Design, Synthesis and Evaluation of Photoswitches for Molecular Solar Thermal Energy Storage Systems

To meet the future energy demands and handle climate changes, new sustainable energy sources must be developed. Over the last decades, great scientific progress on harvesting solar energy has been made, but storing the energy is still a challenge. One way to store solar energy is in a compound that absorbs solar energy while being converted to a metastable isomer through a photoisomerization process, a technique referred to as molecular solar thermal energy storage (MOST). In this work, the norbornadiene/quadricyclane system, a promising candidate for MOST, was evaluated and new synthetic methods were developed to obtain a series of novel norbornadiene derivatives in an efficient way. Photophysical characterization of the series revealed a better solar spectrum match and high energy storage densities (114–124 kJ/mol) compared to previous series. Quantum yields for the photoisomerization processes were between 28–58% and the half-lives of the photoisomers in the range of hours to days. Solvent effects on the norbornadiene/quadricyclane system were studied, showing a pronounced effect on both the half-lives of the photoisomers and on the photoisomerization process when going from polar to non-polar solvents. Additionally, bicyclooctadiene derivatives were synthesized and for the first time evaluated as MOST candidates. The series exhibited very high storage densities (143–153 kJ/mol) compared to the corresponding norbornadiene derivatives (52–63 kJ/mol) and could switch back and forth for 645 cycles without significant degradation. The absorption profile and half-lives of the photoisomers need further improvement for MOST applications, but the molecular engineering concepts presented here can be used to develop future MOST systems based on the bicyclooctadiene/tetracyclooctane system. Altogether, this work illustrates the importance of detailed molecular design and the importance of the local environment of the photoswitches for obtaining desired MOST properties

Scalable Synthesis of Norbornadienes via in situ Cracking of Dicyclopentadiene Using Continuous Flow Chemistry

The norbornadiene (NBD)-quadricyclane (QC) photoswitch has recently attracted attention due to its use in molecular solar thermal energy systems (MOST). Normally for device testing, several grams are needed. One way of synthesizing NBDs efficiently is through the Diels-Alder reaction between alkynes and cyclopentadiene. However, scaling up the reaction can be troublesome in a research lab environment. Also, dicyclopentadiene needs cracking before utilization which is a time-consuming step. Here, we developed a method where we both scale up the synthesis in a single reaction step that involves both in situ cracking of dicyclopentadiene and the direct reaction of cyclopentadiene with acetylene derivatives using a tubular coiled stainless steel flow reactor. As a proof-of-concept, we synthesized six different NBD compounds and scaled the synthesis to produce 87 g of a novel NBD in 9 h. The NBD is further characterized, showing promising properties for MOST applications. Our new method shows that flow chemistry is an attractive technique for the fast and efficient synthesis of large quantities of NBDs, needed to develop future real-life devices and applications

Macroscopic heat release in a molecular solar thermal energy storage system

The development of solar energy can potentially meet the growing requirements for a global energy system beyond fossil fuels, but necessitates new scalable technologies for solar energy storage. One approach is the development of energy storage systems based on molecular photoswitches, so-called molecular solar thermal energy storage (MOST). Here we present a novel norbornadiene derivative for this purpose, with a good solar spectral match, high robustness and an energy density of 0.4 MJ kg-1. By the use of heterogeneous catalyst cobalt phthalocyanine on a carbon support, we demonstrate a record high macroscopic heat release in a flow system using a fixed bed catalytic reactor, leading to a temperature increase of up to 63.4 \ub0C (83.2 \ub0C measured temperature). Successful outdoor testing shows proof of concept and illustrates that future implementation is feasible. The mechanism of the catalytic back reaction is modelled using density functional theory (DFT) calculations rationalizing the experimental observations

Norbornadienes for molecular solar thermal energy storage

Over the last decade, there has been great scientific progress in terms of harvesting solar energy but the area of storing energy is still facing challenges. One approach to store solar energy is via photoinduced isomerization of chemical bonds, referred to as molecular solar thermal energy storage (MOST). Norbornadiene is a promising candidate molecule for this purpose, since upon irradiation isomerization occurs to form the metastable quadricyclane. The reaction is reversible and back conversion can be triggered to release the energy as heat. In this work, a new synthetic approach was developed to obtain 2-bromo-3-chloronorbornadiene that serves as an important starting material for further functionalization of norbornadienes. Through the developed procedure, a series of norbornadienes, decorated with electron donating and accepting substituents were synthesized. Photophysical characterization revealed that norbornadienes with cyano acceptor groups and ethynyl-substituted aromatic donor groups show a good solar spectrum match and high energy storage densities (296 – 545 kJ/kg). The obtained quantum yields for the photoisomerization processes were between 28 – 58% and the half-lives of the corresponding quadricyclanes in the range of 5 – 22 hours for the compounds with an ethynyl linker, and 55 days for the quadricyclane with similar substituents but without the ethynyl linker. The synthesized compounds illustrate the challenge in optimizing all parameters for an efficient MOST system in a single molecule system. For a deeper understanding of the relation between the structure and the properties, more variations of norbornadienes have to be synthesized and evaluated in future research

Measuring Gradients in Gaseous Elemental Mercury Using a Passive Air Sampler

Mercury (Hg) monitoring is necessary to constrain the global Hg cycle and to develop policies for reducing Hg emissions. Passive air samplers (PAS) are an accessible method for monitoring gaseous elemental mercury (GEM). I tested the suitability of PAS for recording GEM gradients at widely varying scales. Vertical gradients on the scale of centimeters to tens of meters measured over soil and within a forest allowed for the observation of GEM uptake in growing vegetation, the determination of the air-surface exchange direction, and the estimation of evaporative fluxes from contaminated soil. When PAS were deployed above a field with known soil contamination, slightly different spatial contamination patterns suggest horizontal GEM advection. on a continental scale, the PAS were also used to map annually averaged GEM levels across South and Central America. Accounting for the effect of wind speed on the PAS sampling rate is necessary to distinguish small concentration differences.M.Sc.2021-12-29 00:00:0

A Convenient Route to 2-Bromo-3-chloronorbornadiene and 2,3-Dibromonorbornadiene

Substituted norbornadienes are useful in a wide range of applications, including molecular solar-thermal (MOST) energy storage systems. An important precursor for 2,3-substituted norbornadienes is 2-bromo-3-chloronorbornadiene, where the two halogen atoms can be substituted selectively through two consecutive Suzuki cross-coupling reactions. Previous routes to 2-bromo-3-chloronorbornadiene have used 1,2-dibromoethane as a brominating agent, a substance known to be carcinogenic and the use of which is restricted in certain countries. Herein is reported a one-pot route to 2-bromo-3-chloronorbornadiene in 50% yield using p-toluenesulfonyl bromide as a bromine source. In addition, the procedure has been adapted to allow synthesis of 2,3-dibromonorbornadiene in 37% yield

Investigation of extinguishing water and combustion gases from vehicle fires

Sales of electric vehicles doubled in 2021 compared to the previous year and nearly 10% of the global new-car sales were electric in 2021. In the recent IEA Global EV Outlook 2022, Norway, Iceland, and Sweden were reported to have the highest electric car shares of the new car market: 86%, 72% and 43%, respectively. Electrification of transport has multiple benefits but has also raised some concerns. For example, the use of rare metals and their sourcing are concerns from an environmental perspective, the capacity of the electricity network and the limited number of charging stations has been raised as an implementation barrier, and the new fire and explosion risks of batteries have caused concerns amongst users, property owners and rescue services alike society.Fires starting in the traction batteries (lithium-ion battery) are rare but if the battery catches fire, it can be difficult to extinguish since the battery packs are generally well protected and difficult to reach. To cool the battery cells, firefighters must prolong the application duration of suppression agent. This generally results in use of large amounts of water/fire extinguishing agent, which could carry pollutants into the environment.In this work, extinguishing water from three vehicle fires as well as from one battery pack fire has been investigated. Large-scale fire tests were performed with both conventional and electric vehicles. Tests were performed indoors at RISE, Borås, which also allowed analysis of combustion gases for both inorganic and organic pollutants in the gas and liquid phase.It was found that nickel, cobalt, lithium, manganese and hydrogen fluoride appeared in higher concentrations in the effluents from the battery electric vehicle and lithium-ion battery compared to from the internal combustion engine vehicle. However, lead was found in higher concentrations in the effluents from the internal combustion engine vehicle, both in the combustion gases as well as in the extinguishing water. Ecotoxicity analysis showed that extinguishing water from all vehicle and battery fires analysed in this work were toxic against the tested aquatic species.Funding: Energimyndigheten 48193-2</p

Urban furniture using SBR rubber granule "Creati" - B

El reciclaje de llantas en Bogotá es cada vez más común, a partir de ello se ha desarrollado un nuevo material o materia prima, el cual es usado generalmente en los “Playgrounds” de los niños, baldosas para gimnasios, etc. Sin embargo, dentro del gremio procesador de dicho componente no existen nuevas alternativas de producto y están en busca de ello, teniendo en cuenta las capacidades físicas del gránulo de caucho. La búsqueda por nuevas aplicaciones para el caucho reciclado debe orientarse a obtener productos con mayor valor agregado, para que esta alternativa planteada sea económicamente atractiva, tenga mayores posibilidades de comercialización y consecuentemente al aumentar los volúmenes de utilización de caucho reciclado, se disminuya el impacto ambiental de la disposición de los residuos de caucho. (Arroyave, Velásquez, Vásquez, 2017.) Es de aquí donde nace la idea de generar nuevos productos, teniendo en cuenta las capacidades que este material tiene. Se ha encontrado la oportunidad de diseñar mobiliario urbano, por el impacto que puede tener en la problemática identificada.In Bogota the recycling of tires is becoming pretty common day by day, this process has developed a new material, usually used in kids playgrounds, gym floors, etc. However, within the guild that processes this material, there are not other alternatives of products, where the rubber granule can be used, at least in Colombia, the guilds are looking for other opportunities where the raw material can be exploited. The search of new applications for the recycled must be oriented to obtain product with more value in the market, so this posible alternatives economically speaking can be por attractive, and could have more chances of commercialization and consequently by increasing the volumes of recycled rubber utilization, the environmental impact of the disposal of rubber waste is decreased.(Arroyave, Velásquez, Vásquez, 2017.) Here is where the idea of creating new products is born, having in mind the capacities that this material have. Has been found the opportunity of designing urban furniture, for the impact that it may have in the identified problem.Diseñador (a) IndustrialPregrad