Philippine Science Letters
Phil. Sci. Lett. 2014 7 (1) 81-87
available online: March 22, 2014
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Received: September 19, 2013
Revised: January 27, 2014
Accepted: January 29, 2014
The effects of the incident angle on molecular hydrogen (H₂) dissociative adsorption on a defective platinum (Pt) surface are determined using density functional theory method. The potential energy is calculated as functions of the H₂ interatomic distance r and H₂ center of mass distance Z from the surface for different incident angles and approach sites. The potential energy surface for each incident angle and approach site is obtained by plotting the potential energy as functions of r and Z. Based on the potential energy surfaces, H₂ dissociative adsorption occurs for all the incident angles and approach sites considered, with one hydrogen (H) atom residing closer to the Pt surface than the other H atom. The activation barriers for H₂ approaching the top and hexagonal close packed sites are much lower than those obtained for H₂ approaching the vacant site. In general, the desorption energy is found to decrease as the incident angle of H₂ is increased.