Tuning the Selectivity for High Yield Ammonia Production in Electrochemical Nitrate Reduction using Sulfur and Nitrogen‐Rich Carbon Catalyst

Abstract The electrocatalytic nitrate (NO 3 − ) reduction reaction (NO 3 RR) offers a promising pathway for synthesizing value‐added ammonia (NH 3 ) while removing NO 3 − pollutants. However, this reaction is hindered by NO 3 − adsorption and slow kinetics involving multiple proton and electron transfer steps. In pursuit of an efficient catalyst, a sulfur and nitrogen‐rich carbon catalyst, SNC 700, with a cuboidal morphology is presented for selective electrochemical NO 3 − reduction to NH 3 . The SNC 700 catalyst exhibited a higher NH 3 Faradaic efficiency (F.E.) of 97.83% and an extremely low F.E. of nitrite (NO 2 − , ≈ 0.69%) compared to the counterpart NC 700 catalyst (F.E. NH3 42.85%, F.E. NO2‐ 9.92%) at a potential of −0.6 V vs. RHE. Complementary insights from in‐situ Raman spectroscopy and microelectrochemical studies revealed the reaction pathway, highlighting a rapid reduction of NO 3 − intermediate and more favorable hydrogenation over SNC 700 catalyst compared to NC 700. This suggests that incorporating sulfur into the nitrogen‐containing carbon structure enhances hydrogen adsorption, leading to improved NO 3 − to NH 3 selectivity. This work presents a straightforward and practical approach to address the challenges of limited NO 3 − reduction selectivity, particularly for carbon‐based materials.