The kinetic model was built based on all reaction pathways presented in Figure . We initially investigated a contribution of each pathway to the total TOF for Pt (111). Assuming the constant deprotonation barrier of 0.3 eV at the equilibrium potential of each electrochemical step , we estimated TOF of each reaction pathway. In the case of T-path, the calculated TOFs of GM mechanisms are much more significant than NN mechanism (Figure ), in agreement with the conclusion of the previous work . This is because the N-N bond formation step in T-path are potential-independent, thus lower activation energies in GM mechanisms led to higher TOF. For example, among GM mechanisms, TOF of GM 1 (NH2* + NH2* → N2H4*, Ga,i = 1.20 eV) was much greater compared to GM 4 (NH* + NH* → N2H2*, Ga,i = 2.69 eV) due to more facile bond formation of the former. For all the other metals, similar trends were observed, indicating that TOF of T-path is determined mainly by the activation energies of N-N bond formation steps (Table ).