Accelerating the reaction kinetics from nitrate to ammonia by anion substitution in NiCo-based catalysts

The electrocatalytic nitrate reduction reaction (NITRR) plays a critical role in maintaining global nitrogen balance, which is strongly depended on the reactive activity of catalysts. Herein, we develop a simple hydrothermal technology to replace the O ions in NiCo 2 O 4 (NCO) by S ions to form NiCo 2 S 4 (NCS), in which the bonding interactions among Ni-O or Co-O bonds are stronger than Ni-S and Co-S bonds. Therefore, more 3d electrons can be localized at Ni or Co sites that can donate more charges to the intermediates. As a result, the ammonia yield can be enhanced to 642 μg h −1 cm −2 and the selectivity can reach 92.42%, which is obviously excellent than NCO. This work provides a new insight into accelerating the electrocatalytic activity by regulating the orbital interaction between anions and cations.