Electrochemical nitrite (NO₂ ⁻) reduction to ammonia (NH₃) can not only remove harmful NO₂ ⁻ in wastewater, but also produce valuable NH₃. Herein, a CoFe nanoalloy encapsulated in nitrogen-doped carbon (CoFe-NC) electrocatalyst was fabricated for nitrite reduction, which achieved a high NH₃ Faraday efficiency of 94.5%, and a large NH₃ yield of 4050.6 μg h⁻¹ cm⁻² in a neutral electrolyte.