Aryl sulfur ligand-modulated silver catalysts with tailored binding affinity for selective nitrate-to-ammonia conversion
Longcheng Zhang, Yuan Liu, Ling Li, Xiaoning Li, Pengfei Song, Ting Chen, Qian Wu, Justin Zhu Yeow Seow, Kai Tang, Shirong Sun, Xia Guo, Zhichuan Xu
Abstract
Manipulating the selectivity-determining step in the hydrogenation of nitrogen-containing intermediates is critical to achieving high ammonia selectivity in electrocatalytic nitrate reduction. Here, we propose a molecular interface engineering strategy that functionalized with thiol-anchored aromatic ligands to regulate the interfacial binding affinity and activation of key nitrogen-containing intermediates on silver nanocube surfaces. By systematically varying the electronic properties of the substituents, we identify 4-(methylthio)benzaldehyde as the most effective ligand, increasing the ammonia Faradaic efficiency from 50.8% to 98.9% and achieving a yield rate of 14,366.1 μg h–1 cmgeo–2 at –0.63 V versus reversible hydrogen electrode. In situ electrochemical characterizations combined with theoretical simulations further reveal that 4-(methylthio)benzaldehyde modification promotes the activation of weakly hydrogen-bonded water molecules and accelerates the hydrogenation of *HNO intermediates. This targeted modulation of interfacial binding affinity offers an effective strategy for selectivity control in electrocatalytic nitrate reduction. The enhanced performance is further validated in a membrane electrode assembly electrolyser, underscoring the practical viability of this molecular design strategy for selective nitrate conversion. Controlling reaction selectivity in complex multistep electrochemical transformations remains a major challenge. Here, the authors report that molecular interface engineering on silver electrodes enables precise regulation of key reaction intermediates for efficient ammonia electrosynthesis.