Communication—Electrochemical Reduction of N2 to Ammonia by Vanadium Oxide Thin Films at Neutral pH: Oxophilicity and the NRR Reaction

Abstract

Electroreduction of N2 to NH3 is an energy- and environmentally-friendly alternative to the Haber-Bosch process. Little is known, however, about reactive sites for electrochemical nitrogen reduction reaction (NRR) at Earth-abundant oxide or oxynitride surfaces. Here, we report N-free VIII/IV-oxide films, created by O2 plasma oxidation of polycrystalline vanadium, exhibiting N2 reduction at neutral pH with an onset potential of −0.16 V vs Ag/AgCl. DFT calculations indicate that N2 scission from O-supported V-centers is energetically favorable by ∼18 kcal mol−1 compared to N-supported sites. Theory and experiment yield fundamental insights concerning the effect of metal oxophilicity towards design of earth-abundant NRR electrocatalysts.