High Active and Selective Electrocatalytic Nitrate-to-Ammonia Conversion in Fluorine-Rich ZnF<sub>2</sub> Nanorod: Experimental and Theoretical Insight
Jinxiu Zhao, Xuejing Liu, Xiang Ren, Changwen Zhang, Qin Wei, Dan Wu
Abstract
Electrocatalytic reduction of nitrate (NO 3 – ) to highest value-added ammonia (NH 3 ) in a water system is keenly concerning at present. However, the process of NO 3 – to NH 3 is limited by the transfer of eight electrons with various undesired byproducts and the hydrogen evolution reaction (HER). Here, the fluorine-rich ZnF 2 nanorod was experimentally demonstrated and theoretically confirmed as a high active and selective catalyst for electrocatalytic NO 3 – -to-NH 3 conversion. The introduction of fluorine can suppress the most important competition of the HER, thus achieving excellent performance. The NO 3 – conversion, NH 3 selectivity, NH 3 yield rate, and NH 3 Faradaic efficiency can reach 94.93%, 96.46%, 3.901 mg h –1 mg cat. –1, and 96.92%, respectively, as well as a respectable durability. Density functional theory calculations proved that the strong adsorption of NO 3 – species on tetracoordinate Zn atoms can refrain the competitive HER, and the N–O bond of *ONOO would break during the first proton-coupled electron-transfer step to form *OH*ONO occupying the near catalytic site that can reduce the likelihood of nitrogen formation and improve the selectivity of NH 3 .