A first-principles study of hydrazine adsorption and decomposition on Pt(111) surface: The effect of partially dissociative H2O on decomposition process

• The intramolecular and intermolecular dehydrogenations of N 2 H 4 is systematically explored. • The water monomer in partially dissociative conformation is found to be the most favorable on Pt(111) surface. • The OH group can dramatically decrease the dehydrogenation energy barriers. Density functional theory with dispersion correction (DFT-D3) is used to investigate the adsorption and decomposition of hydrazine (N 2 H 4 ) on Pt(111) surface, and the effect of water on decomposition process is considered. The stable adsorption configurations and adsorption energies are obtained for hydrazine, water and intermediate species. The hydrazine decomposition is investigated in three kinds of pathways including intramolecular dehydrogenation and intermolecular dehydrogenation via H atom or OH group assistance. It is shown that the adsorption of water in partially dissociative conformation (H and OH radicals) is the most stable on Pt(111) surface for its largest adsorption energy. The OH group can greatly promote the decomposition of hydrazine by drastically decreasing the energy barriers of dehydrogenation reactions, which are closely related to the overall PDOS distribution shifts of their transition states. From thermodynamics and kinetics points of view, the favorable decomposition pathway of hydrazine may be N 2 H 4 +OH→N 2 H 3 +OH→NHNH+OH→NNH+OH→N 2 .