September 26, 2019
Journal Article

Understanding Heterolytic H2 Cleavage and Water-Assisted Hydrogen Spillover on Fe3O4(001)-Supported Single Palladium Atoms

Nassar Doudin
Simuck Yuk
Matthew Marcinkowski
Manh Nguyen
Jin-Cheng Liu
Yang Wang
Jun Li
Vassiliki-Alexandra Glezakou
Gareth Parkinson
Roger Rousseau
Zdenek Dohnalek
Zbynek Novotny
The high specific activity, novel properties, and cost effectiveness of single-atom catalysts (SAC) hold great promise and allow for new chemistry in numerous reactions. Here, we focus on fundamental understanding of the critical step in hydrogenation reactions, H2 activation, on a model SAC catalyst comprised of single Pd atoms on reconstructed Fe3O4(001). Using a combination of scanning tunneling microscopy and density functional theory we demonstrate that H2 dissociates heterolytically, ultimately yielding hydroxyls on, and excess charge in, the Fe3O4 support. The hydrogenation can be carried out to high coverages and ultimately leads to lifting of the Fe3O4 reconstruction and Pd reduction and destabilization. Water plays an important role in reduction of the hydrogen diffusion barrier, thereby facilitating redistribution of hydroxyls away from Pd. Our study demonstrates a distinct H2 activation mechanism on single Pd atoms and shows the importance of a reducible support that can facilitate charge transport away from the active site.

Revised: September 26, 2019 | Published: September 6, 2019

Doudin N.M., S.F. Yuk, M.D. Marcinkowski, M. Nguyen, J. Liu, Y. Wang, and Z. Novotny, et al. 2019. "Understanding Heterolytic H2 Cleavage and Water-Assisted Hydrogen Spillover on Fe3O4(001)-Supported Single Palladium Atoms." ACS Catalysis 9, no. 9:7876-7887. PNNL-SA-141193. doi:10.1021/acscatal.9b01425