fig5

Figure 5. (A) Ni-Cu-Fe-OOH and the schematic illustration of the ammonia oxidation process; (B) The energy barriers of the different reaction steps of the N - N mechanism in Ni-Cu-Fe-OOH and Ni-Cu-OOH. The inset figure shows the energy barrier of the bifurcation step of the G-M mechanism and the N + N mechanism in the Ni-Cu-Fe-OOH system. Charge difference (C) in Ni-Cu-OOH system; and (D) Ni-Cu-Fe-OOH system (purple corresponds to charge accumulation, while yellow corresponds to charge depletion)^[111]. This figure is quoted with permission from Zhu et al.