Fig. 2
From: Heterogeneous Fe3 single-cluster catalyst for ammonia synthesis via an associative mechanism
The energy diagram for the first two steps of NH3 synthesis on Fe(211) C7 site. The black line is for the dissociative mechanism, where *N2 dissociates directly, and the blue line for the associative mechanism, where the N–N bond breaks only after hydrogenation to the *NNH species
