Engineering Spin States of Isolated Copper Species in a Metal-Organic Framework Improves Urea Electrosynthesis  

作　　者：Yuhang Gao Jingnan Wang Yijun Yang Jian Wang Chuang Zhang Xi Wang Jiannian Yao 

机构地区：[1]Key Laboratory of Photochemistry,Beijing National Laboratory for Molecular Sciences,Institute of Chemistry,Chinese Academy of Sciences,Beijing 100190,People’s Republic of China [2]University of Chinese Academy of Sciences,Beijing 100049,People’s Republic of China [3]Molecular Plus and Collaborative Innovation Center of Chemical Science and Engineering,Tianjin University,Tianjin 300072,People’s Republic of China [4]Department of Physics,School of Physical Science and Engineering,Beijing Jiaotong University,Beijing 100044,People’s Republic of China [5]Research Center for Magnetic and Spintronic Materials National Institute for Materials Science,Tsukuba 305-0047,Japan

出　　处：《Nano-Micro Letters》2023年第9期536-549,共14页纳微快报（英文版）

基　　金：supported by“Key Program for International S&T Cooperation Projects of China”from the Ministry of Science and Technology of China(Grant No.2019YFE0123000);the National Natural Science Foundation of China(Grant Nos.91961125 and 21905019);Science and Technology Project of Guangdong Province(No.2020B0101370001);Chemistry and Chemical Engineering Guangdong Laboratory(No.1932004);the Project from China Petrochemical Corporation(No.S20L00151).

摘　　要：The catalytic activities are generally believed to be relevant to the electronic states of their active center, but understanding this relationship is usually difficult. Here, we design two types of catalysts for electrocatalytic urea via a coordination strategy in a metal–organic frameworks: Cu^(Ⅲ)-HHTP and Cu^(Ⅱ)-HHTP. Cu^(Ⅲ)-HHTP exhibits an improved urea production rate of 7.78 mmol h^(−1)g^(−1) and an enhanced Faradaic efficiency of 23.09% at-0.6 V vs. reversible hydrogen electrode, in sharp contrast to Cu^(Ⅱ)-HHTP.Isolated CuⅢspecies with S = 0 spin ground state are demonstrated as the active center in Cu^(Ⅲ)-HHTP, different from Cu^(Ⅱ) with S = 1/2 in Cu^(Ⅱ)-HHTP. We further demonstrate that isolated Cu^(Ⅲ)with an empty dx2-y20orbital in Cu^(Ⅲ)-HHTP experiences a single-electron migration path with a lower energy barrier in the C–N coupling process, while Cu^(Ⅱ)with a single-spin state( d_(x2-y2)^(1)) in Cu^(Ⅱ)-HHTP undergoes a two-electron migration pathway.

关 键 词：ELECTROCATALYSIS Urea synthesis Metal-organic framework Spin catalysis C-N coupling 

分 类 号：TQ441.41[化学工程—化学肥料工业] TQ426