Interfacial Proton Ordering Near the Electrode Surface Directs Carbonyl Electroreduction to Methylene

Carbonyl-to-methylene deoxygenation is a fundamental transformation in organic synthesis, but conventional Clemmensen and Wolff-Kishner-Huang reductions require harsh acidic or basic conditions. Electrochemical reduction offers a milder alternative, yet commonly stops at the alcohol stage because the initially formed alcohol intermediate desorbs from the electrode before further C─O bond activation. Here, we report a ${\mathrm{Pd}}_{97}{\mathrm{Ni}}_3$ -Gly interfacial catalytic system for aqueous electrochemical carbonyl-to-methylene conversion. In this system, the Pd-rich ${\mathrm{Pd}}_{97}{\mathrm{Ni}}_3$ electrode and glycine-mediated interfacial regulation cooperate to retain alcohol intermediates at the electrified interface and promote their subsequent deoxygenation to methylene products. Time-dependent reaction analysis supports a stepwise pathway involving initial carbonyl hydrogenation to an alcohol intermediate followed by further deoxygenation. Mechanistic and structural studies suggest that Pd sites supply surface H*, electron-deficient Ni-related sites generated through Ni─Pd coordination assist alcohol-intermediate retention, and glycine regulates local proton availability and H* coverage in the interfacial region. This work highlights the ${\mathrm{Pd}}_{97}{\mathrm{Ni}}_3$ -Gly system as an effective interfacial platform for directing carbonyl electroreduction beyond the alcohol endpoint under mild aqueous conditions.