Theoretical Study of Hydrogen Adsorption on Ruthenium Clusters

Abstract

The geometries, stabilities, electronic, and magnetic properties of hydrogen adsorption on Ru n clusters have been systematically investigated by using density functional theory with generalized gradient approximation. The result indicates the absorbed species does not lead to a rearrangement of the basic cluster. For n [ 2, three different adsorption patterns are found for the Ru n H 2 complexes: One H atom binds to the Ru top site, and another H binds to the bridge site for n = 3, 5, 6, 8; bridge site adsorption for n = 4; hollow site and top site adsorption for n = 7. The adsorption energies display oscillation and reach the peak at n = 2, 4, 7, implying their high chemical reactivity. The small electron transferred number between H atoms and Ru n clusters indicates that the interaction between H atoms and Ru n clusters is small. When H 2 is absorbed on the Ru n clusters, the chemical activity of corresponding clusters is dramatically increased. The absorbed H 2 can lead to an oscillatory behavior of the magnetic moments, and this behavior is rooted in the electronic structure of the preceding cluster and the changes in the magnetic moment are indicative of the relative ordering of the majority and minority LUMO's. The second order difference indicates 5 is magic number in Ru n H 2 and Ru n clusters.

The stabilization of Fe, Ru, and Os clusters upon hydrogenation

“…1 However, the ground state structure of Ru 2 in this work is 1.14 eV lower than previous work where H atoms are adsorbed on top of one Ru atom. 21 The Ru-H distance in Ru 2 , Ru 4 , and Ru 7 is calculated to be 1.61Å, 1.61Å, and 1.68 A, respectively, while H 2 adsorption energy on Ru 7 is higher than Ru 2 and Ru 4 . H atoms are adsorbed on the top and bridge sites of Ru atoms in Ru 3 , Ru 6 , and Ru 8 .…”

“…Aer Ru 4 , bare Ru clusters are more stable than H 2 adsorbed Ru clusters conrming the nding of previously reported results. 21 For the Os cases, the threshold of the stability change is the size of 3. A possible explanation of the stability change can be explained by the strength of H and Fe, Ru, and Os.…”

“…The interaction of small Ru clusters and H 2 was theoretically investigated. 21 However, there is a lack of experimental results for a simple RuH 2 system. The Ru based complex systems such as RuH 2 (CO) n (n ¼ 2-4) and RuH 2 (PPh 3 ) 4 have been reported.…”

Uncovering the Mechanism of the Hydrogen Poisoning on Ru Nanoparticles via Density Functional Theory Calculations

“…The FeRu solid solution exhibited a positive H 2 reaction order, attributed to a reduced overlap of Ru d-states with the s-states from H compared to pristine Ru(0001) [15]. Theoretically, the H atom binding [15][16][17] and its diffusion [18,19] on Ru surfaces and the H 2 dissociative adsorption on Ru nanoparticles [20][21][22] were studied extensively. Modulation-excitation infrared spectroscopy (MEIRS) measurements together with density functional theory (DFT) calculations revealed that the dissociation of activated H 2 molecules is more probable than their adsorption, leading to the hydrogenation of the surface of the Ru catalyst [23].…”

Efficient hydrogenation over single-site bimetallic RuSn clusters

“…18,19 Structurally, DFT-based calculations have shown that small Ru N clusters prefer to adopt cubic-like structures. [20][21][22][23] Sn N clusters have attracted attention mainly because of remarkable thermal properties; the melting temperature for small clusters appears to be higher than that of the bulk. 24 Regarding their structure, a transition from planar to 3D geometries occurs at Sn 4 (rhombohedral) to Sn 5 (trigonal bipyramid), whereas larger clusters tend to form prolate-like open structures.…”