Vanadium carbide with periodic anionic vacancies for effective electrocatalytic nitrogen reduction

Abstract

Although electrocatalytic nitrogen reduction reaction (NRR) has been considered as an emerging pathway to produce ammonia (NH3) under ambient conditions owing to its low energy consumption, it still lacks efficient the electrocatalysts to dissociate inert NN bonds. Here, we develop an efficient approach to produce vanadium carbide with abundant periodic carbon vacancies (12.5 at. %) and mesoporous structure as electrocatalysts for NRR via a carbothermic reaction. The typical synthesis protocol involves the use of zinc vanadate decorated vanadium pentoxide nanosheets to homogeneously guide the nucleation and growth of metal organic frameworks (MOFs) on their surface, thus facilitating the in-situ formation of unique vanadium carbide during the subsequent carbothermic reaction. Owing to the optimized substrate-adsorbate binding strength, the intrinsic periodic carbon vacancies of the resultant vanadium carbide could act as coordinatively unsaturated sites to adsorb and activate nitrogen through π-back-donation process, thus promoting the reduction of N2 to NH3. As a consequence, a high yield rate and high Faradaic efficiency with good stabilities are achieved for producing NH3 under ambient conditions.

https://doi.org/10.1016/j.mattod.2020.04.031