Octahedral CoS2 electrocatalysts for efficient nitrate reduction to ammonia

Abstract

Electroreduction of nitrate (NO₃⁻) has emerged as a promising strategy for producing ammonia (NH₃) at room temperature in recent years; however, the formation of NO₂⁻ intermediate byproduct seriously limits the conversion efficiency of NO₃⁻ to NH₃. In this study, we identify that octahedral CoS₂ (CoS₂ OC) can effectively convert NO₃⁻ to NH₃ with a high performance (NH₃ yield rate: 10.6 ± 0.4 mg h⁻¹ cm⁻², faradaic efficiency: 96 ± 1.5%). Density functional theory (DFT) calculations coupled with multiple in situ (spectro)electrochemical experiments reveal that CoS₂ (111) with high electron supply capacity facilitates reduction of NO₂⁻ to NH₃, thus enhancing NO₃RR activity. Overall, our study provides an efficient electrocatalyst to avoid the accumulation of NO₂⁻ intermediate byproduct to facilitate the conversion of NO₃⁻ to NH₃, paving the way towards achieving green ammonia production using a more convenient approach.