The interaction of hydrazine with an Rh(1 1 1) surface as a model for adsorption to rhodium nanoparticles: A dispersion-corrected DFT study

Abstract

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(111) 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 −2.48eV, 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(111) 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.