Fig. 4: The exploration of the reaction mechanism and path. | Nature Communications

Fig. 4: The exploration of the reaction mechanism and path.

From: CO2 hydrogenation over Fe-Co bimetallic catalysts with tunable selectivity through a graphene fencing approach

Fig. 4

a Reaction path diagram. Fe species, red balls; Co species, light blue balls; K species, purple balls. b DFT calculation models of Fe5C2, Fe5C2/Co, and Fe5C2/Co2C. Substrate colors: Fe, pink; C, brown; Co, blue. c H2 adsorption models and adsorption energies over Fe5C2 and Fe5C2/Co models. Substrate colors: Fe, pink; C, brown; Co, blue; H, white. d Propylene and 1-Butene adsorption models and adsorption energies over Fe5C2/Co and Fe5C2/Co2C models. e H2-TPD profile (i) and three-dimensional H2-TPD diagram (ii). f DFT calculated proposed catalytic reaction pathway for propylene hydrogenation over Fe5C2 site and Fe5C2-Co site in the conditions of 320 °C. The reaction free energies (eV) are shown in the inset. The shaded parts represented the energy barriers of the speed-determining step. g C3H6-pulse transient hydrogenation profiles of the spent catalysts (C3H6 signal and C3H8 signal).

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