Exceptional Electroreduction of Nitrate to Ammonia Promoted by Concerted Electron–Proton Transfer in Cu-Decorated <i>MFI</i> Zeolites

The concerted electron-proton transfer (CEPT) can substantially enhance the microkinetics of electrocatalysis by circumventing the formation of high-energy intermediates. Herein, we report the decoration of the <i>MFI</i> zeolite matrix with isolated Cu(II) sites in the proximity of intrinsic Brønsted acid sites (BASs), promoting the CEPT synergy in electrocatalysis. By modulating the spatial arrangement of "Cu-BAS" pairs in Cu-Z(23) zeolite, we show a Faradaic efficiency of 98% for electroreduction of nitrate to ammonia, achieving an exceptional yield of 103.1 mg h^-1 cm^-2 at a current density of 1.3 A cm^-2. Cu-Z(23) also exhibits an excellent activity at low concentrations of nitrate (e.g., 50 ppm) and a high catalytic stability of 50 h. Synchrotron X-ray powder diffraction, solid-state nuclear magnetic resonance spectroscopy, and modeling studies reveal the critical role of the proximate "Cu-BAS" pairs in facilitating the CEPT process. This approach uncovers the overlooked capability of "electrical insulating" zeolites as effective electrocatalysts to drive future sustainable chemical synthesis.