Metal–organic frameworks (MOFs) are increasingly being investigated as electrocatalysts for the oxygen evolution reaction (OER). Despite their promising catalytic activity, many fundamental questions concerning their structure−performance relationships—especially those regarding the roles of active species—remain to be answered. Here we show the structural transformation of a Ni0.5Co0.5-MOF-74 during the OER by operando X-ray absorption spectroscopy analysis and high-resolution transmission electron microscopy imaging. We suggest that Ni0.5Co0.5OOH0.75, with abundant oxygen vacancies and high oxidation states, forms in situ and is responsible for the high OER activity observed. The ratio of Ni to Co in the bimetallic centres alters the geometric and electronic structure of as-formed active species and in turn the catalytic activity. Based on our understanding of this system, we fabricate a Ni0.9Fe0.1-MOF that delivers low overpotentials of 198 mV and 231 mV at 10 mA cm−2 and 20 mA cm−2, respectively.
This is a preview of subscription content
Subscribe to Journal
Get full journal access for 1 year
only $8.25 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Get time limited or full article access on ReadCube.
All prices are NET prices.
The authors declare that the data supporting the findings of this study are available within the paper and its Supplementary Information files.
Seitz, L. C. et al. A highly active and stable IrOx/SrIrO3 catalyst for the oxygen evolution reaction. Science 353, 1011–1014 (2016).
Suntivich, J., May, K. J., Gasteiger, H. A., Goodenough, J. B. & Shao-Horn, Y. A perovskite oxide optimized for oxygen evolution catalysis from molecular orbital principles. Science 334, 1383–1385 (2011).
Grimaud, A. et al. Activation of surface oxygen sites on an iridium-based model catalyst for the oxygen evolution reaction. Nat. Energy 2, 16189 (2016).
Suen, N.-T. et al. Electrocatalysis for the oxygen evolution reaction: recent development and future perspectives. Chem. Soc. Rev. 46, 337–365 (2017).
Grimaud, A. et al. Activating lattice oxygen redox reactions in metal oxides to catalyse oxygen evolution. Nat. Chem. 9, 457–465 (2017).
Wu, T. et al. Iron-facilitated dynamic active-site generation on spinel CoAl2O4 with self-termination of surface reconstruction for water oxidation. Nat. Catal. 2, 763–772 (2019).
Fabbri, E. et al. Dynamic surface self-reconstruction is the key of highly active perovskite nano-electrocatalysts for water splitting. Nat. Mater. 16, 925–931 (2017).
Yang, J. et al. A multifunctional biphasic water splitting catalyst tailored for integration with high-performance semiconductor photoanodes. Nat. Mater. 16, 335–341 (2016).
Jin, S. Are metal chalcogenides, nitrides and phosphides oxygen evolution catalysts or bifunctional catalysts? ACS Energy Lett. 2, 1937–1938 (2017).
Zhao, S. et al. Ultrathin metal–organic framework nanosheets for electrocatalytic oxygen evolution. Nat. Energy 1, 16184 (2016).
Shen, J.-Q. et al. Modular and stepwise synthesis of a hybrid metal–organic framework for efficient electrocatalytic oxygen evolution. J. Am. Chem. Soc. 139, 1778–1781 (2017).
Huang, J. et al. Electrochemical exfoliation of pillared-layer metal–organic framework to boost the oxygen evolution reaction. Angew. Chem. Int. Ed. 130, 4722–4726 (2018).
Wang, X.-L. et al. Exploring the performance improvement of the oxygen evolution reaction in a stable bimetal–organic framework system. Angew. Chem. Int. Ed. 57, 9660–9664 (2018).
Liu, J., Zhu, D., Guo, C., Vasileff, A. & Qiao, S.-Z. Design strategies toward advanced MOF-derived electrocatalysts for energy-conversion reactions. Adv. Energy Mater. 7, 1700518 (2017).
He, W., Ifraemov, R., Raslin, A. & Hod, I. Room-temperature electrochemical conversion of metal–organic frameworks into porous amorphous metal sulfides with tailored composition and hydrogen evolution activity. Adv. Funct. Mater. 28, 1707244 (2018).
Liberman, I., He, W., Shimoni, R., Ifraemov, R. & Hod, I. Spatially confined electrochemical conversion of metal–organic frameworks into metal-sulfides and their in-situ electrocatalytic investigation via scanning electrochemical microscopy. Chem. Sci. 11, 180–185 (2020).
Wang, L. J. et al. Synthesis and characterization of metal–organic framework-74 containing 2, 4, 6, 8 and 10 different metals. Inorg. Chem. 53, 5881–5883 (2014).
Seh, Z. W. et al. Combining theory and experiment in electrocatalysis: insights into materials design. Science 355, eaad4998 (2017).
McCrory, C. C. L., Jung, S., Peters, J. C. & Jaramillo, T. F. Benchmarking heterogeneous electrocatalysts for the oxygen evolution reaction. J. Am. Chem. Soc. 135, 16977–16987 (2013).
Song, F. & Hu, X. Ultrathin cobalt–manganese layered double hydroxide is an efficient oxygen evolution catalyst. J. Am. Chem. Soc. 136, 16481–16484 (2014).
Yano, J. et al. X-ray damage to the Mn4Ca complex in single crystals of photosystem II: a case study for metalloprotein crystallography. Proc. Natl Acad. Sci. USA 102, 12047–12052 (2005).
Funke, H., Scheinost, A. C. & Chukalina, M. Wavelet analysis of extended X-ray absorption fine structure data. Phys. Rev. B 71, 094110 (2005).
Bediako, D. K. et al. Structure–activity correlations in a nickel-borate oxygen evolution catalyst. J. Am. Chem. Soc. 134, 6801–6809 (2012).
Jiang, J. et al. Atomic-level insight into super-efficient electrocatalytic oxygen evolution on iron and vanadium co-doped nickel (oxy)hydroxide. Nat. Commun. 9, 2885 (2018).
Kirshenbaum, K. et al. In situ visualization of Li/Ag2VP2O8 batteries revealing rate-dependent discharge mechanism. Science 347, 149–154 (2015).
Mansour, A. N. & Melendres, C. A. XAFS investigation of the structure and valency of nickel in some oxycompounds. Physica B 208-209, 583–584 (1995).
Trześniewski, B. J. et al. In situ observation of active oxygen species in Fe-containing Ni-based oxygen evolution catalysts: the effect of pH on electrochemical activity. J. Am. Chem. Soc. 137, 15112–15121 (2015).
Drevon, D. et al. Uncovering the role of oxygen in Ni–Fe(OxHy) electrocatalysts using in situ soft X-ray absorption spectroscopy during the oxygen evolution reaction. Sci. Rep. 9, 1532 (2019).
Wuttig, M. et al. The role of vacancies and local distortions in the design of new phase-change materials. Nat. Mater. 6, 122–128 (2006).
Man, I. C. et al. Universality in oxygen evolution electrocatalysis on oxide surfaces. ChemCatChem 3, 1159–1165 (2011).
Diaz-Morales, O., Ledezma-Yanez, I., Koper, M. T. M. & Calle-Vallejo, F. Guidelines for the rational design of Ni-based double hydroxide electrocatalysts for the oxygen evolution reaction. ACS Catal. 5, 5380–5387 (2015).
Zhu, Y. et al. Unravelling surface and interfacial structures of a metal–organic framework by transmission electron microscopy. Nat. Mater. 16, 532–536 (2017).
Görlin, M. et al. Oxygen evolution reaction dynamics, faradaic charge efficiency and the active metal redox states of Ni–Fe oxide water splitting electrocatalysts. J. Am. Chem. Soc. 138, 5603–5614 (2016).
Friebel, D. et al. Identification of highly active Fe sites in (Ni,Fe)OOH for electrocatalytic water splitting. J. Am. Chem. Soc. 137, 1305–1313 (2015).
Smith, R. D. L. et al. Geometric distortions in nickel (oxy)hydroxide electrocatalysts by redox inactive iron ions. Energy Environ. Sci. 11, 2476–2485 (2018).
Bates, M. K., Jia, Q., Doan, H., Liang, W. & Mukerjee, S. Charge-transfer effects in Ni–Fe and Ni–Fe–Co mixed-metal oxides for the alkaline oxygen evolution reaction. ACS Catal. 6, 155–161 (2016).
Hadt, R. G. et al. X-ray spectroscopic characterization of Co(iv) and metal–metal interactions in Co4O4: electronic structure contributions to the formation of high-valent states relevant to the oxygen evolution reaction. J. Am. Chem. Soc. 138, 11017–11030 (2016).
Görlin, M. et al. Tracking catalyst redox states and reaction dynamics in Ni–Fe oxyhydroxide oxygen evolution reaction electrocatalysts: the role of catalyst support and electrolyte pH. J. Am. Chem. Soc. 139, 2070–2082 (2017).
Liu, J. et al. Free-standing single-crystalline NiFe-hydroxide nanoflake arrays: a self-activated and robust electrocatalyst for oxygen evolution. Chem. Commun. 54, 463–466 (2018).
Yang, Y., Fei, H., Ruan, G., Xiang, C. & Tour, J. M. Efficient electrocatalytic oxygen evolution on amorphous nickel–cobalt binary oxide nanoporous layers. ACS Nano 8, 9518–9523 (2014).
Shan, J., Ling, T., Davey, K., Zheng, Y. & Qiao, S.-Z. Transition-metal-doped RuIr bifunctional nanocrystals for overall water splitting in acidic environments. Adv. Mater. 31, 1900510 (2019).
Su, X. et al. Operando spectroscopic identification of active sites in NiFe Prussian blue analogues as electrocatalysts: activation of oxygen atoms for oxygen evolution reaction. J. Am. Chem. Soc. 140, 11286–11292 (2018).
Shi, Y., Yu, Y., Liang, Y., Du, Y. & Zhang, B. In site electrochemical conversion of ultrathin tannin-NiFe complex film as an efficient oxygen-evolution electrocatalyst. Angew. Chem. Int. Ed. 58, 3769–3773 (2018).
Zheng, W., Liu, M. & Lee, L. Y. S. Electrochemical instability of metal–organic frameworks: in situ spectroelectrochemical investigation of the real active sites. ACS Catal. 10, 81–92 (2020).
Miner, E. M. et al. Electrochemical oxygen reduction catalysed by Ni3(hexaiminotriphenylene)2. Nat. Commun. 7, 10942 (2016).
Görlin, M. et al. Formation of unexpectedly active Ni–Fe oxygen evolution electrocatalysts by physically mixing Ni and Fe oxyhydroxides. Chem. Commun. 55, 818–821 (2019).
Singh, C., Liberman, I., Shimoni, R., Ifaemov, R. J. & Hod, I. Pristine versus pyrolyzed metal–organic framework-based oxygen evolution electrocatalysts: evaluation of intrinsic activity using electrochemical impedance spectroscopy. Phys. Chem. Lett. 10, 3630–3636 (2019).
Trotochaud, L., Young, S. L., Ranney, J. K. & Boettcher, S. W. Nickel–iron oxyhydroxide oxygen-evolution electrocatalysts: the role of intentional and incidental iron incorporation. J. Am. Chem. Soc. 136, 6744–6753 (2014).
He, W., Gao, H.-M., Shimoni, R., Lu, Z.-Y. & Hod, I. Synergistic coupling of anionic ligands to optimize the electronic and catalytic properties of metal–organic framework-converted oxygen-evolving catalysts. ACS Appl. Energy Mater. 2, 2138–2148 (2019).
Ravel, B. & Newville, M. ATHENA, ARTEMIS, HEPHAESTUS: data analysis for X-ray absorption spectroscopy using IFEFFIT. J. Synchrotron Radiat. 12, 537–541 (2005).
Sayers, D. E. & Bunker B. A. in X-ray Absorption: Principles, Applications, Techniques of EXAFS, SEXAFS and XANES (eds Koningsberger, D. C. & Prins, R.) 211–253 (Wiley, 1988).
Rehr, J. J. & Albers, R. C. Theoretical approaches to X-ray absorption fine structure. Rev. Mod. Phys. 72, 621–654 (2000).
Bunău, O. & Joly, Y. Self-consistent aspects of X-ray absorption calculations. J. Phys. Condens. Matter 21, 345501–345510 (2009).
Guda, S. A. et al. Optimized finite difference method for the full-potential XANES simulations: application to molecular adsorption geometries in MOFs and metal–ligand intersystem crossing transients. J. Chem. Theory Comput. 11, 4512–4521 (2015).
Solé, V. A. et al. A multiplatform code for the analysis of energy-dispersive X-ray fluorescence spectra. Spectrochim. Acta B 62, 63–68 (2007).
Kresse, G. & Furthmüller, J. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys. Rev. B 54, 11169–11186 (1996).
Perdew, J. P., Burke, K. & Ernzerhof, M. Generalized gradient approximation made simple. Phys. Rev. Lett. 77, 3865–3868 (1996).
Kohn, W. & Sham, L. J. Self-consistent equations including exchange and correlation effects. Phys. Rev. 140, A1133–A1138 (1965).
Tkalych, A. J., Zhuang, H. L. & Carter, E. A. A density functional + U assessment of oxygen evolution reaction mechanisms on β-NiOOH. ACS Catal. 7, 5329–5339 (2017).
Bajdich, M., García-Mota, M., Vojvodic, A., Nørskov, J. K. & Bell, A. T. Theoretical investigation of the activity of cobalt oxides for the electrochemical oxidation of water. J. Am. Chem. Soc. 135, 13521–13530 (2013).
Maintz, S., Deringer, V. L., Tchougréeff, A. L. & Dronskowski, R. LOBSTER: a tool to extract chemical bonding from plane‐wave based DFT. J. Comput. Chem. 37, 1030–1035 (2016).
We appreciate financial support from the Strategic Priority Research Program of Chinese Academy of Sciences (XDB36000000, Z.T.), the National Key Basic Research Program of China (2016YFA0200700, Z.T.), the National Natural Science Foundation of China (21890381 and 21721002, Z.T.; 11605225, J.D.), the Frontier Science Key Project of Chinese Academy of Sciences (QYZDJ-SSW-SLH038, Z.T.) and K.C. Wong Education Foundation (Z.T.). S.Z. acknowledges financial support from the FH Loxton fellowship of the USYD. J.D. acknowledges support from the Youth Innovation Promotion Association, CAS. C.-T.H. acknowledges support from the Young Elite Scientists Sponsorship Program by CAST. J.Z. thanks the National Key Research and Development Program of China (2017YFA0403400). We sincerely appreciate V. Yachandra and B. Lassalle providing the XAS data for Ni(OH)2 and NiOOH references. We thank R. Chen for help and suggestions.
The authors declare no competing interests.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Zhao, S., Tan, C., He, CT. et al. Structural transformation of highly active metal–organic framework electrocatalysts during the oxygen evolution reaction. Nat Energy 5, 881–890 (2020). https://doi.org/10.1038/s41560-020-00709-1
Nature Materials (2022)
Nature Communications (2022)
Axial coordination regulation of MOF-based single-atom Ni catalysts by halogen atoms for enhanced CO2 electroreduction
Nano Research (2022)
Self-templated formation of twin-like metal-organic framework nanobricks as pre-catalysts for efficient water oxidation
Nano Research (2022)
Science China Chemistry (2022)