To gain deeper insight into the mechanistic pathway, our theoretical approximation reveals that the attachment of antenna-like Cu₃ units to both sides of the overall geometry forms hollow, triangular prism-like sites (Figure ), which are favorable for H adsorption (Eads = -0.89 eV; Figure ). This aligns with the cluster's preference for HER at low overpotentials. Additionally, we identified this site as the active center for CO₂RR also (Figure ), likely due to the extra partial valences of the associated Cu atoms, making them less positively charged or more reduced (Figure ). Additionally, this also corresponds to the most accessible site in the Cu23 NC, exhibiting the least steric hindrance from ligands. While the central Cu atom is the most reduced, it is buried and inaccessible for direct adsorbate interaction. We then investigated the two main CO₂RR pathways on the Cu₂₃ nanocluster, leading separately to HCOOH and CO. As shown in Figure , the hollow triangular prism-like site is active for CO₂RR, with *COOH and *HCOO preferring adsorption at this location (Figure ). The energy profiles (Figure ) suggest that the *HCOO pathway is more favorable, showing stronger intermediate adsorption and a lower limiting potential (0.46 eV from *HCOO to *HCOOH vs. 0.60 eV from *COOH to *CO). The preference for *HCOO over *COOH can be further explained by the carbonyl oxygen atom in HCOO bridging two more reduced Cu atoms (Figure ). This theoretical finding supports the experimental observation that HCOOH is favored as the primary product over CO.