Zirconia-Supported ZnO Single Layer for Syngas Conversion Revealed from Machine-Learning Atomic Simulation.

Abstract

ZnZrO ternary oxide represents a prominent catalytic system, identified recently for syngas conversion and CO2 reduction via OX-ZEO technology. One intriguing observation of the ZnZrO catalyst is the very low amount of Zn required for achieving high activity, which challenges the current views on the active site of binary oxide catalysts. Herein, we demonstrate, via machine-learning-based atomic simulation, that the structure evolution of the ZnZrO system in synthesis can be traced from bulk to surface, which leads to the identification of the active site of the ZnZrO catalyst. Theory shows that an unprecedented single-layer Zn-O structure can adhere strongly to the monoclinic ZrO2 minority (001) surface, forming a stable oxide-on-oxide interface Zn-O/M(001). The single-layer Zn-O can convert syngas to methanol with a high turnover frequency (7.38 s-1) from microkinetics simulation. Electron structure analyses reveal that the pentahedron [ZnO4] in Zn-O/M(001) enhances the surface electron donation to promote the catalytic activity.