Geometrically Ordered and High-Density Dual Active Sites Efficiently Promote the Electrosynthesis of a Nylon-6 Precursor with Ampere-Level Current

Abstract Electrosynthesis of cyclohexanone oxime, the vital precursor for producing nylon-6, through C−N coupling reaction from cyclohexanone and nitrate serves as an environmentally friendly route to substitute for conventional technology. However, an electrocatalyst with a single active site is not sufficient to realize the co-adsorption and co-activation of various reactants, which is not conducive to the C−N coupling processes, resulting in the unsatisfactory selectivity and Faraday efficiency of cyclohexanone oxime. Here, we present a geometrically ordered PdCu (O-PdCu) catalyst with high-density dual active sites to efficiently synthesize cyclohexanone oxime via co-reduction of cyclohexanone and nitrate. Operando measurements and control experiments reveal that O-PdCu can generate more NH2OH intermediates to react with cyclohexanone, and the geometric structure with highly ordered and high-density Pd-Cu dual active sites is more favorable to the C−N coupling process, thereby enhancing the performance of cyclohexanone oxime electrosynthesis. Consequently, the O-PdCu achieves selectivity in organic products and Faradaic efficiency of 100% and 70.75% at −0.4 V vs RHE, respectively. Furthermore, the O-PdCu catalyst facilitates the production of 2.20 g of cyclohexanone oxime with a yield rate of 4.82 mmol cm−2 h−1 at a current of 1.12 A through a large-scale synthesis process. Technoeconomic analysis further indicates that the electrosynthesis of cyclohexanone oxime in our system represents a feasible and economically profitable strategy.