Amorphous CoB nanoarray as a high-efficiency electrocatalyst for nitrite reduction to ammonia

Electrochemical reduction of nitrite (NO₂⁻) is considered as an eco-friendly and sustainable strategy for simultaneous NH₃ production and NO₂⁻ removal. However, electroreduction of NO₂⁻ is a complex reaction involving multi-electron transfer steps, thus requiring highly selective and active electrocatalysts. Herein, we report that amorphous CoB supported on TiO₂ nanoarray acts as an efficient catalyst for NH₃ synthesis via electrochemical NO₂⁻ reduction. In 0.1 M Na₂SO₄ with 400 ppm NO₂⁻, such an electrocatalyst achieves an outstanding yield of 233.1 μmol h⁻¹ cm⁻² and a high faradaic efficiency of 95.2% at −0.7 V. In addition, its performance remains stable during long-term electrolysis and cycling tests.