题目：Unpaired 3d Electron on Atomically Dispersed Cobalt Centre inCoordination Polymers to Regulate both ORR Activity andSelectivity
作者：Yuebin Lian,[a,b] Wenjuan Yang,[c] Chufeng Zhang,[a,b] Hao Sun, [a,b], Zhao Deng, [a,b] Wenjie Xu,[d] Li Song,[d] Zhongwen Ouyang,[e] Zhenxing Wang,[e] Jun Guo,[f] Yang Peng*[a,b]
[a,b] Soochow Institute of Energy and Material Innovations, College of Physics, Optoelectronics and Energy, Soochow University, Suzhou 215006, China.
Provincial Key Laboratory for Advanced Carbon Materials and Wearable Energy Technologies, Soochow University, Suzhou 215006, China.
[c] International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen, 518060, China.
[d] National Synchrotron Radiation Laboratory, CAS Center for Excellence in Nanoscience, University of Science and Technology of China, Hefei, Anhui 230029, China.
[e] Wuhan National High Magnetic Field Center & School of Physics, Huazhong University of Science and Technology, Wuhan, 430074, P. R. China
[f] Analysis and Testing Center, Soochow University, Suzhou 215123,China.
摘要：Reversible oxygen conversion is of vital importance for various green energy technologies. Herein we synthesize a series of bimetallic coordination polymers by varying the Ni/Co ratio and using HITP (HITP = 2, 3, 6, 7, 10, 11-hexaiminotriphenylene) as the ligand, with the aim to interrogate the role of metal centers in modulating the activity of oxygen reduction reaction (ORR). The differences in crystallographic structure, spin character, electric conductivity, and coordination states are elaborately compared for both Co3HITP2 and Ni3HITP2, revealing the former with unpaired 3d electrons possessing less coplanarity but more radical features. As a result, despite of a reduced crystallinity and conductivity, the best ORR activity comparable to 20% Pt/C is obtained for Co3HITP2, signifying the 3d orbital configuration of the metal center in promoting ORR. More importantly, both experimental and DFT investigations unveil a transition of ORR pathway from four-electron for Co3HITP2 to twoelectron for Ni3HITP2 owing to different intermediate binding energetics. Further in conjunction with the considerable OER activities, rechargeable zinc-air batteries using Co3HITP2 as the air cathode catalyst demonstrate excellent energy efficiency and operation stability.