A New Composite Lead Electrode for the Reduction Synthesis of Adiponitrile from Acrylonitrile

Adiponitrile (ADN) serves as a critical intermediate for manufacturing polyamide 66. Electrochemical hydrodimerization of acrylonitrile (AN) offers a green and sustainable route for ADN production, yet conventional lead plate cathodes still suffer from high cell voltage, insufficient mechanical stability, and lead dust shedding during long-term operation. In this work, we developed a novel composite lead electrode in ambient air to overcome these drawbacks. Key preparation parameters, including calcination temperature, polytetrafluoroethylene (PTFE) content, substrate type, dispersion method, and dispersant dosage, were carefully screened and optimized. The optimal conditions were determined as follows: PTFE mesh as the substrate, 10% PTFE relative to lead powder, mechanical stirring dispersion, 0.5 wt% sodium hexametaphosphate as dispersant, air calcination at 325 °C, and subsequent electrochemical reduction. SEM, XRD, and XPS characterizations showed that the optimized electrode features a three-dimensional porous network assembled from interlaced rod-like and flower-like micro/nanostructures, which greatly elevates the specific surface area, enriches active sites, and facilitates electrolyte penetration and mass transport. After electrochemical reduction, the electrode surface was dominated by catalytically active Pb0. Electrochemical tests indicated that the composite electrode delivered a current density of 60–70 mA·cm−2 at −1.6 to −2.0 V (vs. SCE) for AN reduction, nearly three times higher than that of a conventional lead plate. In addition, the composite electrode showed improved mechanical hardness and completely suppressed lead dust shedding, greatly enhancing operational safety and service life. Stable voltage was maintained during long-term electrolysis. This study provides a low-cost and scalable strategy for fabricating high-performance lead-based composite cathodes, which can support the industrial-scale green electrosynthesis of adiponitrile from acrylonitrile.