Fig. 2: Surface phase diagrams.
From: A spin promotion effect in catalytic ammonia synthesis
a–d Top and side view of adsorption structures of M*/(MO)*/(MOH)*/(MN)* on the Ru(\(10\bar{1}5\)) surface. M means metallic promoter atom. Green, purple, red, yellow, and blue spheres represent Ru, promoter M, oxygen, hydrogen, and nitrogen atoms. e–j Phase diagrams of Cs, K, Li, Ba, Ca and La promoted Ru in equilibrium with their oxides, hydroxides hydrides, nitrides or amides under reaction conditions. Bulk species are shown as dashed lines, while adsorbed species are shown as full lines and identified by a *. A typical DFT uncertainty of ±0.2 eV is shown shaded for the adsorbed species. The reaction conditions are T = 673 K, H2 = 7.5 bar, NH3 = 0.1 bar (N2 conversion of 2%), PH2O = 10−7 bar, chosen to simulate an extremely dry reactant gas. All data used in the figure can be found in Supplementary Tables 2–4.
