Boosting Electrocatalytic Ammonia Synthesis via Main-Group Metal Doping and Ionic Liquid Encapsulation in Copper Metal–Organic Frameworks

The electrochemical nitrogen reduction reaction (EN 2 RR) provides a sustainable method for synthesizing ammonia at room temperature, but it is hindered by the low ammonia faradic efficiency (FE) and production yield. Herein, we report an effective EN 2 RR electrocatalyst: the ionic liquid-encapsulated aluminum copper bimetallic metal–organic framework (IL-AlCu-MOF). Comparisons across pristine Cu-MOF, AlCu-MOF, IL-Cu-MOF, and IL-AlCu-MOF reveal that the combination of Al doping and IL encapsulation can simultaneously promote dinitrogen activation and accelerate proton generation via water dissociation in a neutral electrolyte, which synergistically enhances the yield and selectivity of ammonia in EN 2 RR. The IL-AlCu-MOF achieves an NH 3 yield of 124.7 μg·h –1 ·mg cat –1 with an FE NH 3 of 20.3% at −0.3 V (vs reversible hydrogen electrode, RHE) in 0.1 M K 2 SO 4 . In situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) measurements indicate improved water dissociation kinetics over that of IL-AlCu-MOF, and differential electrochemical mass spectrometry (DEMS) captures the EN 2 RR intermediates. Density functional theory (DFT) calculations show that Al doping modulates the Cu electronic structure for enhanced N 2 activation, while IL encapsulation strengthens water adsorption at the MOF surface and thus accelerates water dissociation, both of which contribute to boosting the EN 2 RR performance.