Hydrophobic Ligand Engineering in Gold Nanoclusters Enables Durable CO2 Electroreduction Via Interfacial Water Control.

Atomically precise metal nanoclusters (metal NCs) provide ideal platforms for probing structure-performance relationship in electrochemical CO2 reduction reaction (eCO2RR). However, how ligand hydrophobicity governs long-term electrode stability at the molecular level remains unsolved. Here, three homonuclear Au22 nanoclusters with ligands of distinct hydrophobicity are used as model systems, and electrostatic potential analysis combined with contact angle measurements correlates ligand structure with the hydrophobicity of NCs. Flow cell tests demonstrate that the strongly hydrophobic Au22 electrode operates stably for 125 h, with lifetimes two and four times longer than those of weakly hydrophobic and near-neutral Au22 electrodes, respectively. Electrode durability shows significantly negative correlation with interfacial water content. In situ ATR-SEIRAS demonstrates that strongly hydrophobic interfaces promote the formation of ordered ice-like hydrogen-bonding networks, which effectively delay interfacial flooding and thereby enhance long-term stability. This work provides molecular-level insight into how hydrophobic ligands simultaneously optimize activity and durability in eCO2RR via interfacial water regulation, offering a general strategy for the design of long-lived CO2 electroreduction catalysts.