang, Ruiqi^*; Wang, Fengliang; Kong, Xiang-Peng; Li, Yingwei^*

来源：ACS Catalysis, 2022, 12(14): 8503-8510.

DOI：10.1021/acscatal.2c02361

• hetero-single-atoms
• biomass
• metal-organic frameworks
• oxidative cleavage
• 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 In2O3 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 Ir1Cu1-In2O3 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.