A Density Functional Theory Investigation of Ammonia Oxidation on the M-Doped β-Ni(OH)₂ (M = Cr, Co, Cu, Fe) Surfaces

The ammonia oxidation reaction (AOR) has applications as a sustainable energy source and in wastewater remediation. Nickel based catalysts for the AOR reaction are ideal as they are cost efficient, have longer lifetimes than more expensive alternatives, and can produce value-added products. Dopants can be applied to these nickel catalysts to further increase their value. This work explores the effects on reaction potentials when β-Ni(OH)2 is doped with chromium, cobalt, copper, or iron using density functional theory to model the AOR. Limiting potentials for dinitrogen production improved when β-Ni(OH)2 was doped with chromium and cobalt. Limiting potentials for nitrite production remained consistent when β-Ni(OH)2 was doped with cobalt or iron. Compared with the pristine β-Ni(OH)2 surface, there was no improvement in the limiting potential of nitrate formation for any of the doped surfaces. This research begins to reveal the importance of exploring dopant addition to β-Ni(OH)2 as a method of improving the catalyst activity for the AOR.