Ionic-liquid-induced phthalocyanine monolayer electrocatalyst for efficient nitrogen reduction reaction

The electrochemical NRR, which can be driven by renewable energy sources, is an emerging strategy for addressing the high energy consumption and CO2 emission issues caused by the traditional Haber–Bosch ammonia synthesis technique. FePc catalyzes the electrochemical ammonia synthesis reaction well, but intermolecular π-stacking and multi-layer overlapping lead to low NH3 yields. Here, [Bmim][Cl] and [Bmim][NTF2] ILs were used to induce monolayer dispersion of FePc. Ionic-liquid-induced FePc electrocatalyst, namely FePc/C-700, which was constructed with ILs as the carbon source, gave an excellent NH3 yield (24.25 μg mgcat−1 h−1) and Faradaic efficiency (30.59%) at − 0.1 V. The formation of a monolayer FePc structure was confirmed by HAADF-STEM and XANES. The results of DFT calculations and NRR experiments showed that the monolayer FePc structure promoted N2 adsorption and inhibited the competitive HER. These results will be useful in the design of active sites of layered macromolecules to achieve efficient electrochemical NRR.