Oxygen vacancies in Co3O4 nanoarrays promote nitrate electroreduction for ammonia synthesis

Nitrate (NO3-) electroreduction has emerged as an attractive strategy for ammonia (NH3) synthesis at room temperature but lacks efficient electrocatalysts with high selectivity for NH3 formation. In this work, we report that an oxygen vacancy-enriched Co3O4 nanosheet array on carbon cloth (CC) behaves as a highly active and stable catalyst for NO3- reduction to NH3. In 0.1 M NaOH with 0.1 M NO3-, this electrocatalyst shows a large NH3 yield of 12 157 mu g h(-1) cm(-2) and a FE of up to 96.9% at -0.5 V, considerably outperforming its pristine Co3O4/CC counterpart (4930 mu g h(-1) cm(-2); 56.9%). Moreover, it achieves high stability during long-term electrolysis, and its application in nitrate-containing wastewater was also tested.