Reversed I1Cu4 single- atom sites for superior neutral ammonia electrosynthesis with nitrate

• 成果类型: Article
• 署名作者: Zhou, Bing; Tong, Yawen; Yao, Yancai; Zhang, Weixing; Zhan, Guangming; Zheng, Qian; Hou, Wei; Gu, Xiang - Kui; Zhang, Lizhi
• 署名单位: Central China Normal University; Shanghai Jiao Tong University; Wuhan University
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-12558
• DOI: 10.1073/pnas.2405236121
• 发表日期: 2024-09-10
• 关键词: reduction; diffraction; mechanism; proton; water

摘要

Electrochemical ammonia (NH3) synthesis from nitrate reduction (NITRR) offers an appealing solution for addressing environmental concerns and the energy crisis. However, most of the developed electrocatalysts reduce NO3- to NH3 via a hydrogen (H*)- mediated reduction mechanism, which suffers from undesired H*- H* dimerization to H2, resulting in unsatisfactory NH3 yields. Herein, we demonstrate that reversed I1Cu4 single- atom sites, prepared by anchoring iodine single atoms on the Cu surface, realized superior NITRR with a superior ammonia yield rate of 4.36 mg h -1 cm-2 and a Faradaic efficiency of 98.5% under neutral conditions via a proton- coupled electron transfer (PCET) mechanism, far beyond those of traditional Cu sites (NH3 yield rate of 0.082 mg h -1 cm-2 and Faradaic efficiency of 36.5%) and most of H*- mediated NITRR electrocatalysts. Theoretical calculations revealed that I single atoms can regulate the local electronic structures of adjacent Cu sites in favor of stronger O- end- bidentate NO3 - adsorption with dual electron transfer channels and suppress the H* formation from the H2O dissociation, thus switching the NITRR mechanism from H*- mediated reduction to PCET. By integrating the monolithic I1Cu4 single- atom electrode into a flow- through device for continuous NITRR and in situ ammonia recovery, an industrial- level current density of 1 A cm-2 was achieved along with a NH3 yield rate of 69.4 mg h -1 cm-2. This study offers reversed single- atom sites for electrochemical ammonia synthesis with nitrate wastewater and sheds light on the importance of switching catalytic mechanisms in improving the performance of electrochemical reactions.