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. 2016 Sep 30:7:13032.
doi: 10.1038/ncomms13032.

A ketone/alcohol polymer for cycle of electrolytic hydrogen-fixing with water and releasing under mild conditions

Ryo Kato  1 , Keisuke Yoshimasa  1 , Tatsuya Egashira  1 , Takahiro Oya  1 , Kenichi Oyaizu  1 , Hiroyuki Nishide  1
Affiliations

A ketone/alcohol polymer for cycle of electrolytic hydrogen-fixing with water and releasing under mild conditions

Ryo Kato et al. Nat Commun. .

Abstract

Finding a safe and efficient carrier of hydrogen is a major challenge. Recently, hydrogenated organic compounds have been studied as hydrogen storage materials because of their ability to stably and reversibly store hydrogen by forming chemical bonds; however, these compounds often suffer from safety issues and are usually hydrogenated with hydrogen at high pressure and/or temperature. Here we present a ketone (fluorenone) polymer that can be moulded as a plastic sheet and fixes hydrogen via a simple electrolytic hydrogenation at -1.5 V (versus Ag/AgCl) in water at room temperature. The hydrogenated alcohol derivative (the fluorenol polymer) reversibly releases hydrogen by heating (80 °C) in the presence of an aqueous iridium catalyst. Both the use of a ketone polymer and the efficient hydrogen fixing with water as a proton source are completely different from other (de)hydrogenated compounds and hydrogenation processes. The easy handling and mouldable polymers could suggest a pocketable hydrogen carrier.

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Conflict of interest statement

The authors declare no competing financial interests.

Figures

Figure 1
Figure 1. Hydrogen fixing and releasing by the fluorenone/fluorenol polymer.
(a) A sheet of the fluorenone and fluorenol hydrogel on a 5 g scale and the fluorenol sheet sealed up with a gas-barrier bag (after hydrogen releasing). (b) Schematic representation of hydrogen-fixing and -releasing cycle. (c) Preparation scheme of the fluorenone and fluorenol polymer.
Figure 2
Figure 2. Charge storage and electrolytic hydrogenation of the fluorenone polymer.
Charging/discharging curves of the fluorenone polymer at a rate of 10 C measured in the AN electrolyte. Inset: schematic image of charge propagation in the polymer layer and conversion plots of the fluorenone to fluorenol unit in the fluorenone polymer layer electrolytically reduced in the AN/water electrolyte. Theoretical capacity of the fluorenone polymer-coated electrode was 52 mC per 0.2 mg polymer. The dashed line indicates the theoretical conversion with the passed charge; the error bars for the s.d. calculated from five samples.
Figure 3
Figure 3. Proton exchange reaction of fluorenol/fluorenone dianion.
(a) 1H NMR measurements of fluorenol in the presence of the fluorenone dianion were conducted in AN-d3. Inset, expanded cyclopentane and hydroxyl proton spectra of fluorenol. (b) Schematic image of proton propagation in the polymer layer.
See this image and copyright information in PMC

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