AVS 65th International Symposium & Exhibition
    Fundamental Discoveries in Heterogeneous Catalysis Focus Topic Thursday Sessions
       Session HC+SS-ThA

Paper HC+SS-ThA1
Hydrogen Adsorption and Reaction on RuO2(110) Surface

Thursday, October 25, 2018, 2:20 pm, Room 201A

Session: Bridging Gaps in Heterogeneously Catalyzed Reactions
Presenter: Zdenek Dohnalek, Pacific Northwest National Laboratory
Authors: A. Dahal, Pacific Northwest National Laboratory
I. Lyubinetsky, Pacific Northwest National Laboratory
Z. Dohnalek, Pacific Northwest National Laboratory
Correspondent: Click to Email
Ruthenium dioxide is used extensively as a co-catalyst in a wide range of photocatalytic water splitting systems. As such, understanding how it promotes the evolution of hydrogen and oxygen is of high importance. In our studies, we employed scanning tunneling microscopy in combination with moleculear beam scattering and temperature programmed desorption studies to follow adsorption, reaction, and thermal evolution of hydrogen on a model RuO2(110). In our temperature-dependent studies, we find that at low coverages (H2/Ru < 0.2) H2 dissociates heterolytically and forms hydride-hydroxyl pairs below 100 K. At higher coverages (H2/Ru > 0.2), H2 adsorbed on Ru sites neighboring the hydride-hydroxyl pairs chemisorbs molecularly. Upon annealing the hydride species convert to hydroxyls and most of the chemisorbed H2 desorbs. Upon heating, the low and high H2 covered surfaces transform to partially and fully hydroxylated surface, respectively, above 250 K. Molecular beam scattering studies reveal that the adsorption probability of hydrogen on this surface is strongly temperature-dependent, decreasing from ∼0.4 at 25 K to <0.01 at 300 K. These combined studies unravel a complete adsorption and dissociation mechanism of H2 on this model ruthenium dioxide surface.