2D copper metal-organic framework as an electrocatalyst for the highly efficient electrochemical reduction of low concentration nitrate/nitrite-to-ammonia

The accumulation of nitrate/nitrite (NO x – ) in wastewater poses a threat on ecological safety. Electrocatalytic NO x – reduction to ammonia (NO x – RR) is feasible to realize green ammonia production. This work developed a 2D copper metal-organic framework of Cu-BDC (H 2 BDC = 1,4-benzene dicarboxylic acid) as an efficient electrocatalyst for NO x – RR, exhibiting high-performance with the NH 3 yield of 71.20 μmol‧h −1 ‧cm −2 and a Faraday efficiency of 80.9 % at −0.746 V ( vs. RHE) for NO 2 − RR, and the NH 3 yield of 130.16 μmol‧h −1 ‧cm −2 and a Faraday efficiency of 67.42 % at −0.946 V ( vs. RHE) for NO 3 − RR. Isotope labelled 14 NO 3 − and 15 NO 3 − produced 14 NH 4 + and 15 NH 4 + , supporting the formation of NH 3 comes from the NO 3 − RR. In three NO x – RR cycles, all NH 3 yields and Faraday efficiencies show a slight change, demonstrating an excellent electrocatalytic stability in NO x – RR. Our work provides a new material platform for the elimination of nitrate and nitrite through electrocatalytic reduction.