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|Title:||Water dissociation and KOH formation on potassium-covered MgO/Ru(001)|
|Authors:||Huang, H.H. |
|Source:||Huang, H.H.,Jiang, X.,Siew, H.L.,Chin, W.S.,Xu, G.Q. (1998-12-08). Water dissociation and KOH formation on potassium-covered MgO/Ru(001). Langmuir 14 (25) : 7217-7221. ScholarBank@NUS Repository.|
|Abstract:||The sequential adsorption and reaction of H2O wiht K on MgO thin films have been studied using TDS and XPS. Upon H2O adsorption on K/MgO at 100 K, two hydrated species of K+(H2O)n -(OH)- are formed, resulting in corresponding H2O-TDS peaks at 200 and 270 K, respectively. The thermal conversion from hydrated K to at hydrated KOH leads to H2 desorption at 190-220 K. The formation of KOH is evidenced by the O 1s bonding energies at 530.6-530.9 eV. Both additional K deposition and thermal activation favor H2O dissociation. Annealing the coadsorbed surface to 500-600 K results in desorption and decomposition of KOH. The coincident desorption of K2O, H2O, and K at θK > 0.3 ML strongly suggests the decomposition pathway 2KOH → K2O, which further produces K desorbing into the gaseous phase and oxygen being retained on the surface. The KH species formed during H2O dissociation is also evidenced by the coincident desorption of H2 and K at 470-490 K for θK ≥ 1 ML.|
|Appears in Collections:||Staff Publications|
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