15. Single Ru atoms with precise coordination on a monolayer layered double hydroxide for efficient electrooxidation catalysis

Wang, Z., Xu, S. M., Xu, Y., Tan, L., Wang, X., Zhao, Y., Duan, H.*, Song, Y. F.
Chem. Sci. 2019, 10, 378-384.
DOI: 10.1039/c8sc04480e

Abstract
The catalytic properties of single-atom catalysts (SACs) can be influenced largely by the chemical environment exerted by supports. Therefore, a precise location of the single atom is essential for understanding of the reaction mechanism and design of novel SACs. However, the preparation of SACs with a precise location remains a great challenge. Herein, we report a facile one-step method to synthesize single Ru atoms supported on a monolayer NiFe-layered double hydroxide (mono-NiFe). Detailed studies demonstrate that the single Ru atoms are not dispersed randomly in the LDH structure, but are uniquely located on the top of the Fe-metal atom of mono-NiFe via three oxygen atoms. Furthermore, these SACs prove to be highly active for the hydrazine electrooxidation reaction. Density functional theory calculations demonstrate that the single Ru atoms can stabilize the hydrazine electrooxidation intermediate with one unpaired electron (*N₂H₃ and *N₂H), thus lowering the reaction barrier for the rate-determining step. Moreover, the loading amount of single Ru atoms with a precise location can even go up to 7.0 wt% without any aggregation.