High-efficiency electrocatalytic nitrite reduction toward ammonia synthesis on CoP@TiO₂ nanoribbon array

Electrochemical reduction of nitrite (NO₂^-) can satisfy the necessity for NO₂^- contaminant removal and deliver a sustainable pathway for ammonia (NH₃) generation. Its practical application yet requires highly efficient electrocatalysts to boost NH₃ yield and Faradaic efficiency (FE). In this study, CoP nanoparticle-decorated TiO₂ nanoribbon array on Ti plate (CoP@TiO₂/TP) is verified as a high-efficiency electrocatalyst for the selective reduction of NO₂^- to NH₃. When measured in 0.1 M NaOH with NO₂^-, the freestanding CoP@TiO₂/TP electrode delivers a large NH₃ yield of 849.57 μmol h^-1 cm^-2 and a high FE of 97.01% with good stability. Remarkably, the subsequently fabricated Zn-NO₂^- battery achieves a high power density of 1.24 mW cm^-2 while delivering a NH₃ yield of 714.40 μg h^-1 cm^-2.