Electrocatalytic conversion of waste polyamide-66 hydrolysates into high-added-value adiponitrile and hydrogen fuel

To reduce environmental pollution and plastic recycling costs,poly-amide-66(PA-66)as the most consumed engineering polymer needs to be recycled effectively.However,the existing recycling methods cannot convert waste PA-66 into valuable chemicals for upcycling under ambient conditions.Here,we report an integrated hydrolysis and electrocatalytic process to upcycle waste PA-66 into valuable adiponitrile(ADN),adipic acid,and H_(2) commodities,thereby closing the PA-66 loop.To enable electrooxidation of the PA-66 hydrosylate hexamethylenediamine(HMD),we fabricated anode catalysts with hierarchical Ni_(3)S_(2)@Fe_(2)O_(3) core-shell heterostructures comprising spindle-shaped Ni_(3)S_(2) cores and Fe_(2)O_(3) nanosheet shells.The unique core-shell architecture and synergy of the Ni_(3)S_(2) and Fe_(2)O_(3) catalysts enabled the selective dehydrogenation of C-N bonds from HMD to nitrile C≡N bonds,forming ADN with near-unity Faradaic efficiency at 1.40 V during the 100-h stability test even at 100 mA cm^(−2).X-ray photoelectron spectroscopy revealed that the Ni(Fe)oxy(hydroxide)species formed were in the active state during oxidation,accelerating the activation of the amino C-N bond for dehydrogenation directly into the C≡N bonds.