One-step Upcycling of Palladium from Electroplating Wastewater into Electrocatalysts for Ethylene Glycol Oxidation to Glycolic Acid

Palladium (Pd) is critical for diverse applications, yet its scarcity significantly impedes large-scale application. Recycling from electroplating wastewater offers a viable alternative, but conventional methods suffer from low efficiency and high-energy consumption. Herein, we present a ternary NiCoMn layered double hydroxide (NiCoMn-LDH) that enables spontaneous in situ anchoring of Pd nanoparticles from Pd-containing electroplating wastewater, achieving an efficient electrocatalyst (Pd/NiCoMn-LDH) for electrooxidation of ethylene glycol (EG) to glycolic acid (GA). Specifically, NiCoMn-LDH exhibits an exceptional Pd recovery capacity of 800.95 mg/g and fast capture kinetics, achieving 98.9% removal within 10 min for the simulated Pd-containing wastewater. In natural Pd-containing electroplating wastewater, it effectively reduces the Pd2+ concentration from 319.3 to 18.6 mg/L, demonstrating a superior Pd-scavenging efficiency. Furthermore, benefiting from the synergistic effect of metal–support, the resulting Pd/NiCoMn-LDH (with a Pd loading of 8.5 wt %) delivers well electrocatalytic performance toward ethylene glycol electrooxidation, achieving a current density of 297.5 mA cm–2 at 0.95 V vs RHE, along with high GA selectivity (92.6%) and good stability. Notably, when authentic Pd-containing electroplating wastewater is used as the Pd source, the as-prepared catalyst maintains a comparable performance, with a current density of 235.9 mA/cm–2 and a GA selectivity of 91%. This work establishes a sustainable route for upcycling metal-bearing waste into high-performance functional materials, contributing to a circular economy.