Electrocatalytic nitrate-to-ammonia conversion on CoO/CuO nanoarrays using Zn-nitrate batteries

Zn-NO 3 − batteries can generate electricity while producing NH 3 in an environmentally friendly manner, making them a very promising device. However, the conversion of NO 3 − to NH 3 involves a proton-assisted 8-electron (8e − ) transfer process with a high kinetic barrier, requiring high-performance catalysts to realize the potential applications of this technology. Herein, we propose a heterostructured CoO/CuO nanoarray electrocatalyst prepared on a copper foam (CoO/CuO-NA/CF) that can electrocatalytically and efficiently convert NO 3 − to NH 3 at low potential and achieves a maximum NH 3 yield of 296.9 μmol h −1 cm −2 and the Faraday efficiency (FE) of 92.9% at the −0.2 V vs. reversible hydrogen electrode (RHE). Impressively, Zn-NO 3 − battery based on the monolithic CoO/CuO-NA/CF electrode delivers a high NH 3 yield of 60.3 μmol h −1 cm −2 , FE NH3 of 82.0%, and a power density of 4.3 mW cm −2 . This study provides a paradigm for heterostructured catalyst preparation for the energy-efficient production of NH 3 and simultaneously generating electrical energy. Heterostructured CoO/CuO nanoarrays on Cu foam (CoO/CuO-NA/CF) were rationally synthesized, and exhibits excellent activity for nitrate reduction reaction. Assembled Zn-NO 3 − battery shows a high-power density of and satisfactory NH 3 yield.