Electro-reforming of nylon waste plastic into high-value nitrile over Pt-anchored NiCo2O4 nanowires on nickel foam coupled with green hydrogen production.

Sustainable valorization of waste plastics has emerged as a compelling strategy to mitigate environmental pollution and alleviate global resource depletion. Electrochemical reforming represents a cutting-edge and efficient technology for upgrading waste polyester plastics into valorized organics and renewable energy carriers. However, such an efficient upcycling strategy remains largely underexplored for polyamide waste remediation. Herein, waste nylon 66 was first completely hydrolyzed under strong alkaline conditions to afford two water-soluble monomers, hexamethylenediamine (HMD) and adipate. A low-loading Pt-decorated spinel NiCo2O4 nanowire array grown on nickel foam (Pt-NiCo2O4/NF) was rationally fabricated via a facile integration strategy of hydrothermal growth, calcination treatment, and galvanic replacement. The nucleophilic HMD monomers liberated from nylon hydrolysate were further electrochemically oxidized into high-value adiponitrile at the anode, while green hydrogen was synchronously generated through cathodic water splitting. Compared with the conventional oxygen evolution reaction (OER), HMD oxidation enabled a substantial anodic potential reduction of 295 mV at 100 mA cm-2, highlighting its prominent advantage in lowering overall energy consumption for hydrogen production. The optimized Pt-NiCo2O4/NF electrode achieved a high Faradaic efficiency of 93.9% toward adiponitrile production, together with robust electrolytic durability over 96 h of continuous operation at ampere-level current density. The uniformly dispersed Pt active sites promote the in situ formation of nickel oxyhydroxide species, which are systematically verified as the decisive catalytic centers for HMD electrooxidation. Mechanistic studies reveal that HMD upgrading proceeds via an indirect electrooxidation pathway, with 6-aminohexanenitrile identified as the key reaction intermediate. Preliminary techno-economic evaluation demonstrates that this nylon upcycling system delivers a net economic benefit of 207.83 USD per 100 kg of treated waste nylon 66. This work establishes a feasible and sustainable electrocatalytic strategy for the high-value upcycling of waste polyamides, enabling the coupled production of fine nitrogen-containing chemicals and clean hydrogen energy.