| 1. |
- Dreos, Ambra, 1987, et al.
(author)
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Liquid Norbornadiene Photoswitches for Solar Energy Storage
- 2018
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In: Advanced Energy Materials. - : Wiley. - 1614-6832 .- 1614-6840. ; 8:18
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Journal article (peer-reviewed)abstract
- Due to high global energy demands, there is a great need for development of technologies for exploiting and storing solar energy. Closed cycle systems for storage of solar energy have been suggested, based on absorption of photons in photoresponsive molecules, followed by on-demand release of thermal energy. These materials are called solar thermal fuels (STFs) or molecular solar thermal (MOST) energy storage systems. To achieve high energy densities, ideal MOST systems are required either in solid or liquid forms. In the case of the latter, neat high performing liquid materials have not been demonstrated to date. Here is presented a set of neat liquid norbornadiene derivatives for MOST applications and their characterization in toluene solutions and neat samples. Their synthesis is in most cases based on solvent-free Diels-Alder reactions, which easily and efficiently afford a range of compounds. The shear viscosity of the obtained molecules is close to that of colza oil, and they can absorb up to 10% of the solar spectrum with a measured energy storage density of up to 577 kJ/kg corresponding to 152 kJ mol(-1) (calculated 100 kJ mol(-1)). These findings pave the way towards implementation of liquid norbornadienes in closed cycle energy storage technologies.
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| 2. |
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| 3. |
- Dreos, Ambra, 1987, et al.
(author)
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Three-Input Molecular Keypad Lock Based on a Norbornadiene-Quadricyclane Photoswitch
- 2018
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In: Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 9:21, s. 6174-6178
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Journal article (peer-reviewed)abstract
- Copyright © 2018 American Chemical Society. The photo- and acidochromic properties of a new generation norbornadiene derivative have been harnessed for the realization of a three-input keypad lock, where a specific sequence of inputs induces a unique output. Reversible quadricyclane/norbornadiene photoisomerization is reported, and this rare feature allows the first example of a norbornadiene-based molecular logic system. The function of this system is clearly rationalized in terms of the interconversion scheme and the absorption spectra of the involved species.
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| 4. |
- Jevric, Martyn, 1973, et al.
(author)
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Norbornadiene-Based Photoswitches with Exceptional Combination of Solar Spectrum Match and Long-Term Energy Storage
- 2018
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In: Chemistry - A European Journal. - : Wiley. - 1521-3765 .- 0947-6539. ; 24:49, s. 12767-12772
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Journal article (peer-reviewed)abstract
- Norbornadiene-quadricyclane (NBD-QC) photoswitches are candidates for applications in solar thermal energy storage. Functionally, they rely on an intramolecular [2+2] cycloaddition reaction, which couples the S0 landscape on the NBD side to the S1 landscape on the QC side of the reaction and vice-versa. This commonly results in an unfavourable correlation between the first absorption maximum and the barrier for thermal back-conversion. This work demonstrates that this correlation can be counteracted by using steric repulsion to hamper the rotational motion of the side groups along the back-conversion path. It is shown that this modification reduces the correlation between the effective back-conversion barrier and the first absorption maximum and also increases the back-conversion entropy. The resulting molecules exhibit exceptionally long half-lives for their metastable forms without significantly affecting other properties, most notably solar spectrum match and storage density.
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| 5. |
- Manso, Mads, 1991, et al.
(author)
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Molecular solar thermal energy storage in photoswitch oligomers increases energy densities and storage times
- 2018
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In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723 .- 2041-1723. ; 9:1
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Journal article (peer-reviewed)abstract
- Molecular photoswitches can be used for solar thermal energy storage by photoisomerization into high-energy, meta-stable isomers; we present a molecular design strategy leading to photoswitches with high energy densities and long storage times. High measured energy densities of up to 559 kJ kg(-1) (155 Wh kg(-1)), long storage lifetimes up to 48.5 days, and high quantum yields of conversion of up to 94% per subunit are demonstrated in norbornadiene/quadricyclane (NBD/QC) photo-/thermoswitch couples incorporated into dimeric and trimeric structures. By changing the linker unit between the NBD units, we can at the same time fine-tune light-harvesting and energy densities of the dimers and trimers so that they exceed those of their monomeric analogs. These new oligomers thereby meet several of the criteria to be met for an optimum molecule to ultimately enter actual devices being able to undergo closed cycles of solar light-harvesting, energy storage, and heat release.
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| 6. |
- Wang, Zhihang, 1989
(author)
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Exploring Devices for Molecular Solar Thermal Energy Storage Systems
- 2018
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Licentiate thesis (other academic/artistic)abstract
- The sun is considered to be one of the most abundant and renewable sources of energy. During recent last decades, technologies for solar energy capture and storage have been significantly investigated. An attractive way to store solar light, is to use photochromic molecules that can capture and store solar energy in chemical bonds. When energy is required, it can be released “on demand”, so called Molecular Solar Thermal Energy Storage (MOST). In this thesis, the method and technique for MOST characterization is discussed. Two MOST candidates based on the Dihydroazulene/Vinylheptafulvene (DHA/VHF) and Norbornadiene/Quadricyclane (NBD/QC) have been then characterized. The DHA/VHF system has been evaluated in both indoor and outdoor devices. Moreover, potential catalysts for conversion of the NBD/QC MOST candidate have been identified by testing 15 different metal complexes and salts. Selected candidate was physisorbed on to the surface of activated carbon for a macroscopic heat release demonstration. A record high absolute temperature of up to 83.2 °C was finally observed, thus showing a proof-of-principle from solar energy capture, storage to energy release of the MOST concept in functional devices.
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