Ambient One‐Pot Electrocatalytic Synthesis of Caprolactam From Cyclohexanone and Nitrate Over Ag‐Ag ₄ Sn‐SnO ₂ Nanoparticles

Caprolactam (CPL), a monomer of nylon-6 widely used in automotive, machinery, and electronics, is traditionally synthesized from cyclohexanone (CYC) through a complex process that generates low-value ammonium sulfate, leading to environmental pollution. In contrast, electrochemical methods offer a safer, greener one-pot synthesis of CPL from waste NO₃ ⁻, but currently, the coupling of CYC and NO₃ ⁻ primarily produces cyclohexanone oxime (CHO), and the direct generation of CPL is challenging. Here, we report for the first time the electrochemical conversion of CYC and NO₃ ⁻ to high-value CPL in a one-pot process under ambient conditions. Using Ag-Ag₄Sn-SnO₂ nanoparticle catalysts, we achieved a remarkable 96% yield and 97% selectivity for CPL electrosynthesis. In situ characterizations, control experiments, and theoretical calculations suggested the importance of balanced activation of NO₃ ⁻ and CYC substrates on the Ag-Ag₄Sn-SnO₂ catalysts for achieving high-efficient CPL electrosynthesis. The method also exhibits broad versatility in synthesizing various amide compounds, including paracetamol for antipyretic. Notably, scaling up the reactor enabled a high CPL production rate of 3.41 g h⁻¹ gcat ⁻¹ with a 90.5% isolated yield, highlighting the potential of this technique for large-scale electrosynthesis.