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

Abstract

AbstractTo reduce environmental pollution and plastic recycling costs, polyamide‐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 H2 commodities, thereby closing the PA‐66 loop. To enable electrooxidation of the PA‐66 hydrosylate hexamethylenediamine (HMD), we fabricated anode catalysts with hierarchical Ni3S2@Fe2O3 core‐shell heterostructures comprising spindle‐shaped Ni3S2 cores and Fe2O3 nanosheet shells. The unique core‐shell architecture and synergy of the Ni3S2 and Fe2O3 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.