Wednesday, 30 November 2016

Ultrathin metal–organic framework nanosheets for electrocatalytic oxygen evolution

Source: "Ultrathin metal–organic framework nanosheets for electrocatalytic oxygen evolution", Nature Energy 1, Article number: 16184 (2016), doi:10.1038/nenergy.2016.184, Published Online: 28 November 2016

Authors:

Shenlong Zhao - 1, 2, 3; Yun Wang, Huijun Zhao - 4; Juncai Dong - 5; Chun-Ting He - 6; Huajie Yin - 1, 4; Pengfei An, Jing Zhang - 5; Kun Zhao, Chao Gao, Jiawei Lv, Jianqi Zhang, Abdul Muqsit Khattak, Niaz Ali Khan, Zhixiang WeiZhiyong Tang - 1; Xiaofei Zhang, Jinxin Wang - 3; Lijuan Zhang - 1, 2

1 CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China
2 State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150080, China
3 School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150080, China
4 Centre for Clean Environment and Energy, Gold Coast Campus, Griffith University, Queensland 4222, Australia
5 Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
6 MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, China

Abstract

The design and synthesis of efficient electrocatalysts are important for electrochemical conversion technologies. The oxygen evolution reaction (OER) is a key process in such conversions, having applications in water splitting and metal–air batteries. Here, we report ultrathin metal–organic frameworks (MOFs) as promising electrocatalysts for the OER in alkaline conditions. Our as-prepared ultrathin NiCo bimetal–organic framework nanosheets on glassy-carbon electrodes require an overpotential of 250 mV to achieve a current density of 10 mA cm−2. When the MOF nanosheets are loaded on copper foam, this decreases to 189 mV. We propose that the surface atoms in the ultrathin MOF sheets are coordinatively unsaturated—that is, they have open sites for adsorption—as evidenced by a suite of measurements, including X-ray spectroscopy and density-functional theory calculations. The findings suggest that the coordinatively unsaturated metal atoms are the dominating active centres and the coupling effect between Ni and Co metals is crucial for tuning the electrocatalytic activity.

Read more at: http://www.nature.com/articles/nenergy2016184