Recent progress in Pd based electrocatalysts for electrochemical nitrogen reduction to ammonia

Nitrogen reduction into NH3 through electrocatalysis is of paramount importance presently. Because NH3 can be potential clean energy source and primary precursor for nitrogenous compounds. But prevailing method for NH3 synthesis, Haber-Bosch process, is energy inefficient. Electrochemical synthesis can circumvent this hur-dle. Recently, various efforts have been made to synthesize potential electrocatalytic materials for nitrogen reduction reaction (NRR).2 Here in this review, Pd based electrocatalysts for NRR have been critically reviewed and summarized along with the underlying gaps and future perspectives. In first section, different possible mech-anisms for electrocatalytic NRR (EC-NRR)3are discussed. Next section comprises of recent strategies to suppress Hydrogen Evolution Reaction (HER)4 for enhanced EC-NRR and role of electrolyte pH on electrocatalyst's effi-ciency which is followed by section discussing the synthesis methods and their role in determining properties of material. In second last section, all the previously reported Pd catalysts have been classified as monometallic, bimetallic, trimetallic, and discussed systematically in context of NH3 generation and faradaic efficiency. The Pd based electrocatalysts have shown great propensity toward nitrogen reduction reaction but still in its nascent stage. Some strategic improvement in the electrocatalysts design such as use of poor HER support, doping with early transition metals, and sagacious use of electrolyte can push it to new level.

Automated summary

Electrocatalytic reduction of nitrogen into NH3 is currently of paramount importance due to its potential as a clean energy source and primary precursor for nitrogenous compounds. The conventional method for NH3 synthesis, Haber-Bosch process, is energy inefficient, while electrochemical synthesis can overcome this hurdle. In this review, Pd-based electrocatalysts for nitrogen reduction reaction (NRR) are critically reviewed and summarized, along with discussions on possible mechanisms, strategies to suppress Hydrogen Evolution Reaction (HER) for enhanced NRR, and the role of electrolyte pH on electrocatalyst's efficiency. The classification and systematic discussion of previously reported Pd catalysts in the context of NH3 generation and faradaic efficiency are provided, highlighting the potential for further improvement in electrocatalyst design.