Ultralow-content Pd in-situ incorporation mediated hierarchical defects in corner-etched Cu2O octahedra for enhanced electrocatalytic nitrate reduction to ammonia

Electrochemical reduction of nitrate (NO3-) to ammonia (NH3) offers a sustainable avenue to close the NO3- cycle for NH3 synthesis. Critical to the feasibility of electrochemical NO3--to-NH3 technology is the development of cost-effective, scalable and selective catalysts that can produce NH3 with high yield. To this end, we design and constructure ultralow-content Pd (2.93 at%) in-situ incorporated Cu2O corner-etched octahedra (Pd-Cu2O CEO) with cavity and oxygen vacancy defects for selectively electrochemical NO3--to-NH3 transformation. The unique conner-etched cavity structure, rich surface oxygen vacancies, and Pd-Cu2O dual active sites, synergistically promote nitrate electroreduction undergo ammonia formation reaction pathway. Impressively, the as-made Pd-Cu2O CEO exhibited outstanding activity for electrocatalytic NO3--to-NH3, with high ammonia selectivity (95.31%) and Faradaic efficiency (96.56%). The developed hierarchical-defect strategy may open a new avenue for reasonable design of defect electrocatalysts to contribute desirable properties and functionalities in specific applications.