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Ab initio studies of hydrogen desorption from low index magnesium hydride surface |
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| Authors: | AJ Du Sean C Smith XD Yao GQ Lu |
| Institution: | a Centre for Computational Molecular Science, Chemistry Building 68, The University of Queensland, QLD 4072, Brisbane, Australia b ARC Centre for Functional Nanomaterial, School of Engineering, The University of Queensland, QLD 4072, Brisbane, Australia c School of Engineering, James Cook University, Townsville, QLD 4811, Australia |
| Abstract: | The low index Magnesium hydride surfaces, MgH2(0 0 1) and MgH2(1 1 0), have been studied by ab intio Density Functional Theory (DFT) calculations. It was found that the MgH2(1 1 0) surface is more stable than MgH2(0 0 1) surface, which is in good agreement with the experimental observation. The H2 desorption barriers vary depending on the crystalline surfaces that are exposed and also the specific H atom sites involved - they are found to be generally high, due to the thermodynamic stability of the MgH2 system, and are larger for the MgH2(0 0 1) surface. The pathway for recombinative desorption of one in-plane and one bridging H atom from the MgH2(1 1 0) surface was found to be the lowest energy barrier amongst those computed (172 KJ/mol) and is in good agreement with the experimental estimates. |
| Keywords: | Ab initio density functional calculations Desorption Surface relaxation |
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