Alkaline-free oxidation of ethylene glycol into glycolic acid over PdNi/NF in an asymmetric electrolytic cell

Electrocatalytic oxidation of surplus ethylene glycol (EG) to high-value glycolic acid (GA) represents a promising approach for sustainable resource utilization, though critical challenges persist in developing durable electrocatalysts and achieving effective recovery of the free acid product from its salt derivatives in alkaline electrolytes. In this work, a PdNi/NF catalyst was rationally synthesized via a one-step electrodeposition method. Systematic characterization revealed that the electron transfer from Ni to Pd modulates *OH adsorption to accelerate EG oxidation reaction (EGOR) while preventing Pd deactivation through oxidation. The optimized system demonstrated exceptional alkaline performance with a glycolic acid Faraday efficiency of 95% and a current density of 666 mA cm -2 . When implemented in an asymmetric EGOR||HER flow cell configuration where only the cathodic electrolyte contains alkaline, the system demonstrated exceptional operational stability by sustaining 70 mA cm -2 current density at a low cell voltage of 0.9 V in neutral media for over 100 h, with product glycolic acid requiring no further acidification. This investigation provides a practical framework for designing efficient electrocatalytic systems that simplifies product separation steps.