NANO.IL.

Metal-Organic Framework Based Photo-electrochemical Cells

Raya Ifraemov Department of Chemistry and Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva, Israel

Photo-electrochemical cells (PECs), which directly convert sunlight into chemical fuels, are considered to be one of the most promising and economically feasible future technologies for producing alternative energy sources. [1-2] Metal−organic frameworks (MOFs) are a sub-class of coordination polymers, consisting of organic linkers bounded to metal-based nodes. [3] These materials display exceptional properties such as large surface area, permanent porosity and chemically tunable structures. By a clever selection of the right building blocks, it is possible to tune and modify the MOF chemical and photo physical properties. [4]

In recent years, MOFs containing light absorbing moieties or catalytic units have been successfully used in photocatalytic reactions. Nevertheless, due to the low electronic communication between adjacent MOF installed light chromophores, only a few examples exist for PECs based solely on MOFs.

Herein, we show for the first time that the kinetics of photo-induced charge transfer at the MOF-electrolyte interface is the main factor which determines the polarity of accumulated charge at the MOF-based electrode. As a result, unlike standard PECs, the photo-electrochemical behavior of a MOF-based electrode can be switched from photo-anodic to photo-cathodic by an appropriate choice of redox mediators in the electrolyte. Moreover, we demonstrate that a MOF-based photo-cathode is capable of photo-electrocatalytic production of molecular hydrogen, thus providing a compelling proof of principle for the utilization of MOF-based PECs for solar fuel generation.

References:

[1] M. G. Walter, E. L. Warren, J. R. McKone, S. W. Boettcher, Q. Mi, E. A. Santori, N. S.

Lewis, Chem. Rev. 2010, 110, 6446–6473.

[2] H. Furukawa, N. Ko, Y. B. Go, N. Aratani, S. B. Choi, E. Choi, A. Ö. Yazaydin, R. Q. Snurr,

  1. O’Keeffe, J. Kim, O. M. Yaghi, Science. 2010, 329, 424 LP-428

[3] H. Furukawa, K. E. Cordova, M. O’Keeffe, O. M. Yaghi, Science. 2013, 341.

[4] M. C. So, G. P. Wiederrecht, J. E. Mondloch, J. T. Hupp, O. K. Farha, Chem. Commun.

2015, 51,3501–3510.









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