Co@NH₂-MIL-125(Ti): cobaloxime-derived metal–organic framework-based composite for light-driven H₂ production

Abstract

Co@NH2-MIL-125(Ti): Cobaloxime-derived Metal-Organic Framework-based Composite for Light-driven H2 Production Nasalevich, M.A.; Becker, R.; Ramos-Fernandez, E.V.; Castellanos, S.; Veber, S.L.; Fedin, M.V.; Kapteijn, F.; Reek, J.N.H.; van der Vlugt, J.I.; Gascon, J. Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. We present a synthetic strategy for the efficient encapsulation of a derivative of a well-defined cobaloxime proton reduction catalyst within a photoresponsive metal-organic framework (NH 2 -MIL-125(Ti)). The resulting hybrid system Co@MOF is demonstrated to be a robust heterogeneous composite material. Furthermore, Co@MOF is an efficient and fully recyclable noble metal-free catalyst system for lightdriven hydrogen evolution from water under visible light illumination. Broader contextThe development of new strategies for the efficient valorization of solar light is one the most important challenges we face nowadays. Among the different possibilities, dihidrogen molecule is considered as one of the possible future energy carriers allowing for CO 2 -free energy cycle. Although the photocatalytic water splitting was the rst photocatalytic reaction to be discovered, no photocatalytic systems for this reaction have been industrially applied. This is both due to the fact that most discovered catalysts rely on the use of noble metals and to the low activities achieved so far by alternative catalysts. The application in this eld of materials such as metal-organic frameworks (MOFs) can be a game changer in this research eld. MOFs have been proven to be photoactive and their optical properties can be easily tuned towards visible light operation. The current challenge lies in the development of more appropriate active sites for the desired photocatalytic cycle. In this manuscript, we report a new strategy to achieve this goal. By introducing a derivative of the well-known molecular Co-based electrocatalyst Co-dioxime-diimine into the pores of a photo-active NH 2 -MIL-125(Ti) following a 'Ship-in-a-bottle' strategy, we were able to synthesize a highly active photocatalyst composite free of noble metals, and fully recyclable. Because of the novelty and the implications of this work, we feel that it might appeal to the interdisciplinary readership of energy and environmental science. The journal has previously been an important forum for the research topics touched upon in this paper (new earth abundant materials and their application in (photo) catalysis and hydrogen evolution from water under visible light illumination). We would be glad t...

Understanding metal–organic frameworks for photocatalytic solar fuel production

“…Accordingly, a second strategy is to employ MOFs as a passive container for the encapsulation of a light absorbing photocatalyst. 30,31 These active species are often homogeneous catalysts based on precious metals, and by encapsulating 29 or covalently bonding them to the framework, leaching has been successfully prevented. 22 This strategy was also employed on a UiO-66 framework, using RuIJbpy) 3 as a photosensitizer.…”

“…24 Fortunately, MOFs are not solely limited to being a static scaffold, thus promoting synergistic and cooperative interactions among the MOF and the encapsulated catalyst is a more stimulating third approach, where charge transfer between MOF and guest is achieved. 29 This method was applied, for example, on a UiO-67 framework consisting of biphenyl-4,4′-dicarboxylic acid combined with Ir-based ligands. When loaded with Pt nanoparticles, 19 it showed remarkable activity for hydrogen evolution due to the efficient electron transfer from the Ircomplex to Pt.…”

“…[27][28][29] In this context, different approaches have been recently followed: from the use of MOFs as containers for encapsulating light absorbing photocatalysts 22,24,30 to exploiting ligand-to-metal charge transfer (LMCT) within the MOF or even inducing charge transfer from the MOF to encapsulated catalysts. 29,31 Regardless of the promising discoveries made in the past few years, a lot of progress is still needed. Proof of the interest in this application of MOFs is the unprecedented number of reviews (almost as many as the number of papers on the topic) that have appeared in the literature over the last two years.…”

Photochemical Hydrogen Production with Metal–Organic Frameworks

“…In 2015, Gascon and coworkers employed the same framework NH 2 -MIL-125(Ti) as photosensitizing platform for a molecular Co-oxime-diimine catalyst as guest molecule inside the framework's pores [55]. The molecular catalyst was build up inside the pores by first soaking the MOF with the oxime ligand and subsequent addition of CoBr 2 leading to the formation of the catalyst.…”

“…4 Photochemical hydrogen production making use of photosensitizing framework. Pt-nanoparticles [54] or cobaloxime [55] were used as catalysts observed with TEA, EDTA or methanol. The authors attributed the need of TEOA to the weak oxidation power of the organic linker.…”