Fig. 6. Investigations on reaction paths of 4-NS hydrogenation.

In situ FT-IR spectra of 4-NS hydrogenation in the presence of a monometallic Ni, b monometallic Ru, c 0.4 wt.% RuNi SAA, and d 2 wt.% RuNi, recorded within 1700–1240 cm^–1 by flowing H₂ as a reaction gas after 0, 3, 6, 9, and 12 min, respectively. ‘a. u.’ denotes arbitrary units. Potential energy profiles and corresponding optimized structures for C=C hydrogenation and N–O scission in 4-NS over e Ni(111), and f RuNi SAA(111) surface. Ru, violet; Ni, green; C, orange; O, red; N, blue; H, white. ‘ads’, ‘IS’, ‘TS’ and ‘FS’ represent the adsorption state, initial state, transition state, and final state, respectively.