Ampere-Level Pulsed Electrosynthesis of Glycolic Acid over Pd-Modified Low-Coordination Cobalt Nanosheets

Abstract Selective electrosynthesis of glycolic acid (GA) from ethylene glycol (EG) offers an attractive route for producing value-added chemicals, yet achieving high performance at ampere-level current densities remains challenging because of the oxidative deactivation of noble-metal active sites. Herein, we report a Pd nanoparticle-decorated low-coordination Co nanosheet catalyst (Pd@L-Co) for efficient pulsed electrosynthesis of GA. Benefiting from the strong electronic interaction between Pd nanoparticles and defect-rich Co nanosheets, the optimal Pd@L-Co catalyst delivers ampere-level EG oxidation with a maximum GA Faradaic efficiency of 96.96% at 0.9 V vs RHE and a GA yield of 2.42 mmol h–1 cm–2 at 1.3 V vs RHE. More importantly, pulse electrolysis effectively suppresses the continuous oxidation of Pd sites, maintaining highly active metallic Pd species and enabling sustained catalytic performance. Operando measurements reveal that alternating anodic/cathodic potentials dynamically regenerate Pd active centers while simultaneously preventing the accumulation of surface-poisoning intermediates. Density functional theory calculations further demonstrate that defect-rich Co optimizes the electronic structure of Pd, promotes OH* activation, and lowers the energy barrier to the rate-determining step of intermediate formation.