Unlocking the Critical Role of Noncovalent Interactions Between Alkali Metal Cations and Nitrate in Promoting the Reduction of Nitrate to Ammonia
Shuai Qi, Xinbao Chen, Huan He, Jiaying Wang, Linli Li, Qihua Huo, Chunyan Shang, Hengpan Yang, Xue Zhang, Qi Hu, Chuanxin He
Abstract
Abstract The electrochemical nitrate reduction reaction (NO 3 − RR) is widely investigated for sustainable ammonia (NH 3 ) production from NO 3 − pollutants. Alkali metal cations (AM + ) in the electrolyte often greatly impact electrocatalytic performance; however, the role of AM + in the NO 3 − RR remains unclear. Here, we first investigate the influence of AM + on the Cu‐catalyzed NO 3 − RR, revealing an activity increase trend of Li + < Cs + < Na + < K + , which is inconsistent with the local electric field and proton transfer rate increase trend of Li + < Na + < K + < Cs + , hinting that the presence of other important factors governs the NO 3 − RR activity. Intriguingly, Ab initio molecular dynamic (AIMD) simulations uncover that Na + , K + , and Cs + with relatively soft solvation shells could be partially desolvated and then coordinate with NO 3 − via a short‐range electrostatic interaction, thereby boosting the rate determining step (RDS), that is the conversion of NO 3 − to NO 2 − . Notably, K + with suitable NO 3 − interaction strength has higher ability to boost the RDS than Na + and Cs + with too weak and strong strength, respectively. Our results highlight that the short‐range electrostatic interaction strength of AM + /NO 3 − is a crucial factor to determine the NO 3 − RR activity.