Strengthening the Metal Center of Co–N4 Active Sites in a 1D–2D Heterostructure for Nitrate and Nitrogen Reduction Reaction to Ammonia

Ammonia forms the fundamental agricultural constituent and vital energy provenance of a clean hydrogen mediator. Ammonia production leads to immense energy utilization and drastic environmental repercussion. It is a daunting task to design and synthesize competent catalysts for reduction of nitrogenous species (nitrogen or nitrates, by the nitrogen reduction reaction (NRR) or nitrate reduction reaction (NO3RR) process, respectively) into ammonia. Cobalt­(II) phthalocyanine (CoPc) nanotubes were effectively wrapped by 2D graphene sheets to produce a (1D–2D) heterostructure catalyst, which plays the role of a competent electrocatalyst for the NRR as well as NO3RR. The electrocatalyst showed an ammonia yield rate and a Faradaic efficiency of 58.82 μg h–1 mg–1 cat and 95.12%, respectively, for the NO3RR and for NRR 143.38 μg h–1 mg–1 cat and 43.69%, respectively. Bader charge investigation revealed the transport of charge to Co–N4 active sites from reduced graphene oxide (RGO), which aids during the production of intermediates NNH* for nitrogen reduction and *NOH for nitrate reduction along with suppression of the parasitic HER, thereby demonstrating good selectivity and Faradaic efficiency. This work showcases new mechanistic discernment about the role of work function, interfacial charge transport, and electrocatalytic overpotential for the nitrogen/nitrate reduction reaction.