(666d) Mechanistic Insights into Electrochemical Nitrogen Reduction Reaction on Vanadium Nitride Nanoparticles

Renewable production of ammonia, a building block for most fertilizers, via the electrochemical nitrogen reduction reaction (ENRR) is desirable; however, a selective electrocatalyst is lacking. Here we show that vanadium nitride (VN) nanoparticles are active, selective, and stable ENRR catalysts. ENRR with ¹⁵N₂ as the feed produces both ¹⁴NH₃ and ¹⁵NH₃, which indicates that the reaction follows a Mars–van Krevelen mechanism. Ex situ and operando characterizations indicate that VN_0.7O_0.45 is the active phase for ENRR and the conversion of VN_0.7O_0.45 to the VN phase leads to catalyst deactivation. Quantitative isotopic labeling results identify the amounts of two different types of active sites: 1) be stable at steady state and 2) deactivate during ENRR. The key kinetic parameters of ENRR have also be investigated.