Self-Assembly of Dual-Metal-Substituted Polyoxometalates into Two-Dimensional Superstructures for Highly Selective Electrocatalytic Imine Synthesis

The development of efficient and sustainable strategies for imine synthesis remains highly desirable, as conventional approaches often suffer from harsh reaction conditions and limited selectivity. Herein, we report an electrocatalytic strategy that utilizes reproducible electricity to drive the selective oxidative coupling of benzylamine (BA) into imines under mild conditions. A series of disubstituted Keggin polyoxometalates (POMs), M2PW10O38 (M = Fe-Zn), were assembled at the gas-liquid interface into well-defined two-dimensional nanosheet superstructures. Structural characterizations reveal a uniform nanosheet morphology, featuring single-cluster assembly and highly ordered arrangements of POM units. Among these, the Fe2PW10 NS exhibits outstanding electrocatalytic performance for BA oxidation, achieving >99% conversion, 99% yield of the target imine, and a Faradaic efficiency of 81.8%, along with excellent cycling stability. Comparative studies highlight the advantages of the cluster-assembled superstructure arising from the high density of accessible active sites and the synergistic effects of the ordered superstructure. Furthermore, substrate scope investigations demonstrate the broad applicability toward diverse amine substrates. This work provides a viable platform for the green and efficient synthesis of value-added imines and offers valuable insights into the design of advanced POM-based electrocatalysts.