The observed difference in surface hydrophilicity is likely to play a critical role in determining the product selectivity during the CO₂RR, primarily by influencing the proton diffusion and adsorption processes. The hydrophilic nature of the outer surface of Cu₁₁ABT NCs facilitates enhanced proton transport by promoting the proton-jumping mechanism. This efficient proton mobility favors the HER, thereby influencing the competing CO2RR pathway. In contrast, the hydrophobic surface characteristics of Cu11PTT NCs relatively hinder the proton diffusion and adsorption. This deceleration in proton transport dynamics reduces the propensity for HER, thereby shifting the reaction selectivity more significantly toward competing HCOOH formation under a continuous flow of CO2.