Ambient ammonia production via electrocatalytic nitrite reduction catalyzed by a CoP nanoarray

Industrial-scale ammonia (NH 3 ) production mainly relies on the energy-intensive and environmentally unfriendly Haber-Bosch process. Such issue can be avoided by electrocatalytic N 2 reduction which however suffers from limited current efficiency and NH 3 yield. Herein, we demonstrate ambient NH 3 production via electrochemical nitrite (NO 2 − ) reduction catalyzed by a CoP nanoarray on titanium mesh (CoP NA/TM). When tested in 0.1 M PBS (pH = 7) containing 500 ppm NO 2 − , such CoP NA/TM is capable of affording a large NH 3 yield of 2,260.7 ± 51.5 µg·h −1 ·cm −2 and a high Faradaic efficiency of 90.0 ± 2.3% at −0.2 V vs. a reversible hydrogen electrode. Density functional theory calculations reveal that the potential-determining step for NO 2 − reduction over CoP (112) is *NO 2 → *NO 2 H.