Eight electron nitrate (NO3–) reduction to ammonia (NH3) offers a cost–effective and energy efficient route than the Haber–Bosch process. The state of art electrocatalysts for nitrate reduction shows potential activity, albeit suffering from poor Faradaic efficiency, kinetically sluggish multi electron–proton process, and competitive hydrogen evolution reaction. Herein, we present a hollow iron phthalocyanine (FePc) rectangular nanotube (RNTs) electrocatalyst with 100 % Faradaic efficiency and 35067.09 µg h–1 mgcat–1 ammonia yield, which is 3.5 times higher than that of FePc nanorods. One-of-a-kind hollow nanostructure has Fe-N4 active motif sites necessary for NO3– activation, dissociation, specific intermediate formation, and interaction, resulting in the energy-efficient generation of NH3, according to in-situ research combined with theoretical analysis of molecular scale reaction mechanism. These unique results, coupled with the monitoring of pH changes in real time during electrolysis, open up new possibilities for progressive ammonia production with reduced carbon footprint.