| Autor: |
Huang, Yi-Cheng, Yen, Hung-Yu, Lan, Liang-Wei, Dutta, D., Rahmah, A., Lai, Yu-Ling, Hsu, Yao-Jane, Kuo, Chien-Cheng, Wang, Jeng-Han, Luo, Meng-Fan |
| Předmět: |
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| Zdroj: |
Journal of Chemical Physics; 8/21/2021, Vol. 155 Issue 7, p1-11, 11p |
| Abstrakt: |
We studied the dissociation of water (H2O*, with * denoting adspecies) on atomic oxygen (O*)-covered Rh nanoclusters (RhO*) supported on a graphene film grown on a Ru(0001) surface [G/Ru(0001)] under ultrahigh-vacuum conditions and with varied surface-probe techniques and calculations based on density-functional theory. The graphene had a single rotational domain; its lattice expanded by about 5.7% to match the Ru substrate structurally better. The Rh clusters were grown by depositing Rh vapors onto G/Ru(0001); they had an fcc phase and grew in (111) orientation. Water adsorbed on the Rh clusters was dissociated exclusively in the presence of O*, like that on a Rh(111) single-crystal surface. Contrary to the case on Rh(111)O*, excess O* (even at a saturation level) on small RhO* clusters (diameter of 30–34 Å) continued to promote, instead of inhibiting, the dissociation of water; the produced hydroxyl (OH*) increased generally with the concentration of O* on the clusters. The difference results from more reactive O* on the RhO* clusters. O* on RhO* clusters activated the dissociation via both the formation of hydrogen bonds with H2O* and abstraction of H directly from H2O*, whereas O* on Rh(111)O* assisted the dissociation largely via the formation of hydrogen bonds, which was readily obstructed with an increased O* coverage. As the disproportionation (2 OH* → H2O* + O*) is endothermic on the RhO* clusters but exothermic on Rh(111)O*, OH* produced on RhO* clusters showed a thermal stability superior to that on the Rh(111)O* surface—thermally stable up to 400 K. [ABSTRACT FROM AUTHOR] |
| Databáze: |
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