Copper-nickel-MOF/nickel foam catalysts grown in situ for efficient electrochemical nitrate reduction to ammonia.

Reducing nitrate (NO) in an aqueous solution to ammonia under ambient conditions can provide a green and sustainable NH-synthesis technology and mitigate global energy and pollution issues. In this work, a CuNi-1,3,5-benzenetricarboxylic acid/nickel foam (CuNi-MOF/NF) catalyst grown in situ was prepared via a one-pot method as an efficient cathode material for electrocatalytic nitrate reduction reaction (NORR). The CuNi-MOF/NF catalyst exhibited excellent electrocatalytic NORR performance at -1.0 V versus a reversible hydrogen electrode, achieving an outstanding faradaic efficiency of 95.88 % and an NH yield of 51.78 mg h cm. The N isotope labeling experiments confirmed that the sole source of N in the electrocatalytic NORR was the NO in the electrolyte. The reaction pathway for the electrocatalytic NORR was derived by in situ Fourier transform infrared spectroscopy and in situ differential electrochemical mass spectrometry. Density functional theory calculations revealed that the Ni element in the CuNi-MOF/NF catalyst had excellent O-H activation ability and strong *H adsorption capacity. These *H species were transferred from the Ni sites to the *NO adsorption intermediates located on the Cu sites, providing a continuous supply of *H to Cu, thereby promoting the formation of *NOH intermediates and enhancing the hydrogenation process of the electrocatalytic NORR.