Surface charge density and hydration free energy are identified as the key descriptors with which alkali metal and organic cations impact the overall reaction rate in terms of both electronic and vibrational couplings. Water molecules in the first hydration shell of cations are likely the proton source in the CO2RR, while water unassociated with cations serves as the proton source for the HER. The method developed in this work is generally applicable for analyzing the key factors in affecting nonadiabatic PCET processes. was conducted automatically by the potentiostat (90% compensation of the uncompensated resistance, Ru). The disk was scanned from 0 to -1.0 V at 50 mV s -1 to conduct CO2RR with the rotation rates of 3000 rpm. The ring electrode potential was set to 1.0 V to quantify the amount of formed CO. At this potential, there is no kinetic limitation for CO oxidation , which supported by the Koutechy-Levich analysis of the CO oxidation rates in 0.1 M NaHCO3 at 1.0 V (Fig. ).