Octahedral CoS2 electrocatalysts for efficient nitrate reduction to ammonia

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.