The negative slope suggests that a more negative ∆𝐺 /0& results in a higher 𝜆 !" ! 44 . This is expected as an appropriate orientation of the proton donor, i.e., water, is required in the proton transfer (PT), and a stronger cation-water interaction would lead to a higher energy penalty in the configurational change of water, i.e., a higher 𝜆 !" ! 44 . The linear correlation between 𝜆 !" ! 44 and ∆𝐺 /0& provides additional support for the claim that water molecules in cations' first hydration shell are the proton donor in the CO2RR. In contrast, the reorganization energies of HER (𝜆 564 ), obtained by fitting H2 partial current density (𝑗 5 ! ) curves (Fig. ), do not exhibit any discernable trend with ∆𝐺 /0& (Fig. ), suggesting that the cation-bound water is unlikely to be the proton source in HER. Instead, the inverse correlation of the 𝜆 564 value with the structural connectivity of H-bond network indicates that a better H-bond connectivity leads to a smaller reorganization energy of HER, which is consistent with the conclusion in the literature . Further, there is a strong linear correlation between 𝐸 * * and 𝜆 !" ! 44 (Fig. ), which stems from the shared origin of the cation-dependence of 𝐸 * * and 𝜆 !" ! 44 on ∆𝐺 /0& .