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 hurdle. 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 mechanisms 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 efficiency 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.