54b. The decreasing binding energy with increasing cathodic overpotential accelerates the rate of formation of hydrogen molecules in the Tafel step. The main specific property is the value of the molecular hydrogen induced H-upd peaks shift. Here we use a rather low forward rate constant of the Tafel step and of the Volmer step to obtain the experimentally observed value of around 50 mV. This means that the H2 limiting current of the HOR is not reached. As we have simulated the HOR/HER only for one binding site, this phenomenon may be resolved by employing a distribution of sites with different binding energies. These binding sites would contribute differently to the observed steady-state HOR current and the pseudocapacitive current response, while maintaining the general properties of the simulated site, including the value of the micropolarization exchange current density and HER Tafel slope. In this context, we object the idea that hydrogen atoms from equivalent binding sites would combine to form a hydrogen molecule, as would be implied by Eqs. 54a-b: Equivalent binding sites are at least 0.707 lattice constants apart on fccmetals (for platinum: 0.707 x 392 pm = 274 pm) whereas the hydrogen molecule bond length is less than 73 pm. Instead, as illustrated in Fig. , we think that hydrogen from closer, but energetically different bindings sites combine to form molecular hydrogen. Preliminary investigations of such paths suggest that the general properties of the proposed mechanism are conserved, while the meaning of associated rate constants and formal potentials becomes more complex, beyond the scope of this work.