Atomic defects in pothole-rich two-dimensional copper nanoplates triggering enhanced electrocatalytic selective nitrate-to-ammonia transformation

The development of efficient catalysts for electrocatalytic selective conversion of nitrate pollutants into valuable ammonia is a project of far-reaching importance. This work demonstrated the in situ electroreduction of pre-synthesized CuO nanoplates into defect-rich metallic Cu nanoplates and evaluated their electrocatalytic nitrate-to-ammonia activity. Concentrated atomic defects in the as-converted Cu nanoplates could favor the adsorption, enrichment and confinement of nitrate ions and pivotal reaction intermediates, selectively promoting eight-electron reduction (NH3 formation). Consequently, the resultant defect-rich Cu nanoplates exhibit a significant ammonia production rate of 781.25 μg h−1 mg−1, together with excellent nitrate conversion (93.26%), high ammonia selectivity (81.99%) and good electrocatalytic stability, superior to the defect-free Cu nanoplate counterpart. Isotope labelling experiments demonstrated that the source of ammonia was from nitrate. Both 1H NMR and colorimetric methods were used to quantify the ammonia yield.