Probing the transition state region in catalytic CO oxidation on Ru

Abstract

Femtosecond x-ray laser pulses are used to probe the carbon monoxide (CO) oxidation reaction on ruthenium (Ru) initiated by an optical laser pulse. On a time scale of a few hundred femtoseconds, the optical laser pulse excites motions of CO and oxygen (O) on the surface, allowing the reactants to collide, and, with a transient close to a picosecond (ps), new electronic states appear in the O K-edge x-ray absorption spectrum. Density functional theory calculations indicate that these result from changes in the adsorption site and bond formation between CO and O with a distribution of OC-O bond lengths close to the transition state (TS). After 1 ps, 10% of the CO populate the TS region, which is consistent with predictions based on a quantum oscillator model.

Solar-Powered Plasmon-Enhanced Heterogeneous Catalysis

“…In both studies, Au nanorods have been either fully covered or only tip-coated with the coupling metal. 3-D FDTD simulations showed that electric field amplification was localized at the tips of the Au nanorods in both the fully and tip-covered samples ( Figure 6F) [141]. The plasmonic photoactivity showed no substantial increment for the Pt or Pd fully covered Au nanorods.…”

“…The absorption wavelength of the plasmonic component can be tuned by adjusting simple parameters such as the kind of plasmonic metal, its shape, and size [32,137]. Simultaneously, the selective deposition of metallic catalytic active species at the LSPR field-enhanced sites can drastically reduce the amount of needed catalyst [141].…”

“…Due to optical properties similar to that of gold, metal nitrides such as ZrN and TiN ( Figure 7B) could be used to replace Au NPs in the vis-NIR region and to provide enhanced light harvesting and field concentration [101,102,[144][145][146][147]. Together with galliumdoped zinc oxide (GZO), showing plasmonic resonance in the 1400-2200 nm range [141], these alternative materials offer the possibility of covering a broadband spectrum to selectively activate chemical bonds.…”

“…Other important Pd-catalyzed cross coupling reactions for the formation of C-C bonds (e.g., Sonogashira, Stille, Hiyama, Ullmann, and Buchwald-Hartwig reactions) have been performed by using Pd-Au alloys under visible light illumination at lower temperature than that required by pure thermal-driven processes [139]. Au nanorods decorated with Pt or Pd nanocrystals have been tested as bimetallic catalysts for H 2 plasmon-driven production and for formic acid dehydrogenation reaction [140,141]. In both studies, Au nanorods have been either fully covered or only tip-coated with the coupling metal.…”

Ultrafast Dynamics of a Nucleobase Analogue Illuminated by a Short Intense X-ray Free Electron Laser Pulse

“…For selected applications, these qualities offer important advantages over conventional x-ray sources. Time-resolved spectroscopy on the time scale of femtoseconds to picoseconds allows us to monitor, for the first time, atoms and electrons in action [4][5][6][7][8][9][10][11][12][13][14]. For structural analysis, the extreme intensity focused into a couple of μm 2 transforms single-shot diffraction imaging of biomolecules and nanosize objects from a remote goal into a tangible reality [15][16][17][18][19].…”