CO adsorption on hydrogen saturated Ru(0001)

Abstract

The interaction of CO with the Ru(0001)(1ϫ1)H surface has been studied by density functional theory ͑DFT͒ periodic calculations and molecular beam techniques. The hydrogen (1ϫ1) phase induces an activation barrier for CO adsorption with a minimum barrier height of 25 kJ mol Ϫ1 . The barrier originates from the initial repulsive interaction between the CO-4 and the Ru-d 3z 2 -r 2 orbitals. Coadsorbed H also reduces the CO adsorption energy considerably and enhances the site preference of CO. On a Ru͑0001͒͑1ϫ1͒H surface, CO adsorbs exclusively on the atop position.

Coadsorption of Hydrogen and CO on Hydrogen Pre‐Covered PtRu/Ru(0001) Surface Alloys

“…Here it may be also noted that the detected CO amount does not increase significantly with larger subsequent CO exposures (beyond 37.5 L) when dosing at~100 K. It was demonstrated by Riedmüller et al that non-activated CO adsorption in a saturated H ad layer on Ru(0001) can only proceed at defects of the (1 1) H ad layer, such as coadsorbed CO molecules. [27,28] This process leads to the formation of small CO islands embedded in the H ad layer. [28] In contrast, adsorption of CO on a perfect (1 1) H ad layer is an activated process with a minimum activation barrier of~25 kJ mol…”

“…[26,27] The integration of the TPD spectra shows that the possibility of CO adsorption on a D ad saturated surface leads to an extremely high total adsorbate coverage: 0.89 ML D ad + 0.19 ML CO ad [corresponding to 89 % of q D (Sat) + 28 % of q CO (Sat) for the two adsorbates on the surface alone]. In fact, a similar result is also observed for all other coadsorbed layers with smaller D ad pre-coverages (and consequently higher CO ad coverage).…”

“…[26][27][28] Preferential adsorption of further CO molecules in the vicinity of already adsorbed CO molecules leads to the formation of small CO islands in the H ad layer. [28] Under the conditions of most studies, [25,29] the formation of segregated islands (of the two adsorbate species) seems to be the general case, although the encirclement of isolated CO molecules by subsequently adsorbed hydrogen was reported for small CO coverages at low temperatures ( 100 K).…”

CO Blocking of D2 Dissociative Adsorption on Ru(0001)

“…[12,13] The present study follows up on our previous investigation of the dynamics of H 2 /D 2 dissociation on bare Ru(0001). [27] Herein, we probe the dynamics of D 2 dissociation on CO-covered Ru(0001).…”

Evidence of stable high-temperature Dx-CO intermediates on the Ru(0001) surface

“…10,11 CO was found to displace and ultimately drive the H-atoms off the surface. In the process, stable CO-islands were formed in a "sea" of hydrogen.…”