A 3D FeOOH nanotube array: an efficient catalyst for ammonia electrosynthesis by nitrite reduction

Nitrite (NO2-) is a detrimental pollutant widely existing in groundwater sources, threatening public health. Electrocatalytic NO2- reduction settles the demand for removal of NO2- and is also promising for generating ammonia (NH3) at room temperature. A nanotube array directly grown on a current collector not only has a large surface area, but also exhibits improved structural stability and accelerated electron transport. Herein, a self-standing FeOOH nanotube array on carbon cloth (FeOOH NTA/CC) is proposed as a highly active electrocatalyst for NO2--to-NH3 conversion. As a 3D catalyst, the FeOOH NTA/CC is able to attain a surprising faradaic efficiency of 94.7% and a large NH3 yield of 11937 μg h-1 cm-2 in 0.1 M PBS (pH = 7.0) with 0.1 M NO2-. Furthermore, this catalyst also displays excellent durability in cyclic and long-term electrolysis tests.