ITO@TiO2 nanoarray: An efficient and robust nitrite reduction reaction electrocatalyst toward NH3 production under ambient conditions

Abstract

Ambient electrochemical nitrite (NO2-) reduction is viewed as an effective and sustainable approach for simultaneously removing NO2- and producing ammonia (NH3). However, the complex multi-electron transfer steps involved in the NO2- reduction reaction (NO2-RR) lead to sluggish kinetics and low product selectivity toward NH3, underscoring the need for NH3 synthesis electrocatalysts with high activity and durability. Herein, we report amorphous indium–tin oxide sputtered on a TiO2 nanobelt array on a Ti plate (ITO@TiO2/TP) as a 3D NH3-producing catalyst for the NO2-. In 0.5 ​M LiClO4 with 0.1 ​M NO2-, it shows greatly boosted NO2-RR activity toward NH3 production, with excellent selectivity, achieving a large NH3 yield of 411.3 ​μmol ​h−1 ​cm−2 and a high Faradaic efficiency of 82.6%. It also shows high durability for continuous electrolysis. A Zn‐NO2- battery with ITO@TiO2/TP cathode offers an NH3 yield of 23.1 ​μmol ​h−1 ​cm−2 and a peak power density of 1.22 ​mW ​cm−2.