Selectivity of Ni-based surface alloys toward hydrazine adsorption: A DFT study with van der Waals interactions

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 Ni15/M1/Ni(1 1 1), Ni14/M2/Ni(1 1 1), Ni12/M4/Ni(1 1 1) and Ni8/M8/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 Ni8Fe8/Ni(1 1 1), Ni8Rh8/Ni(1 1 1), Ni15Ir1/Ni(1 1 1) and Ni14Ir2/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.