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Abstract

The growth of ZnO clusters supported by ZnO-bilayers on Ag(111) and the interaction of these oxide nanostructures with water have been studied by a multi-technique approach combining temperature-dependent infrared reflection absorption spectroscopy (IRRAS), grazing-emission X-ray photoelectron spectroscopy, and density functional theory calculations. Our results reveal that the ZnO bilayers exhibiting graphite-like structure are chemically inactive for water dissociation, whereas small ZnO clusters formed on top of these well-defined, yet chemically passive supports show extremely high reactivity - water is dissociated without an apparent activation barrier. Systematic isotopic substitution experiments using H216O/D216O/D218O allow identification of various types of acidic hydroxyl groups. We demonstrate that a reliable characterization of these OH-species is possible via co-adsorption of CO, which leads to a red shift of the OD frequency due to the weak interaction via hydrogen bonding. The theoretical results provide atomic-level insight into the surface structure and chemical activity of the supported ZnO clusters and allow identification of the presence of under-coordinated Zn and O atoms at the edges and corners of the ZnO clusters as the active sites for H2O dissociation.

Citation

Yu, Xiaojuan, et al. “Chemical Reactivity of Supported ZnO Clusters: Undercoordinated Zinc and Oxygen Atoms as Active Sites.” ChemPhysChem 21.23 (2020): 2553-2564.

@article{yu2020zno,
  title={Chemical Reactivity of Supported ZnO Clusters: Undercoordinated Zinc and Oxygen Atoms as Active Sites},
  author={Yu, Xiaojuan and Roth, Jannik P and Wang, Junjun and Sauter, Eric and Nefedov, Alexei and Hei{\ss}ler, Stefan and Pacchioni, Gianfranco and Wang, Yuemin and W{\"o}ll, Christof},
  journal={ChemPhysChem},
  volume={21},
  number={23},
  pages={2553--2564},
  year={2020},
  publisher={Wiley Online Library},
  doi={10.1002/cphc.202000747}
}