Dehydrogenation mechanisms of ammonia borane catalyzed by Pd atoms adsorbed on an MgO(100) surface

作者：Tong, Mingqiong; Yin, Zhenfen; Wang, Yan^*; Chen, Guangju

来源：International Journal of Hydrogen Energy, 2013, 38(35): 15285-15294.

DOI：10.1016/j.ijhydene.2013.09.097

• BH3NH3 (AB)
• DFT/UB3LYP method
• Dehydrogenation
• Pd-2/Pd-4 atoms on MgO surface

The dehydrogenation of ammonia borane (BH3NH3) catalyzed by Pd supported on an MgO(100) surface was investigated using the DFT/UB3LYP method and an embedded cluster model. We found that BH3NH3 molecules can be initially adsorbed on 2-Pd atom clusters on the MgO surface (Pd-2/MgO) in two different configurations, and on 4-Pd atom clusters (Pd-4/MgO) in one configuration. One of the two BH3NH3-Pd-2/MgO configurations can dehydrogenate in a concerted pathway with a forward free energy barrier of 16.5 kcal/mol, and the other in a stepwise mechanism with forward barriers of 11.1 and 9.4 kcal/mol, respectively. However, only a stepwise dehydrogenation pathway was found for the single BH3NH3-Pd-4/MgO configuration, with a rate-controlling barrier of 12.6 kcal/mol. These results suggest that the BH3NH3 dehydrogenation mechanism and reaction barrier height can change with the size of the Pd clusters on the MgO(100) surface.

• 出版日期2013-11-22
• 单位北京师范大学