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We use dispersion corrected DFT calculations (DFT + D3) to investigate the selectivity of Ni-based surface alloys toward hydrazine adsorption. A series of Ni–M (M = Fe, Pt, Ir, Pd and Rh) alloy films were investigated, namely Ni 15 /M 1 /Ni(1 1 1), Ni 14 /M 2 /Ni(1 1 1), Ni 12 /M 4 /Ni(1 1 1) and Ni 8 /M 8 /Ni(1 1 1). Our results show that the doped atoms of Ir, Rh and Fe provide stronger adsorption sites than the Ni atom on the Ni(1 1 1) surface, while the doped atoms of Pt and Pd provide weaker adsorption sites. By analyzing the most favorable adsorption of hydrazine on Ni–M alloy surfaces we found that Ni 8 Fe 8 /Ni(1 1 1), Ni 8 Rh 8 /Ni(1 1 1), Ni 15 Ir 1 /Ni(1 1 1) and Ni 14 Ir 2 /Ni(1 1 1) present enhanced adsorption properties if compared to the pure Ni(1 1 1) surface, and seem to be better candidates for hydrazine catalysis, which are in agreement with that found by experiments. The correlation between d-band center position and adsorption energies of top modes in the Ni or doped atom has been calculated at DFT + D3 level to provide further insight into the Ni-based surface alloy properties for hydrazine adsorption. [ABSTRACT FROM AUTHOR]

In recent years, metal nanoparticles were found to be excellent catalysts for hydrogen generation from hydrazine for chemical hydrogen storage. In order to gain a better understanding of these catalytic systems, we have simulated the adsorption of hydrazine on rhodium nanoparticles surfaces by density functional theory (DFT) calculations with dispersion correction, DFT-D3 in the method of Grimme. The rhodium nanoparticles were modeled by the Rh(1 1 1) surface, in addition, the adsorptions at corners and edges sites of nanoparticles were considered by using rhodium adatoms on the surfaces. The calculations showed that hydrazine binds most strongly to the edge of nanoparticle with adsorption energy of −2.48 eV, where the hydrazine bridges adatoms of edge with the molecule twisted to avoid a cis structure; similar adsorption energy was found at the corner of nanoparticle, where the hydrazine bridges corner atom and surface atom with gauche configuration. However, we found that inclusion of the dispersion correction results in significant enhancement of molecule–substrate binding, thereby increasing the adsorption energy, especially the adsorption to the Rh(1 1 1) surface. The results demonstrate that the surface structure is a key factor to determine the thermodynamics of adsorption, with low coordinated atoms which providing sites of strong adsorption from the surface. [ABSTRACT FROM AUTHOR]