First Principles Calculations of Electrochemically Controlled Hydrogen Mobility and Uptake at the Ni(111)H2O Interface.

Taylor, C. ; Kelly, R. ; Neurock, M.

Technical Information Center Oak Ridge Tennessee

关键词: Hydrogen;    Nickel;    Uptake;    Mobility;    Water;   

RP-ID  :  DE2006875455

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

The binding of hydrogen on Ni(111) in the presence of an water is considered using both a bilayer and a saturated model of the solvent environment. The presence of a water bilayer did not change the binding energies or geometry of hydrogen on the Ni(111) compared to adsorption in ultra-high vacuum. Using the saturated model (four bilayers over the surface) we also monitored the change in hydrogen binding as a function of electrochemical potential. Binding energies for hydrogen at the hcp and octahedral sites shifted endothermically as the potential was made more anodic, indicating that reductive partial charge transfer occurs. Binding at the tetrahedral site was found to be partially oxidizing. Calculation of vibrational modes allowed the extrapolation of ab initio results to ambient and elevated temperatures. Surface Pourbaix diagrams were constructed illustrating the stability of various phases on the Ni(111) surface as a function of pH and potential.