Molecular Electrocatalysis Coupled With a Palladium Membrane Reactor Affords Selective Nitrogen Reduction.

Ammonia production is a cornerstone of modern industry and society, yet the conventional Haber-Bosch process accounts for nearly 2% of the global CO2 emissions. A promising and potentially greener alternative is electrochemical ammonia synthesis, though effective systems in this context are largely lacking. To this end, this study develops a reactor platform that integrates a palladium membrane reactor as a hydrogen conduit coupled with a mono-terpyridine nickel molecular catalyst. This system achieved a peak Faradaic efficiency of 36% for ammonia production at a current density of -0.85 mA cm-2 in a decoupled electrocatalytic manner. In situ spectroscopic analysis, electroanalytical techniques, and computational modelling have revealed a unique catalyst mechanism that entails the formation of a Ni-H species generated from the active hydrogen from the Pd membrane as a key intermediate in the reaction route. The insights gained from this unique system stand to aid the development of practical ammonia production systems while expanding the community's knowledge base on dinitrogen activation.