title: Towards ALD thin film stabilized single-atom Pd1 catalysts.
abstract: Supported precious metal single-atom catalysts have shown interesting activity and selectivity in recent studies. However, agglomeration of these highly mobile mononuclear surface species can eliminate their unique catalytic properties. Here we study a strategy for synthesizing thin film stabilized single-atom Pd1 catalysts using atomic layer deposition (ALD). The thermal stability of the Pd1 catalysts is significantly enhanced by creating a nanocavity thin film structure. In situ infrared spectroscopy and Pd K-edge X-ray absorption spectroscopy (XAS) revealed that the Pd1 was anchored on the surface through chlorine sites. The thin film stabilized Pd1 catalysts were thermally stable under both oxidation and reduction conditions. The catalytic performance in the methanol decomposition reaction is found to depend on the thickness of protecting layers. While Pd1 catalysts showed promising activity at low temperature in a methanol decomposition reaction, 14 cycle TiO2 protected Pd1 was less active at high temperature. Pd L3 edge XAS indicated that the low reactivity compared with Pd nanoparticles is due to the strong adsorption of carbon monoxide even at 250 °C. These results clearly show that the ALD nanocavities provide a basis for future design of single-atom catalysts that are highly efficient and stable.
authors: Department of Chemical and Materials Engineering, University of Alabama in Huntsville, Huntsville, Alabama 35899, USA. yu.lei@uah.edu.
authors: Mar
authors: M
authors: Piernavieja-Hermida
authors: Department of Chemical and Materials Engineering, University of Alabama in Huntsville, Huntsville, Alabama 35899, USA. yu.lei@uah.edu.
authors: Zheng
authors: Z
authors: Lu
authors: Department of Chemical and Materials Engineering, University of Alabama in Huntsville, Huntsville, Alabama 35899, USA. yu.lei@uah.edu.
authors: Anderson
authors: A
authors: White
authors: Research Resources Center, University of Illinois at Chicago, Chicago, Illinois 60607, USA.
authors: Ke-Bin
authors: KB
authors: Low
authors: X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.
authors: Tianpin
authors: T
authors: Wu
authors: Energy Systems Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.
authors: Jeffrey W
authors: JW
authors: Elam
authors: Center for Nanophase Materials Sciences and Chemical Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors: Zili
authors: Z
authors: Wu
authors: Department of Chemical and Materials Engineering, University of Alabama in Huntsville, Huntsville, Alabama 35899, USA. yu.lei@uah.edu.
authors: Yu
authors: Y
authors: Lei