Propanol formation: top views of DFT optimized structures for (a) initial state: adsorbed propyl and hydroxyl radicals with C–O = 0.4 nm, (b) TS: adsorbed propyl and hydroxyl species with C–O = 0.215 nm, and (c) adsorbed propanol on a Ni(100) slab with C–O = 0.15 nm.