Enabling electrochemical reduction of nitrogen to ammonia at ambient conditions through rational catalyst designElectronic supplementary information (ESI) available: Total energy of slabs for different facets, free energy diagrams, corrections to the free energies, decomposition potentials, scaling relations and volcano plots as well as summary table are added for Results and discussion section. See DOI: 10.1039/c4cp04838e

Commercial design of a sustainable route for on-site production of ammonia represents a potential economic and environmental breakthrough. In an analogous process to the naturally occurring enzymatic mechanism, synthesis of ammonia could be achieved in an electrochemical cell, in which electricity would be used to reduce atmospheric nitrogen and water into ammonia at ambient conditions. To date, such a process has not been realized due to slow kinetics and low faradaic efficiencies. Although progress has been made in this regard, at present there exists no device that can produce ammonia efficiently from air and water at room temperature and ambient pressure. In this work, a scheme is presented in which electronic structure calculations are used to screen for catalysts that are stable, active and selective towards N 2 electro-reduction to ammonia, while at the same time suppressing the competing H 2 evolution reaction. The scheme is applied to transition metal nitride catalysts. The most promising candidates are the (100) facets of the rocksalt structures of VN and ZrN, which show promise of producing ammonia in high yield at low onset potentials. Investigation of transition metal nitrides reveals extremely promising electrocatalysts for high-yield ammonia production in aqueous electrolytes under ambient conditions.