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.
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We appreciate the financial support from National Research Fund for Fundamental Key Project (2014CB931801 and 2016YFA0200700, Z.T.), Instrument Developing Project of the Chinese Academy of Sciences, Grant No. YZ201311, CAS-CSIRO Cooperative Research Program, Grant No. GJHZ1503, “Strategic Priority Research Program” of the Chinese Academy of Sciences (Grant No. XDA09040100), National Natural Science Foundation of China (91023007 and 20773033 (S.L.), 21025310 (Z.T.)), and the New Century Excellent Talents in University, Outstanding Young Funding of Heilongjiang Province, Jialin Xie Fundation of Institute of High Energy Physics, CAS (542016IHEPZZBS501 (J.D.)) and NSFC (Grant No. 11605225). We thank L. Gu for providing high-angle annular dark-field scanning transmission electron microscope tests. All DFT calculations were undertaken on the NCI National Facility in Canberra, Australia, which is supported by the Australian Commonwealth Government.
The authors declare no competing financial interests.
Supplementary Methods, Supplementary Figures 1–41, Supplementary Tables 1–5. (PDF 4660 kb)
Crystallographic information for NiCo-UMOFNs. (CIF 6 kb)
Crystallographic information for Ni-UMOFNs. (CIF 6 kb)
Crystallographic information for Co-UMOFNs. (CIF 6 kb)
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Zhao, S., Wang, Y., Dong, J. et al. Ultrathin metal–organic framework nanosheets for electrocatalytic oxygen evolution. Nat Energy 1, 16184 (2016) doi:10.1038/nenergy.2016.184
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