To calculate free energies of electrochemical deprotonation steps, we employed the computational hydrogen electrode (CHE) method, which assumes that the chemical potential of proton and electron pair (H + + e -) is equal to that of 0.5 H2(g) at standard conditions and U = 0 VRHE . DFT calculated electronic energies were converted into free energies by adding free energy corrections, i.e., 𝐺 = 𝐸 𝐷𝐹𝑇 + 𝑍𝑃𝐸 + ∫ 𝐶 𝑝 𝑑𝑇 -𝑇𝑆 , where 𝐸 𝐷𝐹𝑇 is DFT calculated total energy, and 𝑍𝑃𝐸 , ∫ 𝐶 𝑝 𝑑𝑇 , and 𝑇𝑆 correspond to zero-point energy, enthalpic, and entropic corrections, respectively. These corrections were calculated using the ideal gas (harmonic) approximation for gas molecules (adsorbates) implemented in Atomic Simulation Environment (ASE) (Table ). An implicit solvation effect was included using VASPsol . We calculated binding free energies of adsorbates with respect to H2 and NH3 molecules (Supplementary Note 1)