Ambient ammonia synthesis via nitrite electroreduction over NiS2 nanoparticles-decorated TiO2 nanoribbon array

Nitrite (NO2−), as a N-containing pollutant, widely exists in aqueous solution, causing a series of environmental and health problems. Electrocatalytic NO2− reduction is a promising and sustainable strategy to remove NO2−, meanwhile, producing high value-added ammonia (NH3). But the NO2− reduction reaction (NO2−RR) involves complex 6-electron transfer process that requires high-efficiency electrocatalysts to accomplish NO2−-to-NH3 conversion. Herein, we report NiS2 nanoparticles decorated TiO2 nanoribbon array on titanium mesh (NiS2@TiO2/TM) as a fantastic NO2−RR electrocatalyst for ambient NH3 synthesis. When tested in NO2−-containing solution, NiS2@TiO2/TM achieves a satisfactory NH3 yield of 591.9 µmol h−1 cm−2 and a high Faradaic efficiency of 92.1 %. Besides, it shows remarkable stability during 12-h electrolysis test.