Efficient Electrosynthesis of Dinitrile from Nylon-66-Derived Diamine Enabled by Highly Active Mn-O-Co Motifs in Spinel Oxides.

Conventional industrial production of adiponitrile (ADN), a critical building block in energy storage devices and polymer manufacturing, is predominately achieved via butadiene hydrocyanation. However, this method suffers from harsh energy demand and reliance on highly toxic hydrogen cyanide, thereby posing significant environmental and safety concerns. Herein, we developed a sustainable electroreforming strategy for ADN synthesis from waste nylon-66 using Mn doped Co3O4 (Mn-Co3O4) catalyst. Mn doping strategy endows Co3O4 with enhanced activity toward electrooxidation of nylon-66-derived hexamethylenediamine (HMD). Combined experimental and theoretical investigations reveal that the selective incorporation of Mn into octahedral Co3+ sites creates highly active Mn-O-Co motifs, which concurrently enables HMD adsorption at Mn sites and the formation of reactive hydroxyl species at Co sites. Such a synergistic interaction between Mn and Co sites promotes N─H bond activation, enabling Mn-Co3O4 to achieve a high Faradaic efficiency of ADN (93%) at 200 mA cm-2, with a yield rate of 0.87 mmol cm-2 h-1. Furthermore, our study demonstrates a scalable route to generate high-purity ADN from end-of-life cable ties through acidic hydrolysis treatment followed by two-electrode electrolysis, achieving an overall yield of 95%. This work offers a sustainable approach for ADN electrosynthesis from waste plastics leveraging renewable electricity.