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AN INTRODUCTION TO MOLECULAR THERMAL ENERGY STORAGE A Seminar Report Submitted To

Chhattisgarh Swami Vivekanand Technical University Bhilai (India)

In partial fulfillment of the award of degree of

BACHELOR OF ENGINEERING in

CHEMICAL ENGINEERING Under the Guidance of

Dr. H.Kumar (Advisor/Professor) Department of Chemical Engineering Submitted by Praful Verma(AR0920)

DEPARTMENT OF CHEMICAL ENGINEERING RAIPUR INSTITUTE OF TECHNOLOGY APRIL-MAY 2019

ACKNOWLEDGEMENT I would

like to make my deepest appreciation and gratitude to Dr. H. Kumar

(Advisor/Professor,Chemical Engineering Department, RITEE, Raipur),for his valuable guidance, constructive criticism and encouragement during every stage of this report work. The technical discussions with sir were always been highly interactive. We are thankful to Dr. D. Mukhopadhyay (HOD), Chemical Engineering Department, RITEE, Raipur for being uniformly excellent advisor. I owe a depth of gratitude to all faculties of Chemical Engineering Department ,I would like to give special thanks to all staffs of the Chemical Engineering Department for their all-time technical, moral support to carrying out the project. Finally, thanks to all who directly or indirectly have been supporting and standing by all the time.

With Regards Praful Verma (AR0920)

DECLARATION I undersigned solemnly declare that the seminar report entitled “An introduction to molecular thermal energy storage” is based on my work carried out during the course of study under the supervision of Dr. H.Kumar (Advisor /Professor, Chemical Engg. Department, RITEE, Raipur). I assert that the statements made and conclusions drawn are an outcome of the report work. I further declare that to the best of my knowledge and belief that the report does not contain any part of any work which has been submitted for the award of any other degree/diploma/certificate in this University or any other University.

Date:Place:-

(Signature of the Candidate) Praful Verma (AR0920)

CERTIFICATE This is to certify that the work in this seminar report entitled “An introduction to molecular thermal energy storage” submitted by Praful Verma in partial fulfillment of the requirements of the prescribed curriculum for Bachelor of Engineering in Chemical Engineering, Session 201519 in the Department of Chemical Engineering, Raipur Institute of Technology, Raipur is carried out by his under my supervision and guidance. To the best of my knowledge to matter embodied in the seminar report is his bonafide work.

Guide Dr. H. Kumar (Advisor/Professor) Department of Chemical Engineering Raipur Institute of Technology,Raipur, (C.G.)

Introduction A solar panel is a great power generating system because it doesn't release greenhouse gas. But storing solar energy requires lots of high capacity lithium-ion batteries, which are expensive to produce and have serious environmental impacts. According to a recent publication in the journal Energy & Environmental Science, a group of chemical engineers from Sweden's Chalmers University of Technology has developed an innovative method to store thermal energy from the Sun, a system called the Molecular Solar Thermal Energy Storage or MOST. Everyone knows that in the summer the Sun emits a lot of heat. Wouldn't it be nice to store the thermal energy for later usage? With this idea in mind, the Swedish scientists had their eyes set on a new type of solar energy storage device that relies on a photosensitive compound norbornadiene. Norbornadiene is in liquid form at room temperature. It can re-arrange its chemical structure when heat up, transforming into a high-energy isomer that stores the heat at an energy density of 0.4 megajoules (MJ) per kilogram. When present with a cobalt salt-based catalyst, the molecule returns to its original form, releasing the trapped energy. During a press release, Dr. Kasper Moth-Poulsen, the senior author of the paper and a material scientist from Chalmers says: "The energy in this isomer can now be stored for up to 18 years. And when we come to extract the energy and use it, we get a warmth increase which is greater than we dared hope for." In a proof of concept experiment, the scientists demonstrated that the norbornadiene-based liquid fuel managed to heat up MOST's catalytic reactor by 63.4°C or 145 F, a new record among similar thermal energy storage devices. What's more, heat-trapping isomer can be stored and transported at room temperature with minimal energy loss. The team of researchers has already set up a prototype on the roof of a university building, putting the energy storage device to test in the real world. Through continuous improvement and potential investments, they hope to increase the energy storage capacity of the new liquid fuel and deploy MOST commercially in the next ten years. 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 °C (83.2 °C 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.

Paper published on 6 Nov 2018 The barrier to solar energy has always been storage. Now, bottled sunshine has a shelf-life of 18 years.   

Researchers have invented a liquid isomer that can store and release solar energy. The team has solved problems other researchers have previously encountered. The discovery could lead to more widespread use of solar energy. In the last year, a team from Chalmers University of Technology, Sweden, essentially figured out how to bottle solar energy. They developed a liquid fuel containing the compound norbornadiene that—when struck by sunlight—rearranges its carbon, hydrogen, and nitrogen atoms into an energy-storing isomer, quadricyclane. Quadricyclane holds onto the energy, estimated to be up to 250 watt-hours of energy per kilogram, even after it cools and for an extended period of time. For use, it's passed through a cobalt-based catalyst, at which point the energy is released as heat. The team's research could be a breakthrough in making solar energy transportable and thus even more usable for meeting real-world energy needs. What's more, the team has been adjusting the molecular makeup of their fuel so that it doesn't break down as a result of storage and release cycles. It can be used over and over again. "We've run it though 125 cycles without any significant degradation," according to researcher Kasper Moth-Poulsen. As a result, the scientists envision a round-trip energy system they call MOST, which stands for Molecular Solar Thermal Energy Storage.

The MOST system (Chalmers University of Technology) In the MOST system, the liquid runs through a concave solar thermal collector that has a pipe running across its center. The collector focuses sunlight on that pipe, and the fuel running through it, causing the transformation of norbornadiene into quadricyclane. The charged fuel then flows through transparent tubing into storage tanks, or it can be diverted and shipped elsewhere for use. Says Moth-Poulsen in the Chalmers press release, "The energy in this isomer can now be stored for up to 18 years. And when we come to extract the energy and use it, we get a warmth increase which is greater than we dared hope for." To release the fuel's energy, it's passed through the catalyst in which a chemical reaction occurs to convert the fuel back into liquid whose temperature has been boosted by 63°C or 145°F. So, for example, if the fuel goes into the catalyst at 20°C, it comes out at 83°C. In this form, the fluid can be used for heating a home or business, or be used in any other system reliant on heated liquid. "You could use that thermal energy for your water heater, your dishwasher or your

clothes dryer," MIT's Jeffrey Grossman tells NBC MACH. "There could be lots of industrial applications as well."

This last year has been a key time (Johan Bodell) Kasper Moth-Poulsen holds the tube containing the MOST catalyst The first iteration of the Chalmers fuel was revealed about a year ago, and in the intervening months, the researchers have been working toward the robust behavior they're now seeing, even beyond achieving that remarkable 18-year storage potential. "We have made many crucial advances recently, and today we have an emissions-free energy system which works all year around," says Moth-Poulsen. Though other researchers have experimented with similar uses for norbornadiene, their fuels broke down after just a few cycles before their research was abandoned. Those earlier fuels also didn't hold the energy very long. The Chalmers team also originally had to mix their isomer with flammable toluene. Now, however, they've worked out a way to use the isomer without dangerous additives.

Storing solar energy As the world moves to renewable energy, solar energy has proven to be among the most attractive: Sunlight is free and releasing its energy produces no pollution or harmful effects. One remaining limiting factor has been finding ways of storing solar energy that are as clean as solar energy itself. Much work is being down with batteries, but it's difficult to produce power cells without using toxic materials. The MOST system offers an exciting new angle to pursue.

Paper published on 10 March 2018

Solar Storage System Saves Energy for Winter Researchers from Chalmers University of Technology in Sweden have improved a molecularbased system that can store solar energy collected in the summer so it can be used during the dark winter months. Last year, the researchers found a molecule made from carbon, hydrogen and nitrogen that is capable of storing solar energy. The molecule is converted to an energy-rich isomer when it is hit by sunlight. The researchers used the isomer in its liquid form for a new solar energy system dubbed MOST (Molecular Solar Thermal Energy Storage), which they have since improved upon. “The energy in this isomer can now be stored for up to 18 years,” Kasper Moth-Poulsen, a professor at the Department of Chemistry and Chemical Engineering and leader of the research team, said in a statement. “And when we come to extract the energy and use it, we get a warmth increase which is greater than we dared hope for.” The solar thermal collector is a concave reflector with a pipe in the center that can track the path of the Sun across the sky, focusing the rays to a point where the liquid leads through the pipe. In the updated version of MOST, the liquid captures energy from sunlight in a solar thermal collector on the roof of a building. The energy is then stored at room temperature to minimize how much energy is lost in the process. Building on last year’s breakthrough, the researchers created a catalyst that can control the release of the stored energy by acting as a filter where the liquid flows to produce a reaction that warms the liquid by 63 degrees Celsius. When the liquid’s temperature is increased as it is pumped through the filter, the molecule is returned to its original form so that it can be reused in the warming system. When the energy is needed for domestic heating system, it can be drawn through the catalyst so that the liquid heats up. The liquid can then be sent back to the roof to collect more energy without producing any emissions of damaging the molecule. In the original system, liquid had to be partly composed of toluene—a flammable chemical that is potentially dangerous. In the new version of MOST, the researchers were able to remove the toluene and use just the energy storing molecule. The researcher’s next plan to combine all of their advancements into one coherent system so that it can be a commercially viable system within the next decade. They also hope to extract more energy into the system and increase the temperature to at least 110 degrees Celsius.

“There is a lot left to do,” Moth-Poulsen said. “We have just got the system to work. Now we need to ensure everything is optimally designed.

Paper published in 2015 The sun’s rays are a renewable energy source offering huge potential. Kasper Moth-Poulsen is developing a promising new concept using artificial molecules that can capture, store and release solar energy, so that it can be used when the sun is not shining.

Kasper Moth-Poulsen Associate Professor of Applied Chemistry Wallenberg Academy Fellow 2014 Institution: Chalmers University of Technology Research Conversion of solar energy into chemical energy in molecules

field:

New technology that can make use of solar energy efficiently and cheaply is in demand throughout the world. Development is driven by climate change, and society’s huge need for renewable technology. “These are very exciting times for researchers in this field. Hopefully, our technology can be developed quickly enough to contribute to current progress in this area,” Kasper says. At present solar energy cannot be stored. It has to be used straight away, when the sun is shining. This is a big problem, particularly in our cooler northern climes. The technology being developed by Kasper and his team will enable solar energy to be used when and where it is needed. “Traditional technology uses solar cells and a battery, but we are trying to create an integrated single unit. Our concept MOST – Molecular Solar Thermal – converts solar energy into chemical energy, which is stored in specially designed molecules. When we need the energy, we can trigger the molecules to release it, so that it can be used to heat buildings, for example, or be converted into electricity.”

An idea born in California Kasper studied chemistry at University of Copenhagen, and then took a PhD in Molecular Electronics. Some years later, in sunny California, when he was a postdoc at the University of California, Berkeley, he began work on thermal energy storage. When Kasper moved to Chalmers University of Technology in 2011, he brought with him the idea of storing solar energy in molecules to be developed by his own research team. The technology is now being further developed with funding from the Knut and Alice Wallenberg Foundation. “The grant gives us the courage to try somewhat riskier projects, with a slightly longer timeframe. I can have a larger research team, which has an enormous impact on the kind of issues we can address. A large grant of this kind is also a form of recognition and gives me greater confidence as a researcher.” “Together with researchers at UC Berkeley we have conducted experiments showing that we can store and release solar energy using the same molecules. This is in fact an old concept from the 1970’s that has gained new impetus in recent years. Using the potential offered by new computer technology, we are better able to design molecules and understand how they work.” Kasper mentions that the results, which were published in 2012, attracted much international attention. Last year his research team made another important breakthrough when they showed they could improve the efficiency of storage and energy conversion by these molecules. The research team has grown from three to 15 people in two years. This in itself is a challenge for a young research leader, but with more researchers, he will also be able to address bigger and more difficult issues. Kasper believes that the interdisciplinary environment at Chalmers offers particularly good prospects for success for a project of this kind.

“I am a chemist, but I work a lot with physicists, including Paul Erhart here in the same corridor, who is also a Wallenberg Academy Fellow. He calculates our molecules, and makes quantum mechanical computer models of how they should work. Then we test them.”

A nano catalyst Kasper explains that the idea is for it to be possible to reuse the same molecules over and over again. The entire process takes place in a closed system without harmful environmental impacts in the form of emissions of carbon dioxide or chemicals. “The research we are doing is not just about developing a new molecule; it covers the whole process from storage to release of the energy.” One challenge the team faces is to improve the absorption of solar energy by the molecule, to make use of as much sunlight as possible. The silicon-based solar cells on the market convert only up to about 32 percent of sunlight into energy. Kasper is aiming for greater efficiency. “We are also making strenuous efforts using nanotechnology to develop a catalyst that will help to release the stored energy. It is a long process, but we have recently found a new catalyst that seems to work.” The higher the temperature of the thermal energy extracted from the molecules, the more potential applications there will be. “At the moment we are achieving about 50°C, but we would really like to go much further than that – to 100°C or more. We’ll have to see how far we get.”

Interest from industry Molecules and nano catalysts are being developed in the chemistry lab on the same floor as Kasper’s office. Here there is also a technology lab in which the researchers carry out demonstrations of the energy storage concept. They start with very simple experiments using solar lamps that illuminate the liquid with the molecules. At the moment a class of molecules called norbornadienes are being tested. “Over the next five years we hope to be able to move from basic research to more realistic demonstrations of the concepts.” The solar power industry has already shown interest in the technology. But Kasper wants to make some more progress before entering into definite collaborations. “Although this is pure basic research, we hope that when the project is over in 5 – 10 years, we will have come a good way along the road towards future niche applications. Step by step, depending on how successful we are, we will hopefully be able to identify potential of various kinds.”

Paper published on 31 March 2017 Researchers at the Chalmers University of Technology in Gothenburg, Sweden, have demonstrated efficient solar energy storage in a chemical liquid. The team has shown that it is possible to convert energy from the sun directly into energy stored in the chemical bonds of a chemical fluid — a molecular solar thermal system. That energy can be transported and released on demand, with full recovery of the storage medium.

Solar energy on demand Professor Kasper Moth-Poulsen, who is leading the research, gives for consideration that the development of efficient methods for solar energy storage is a key challenge for a future society where the majority of the energy is derived from renewable energy. “In this context,” he says, “we are developing molecular solar thermal systems.” The head of the Molecular Materials research group in Chalmers’ Department of Chemistry and Chemical Engineering explains that these systems are based on molecules that can absorb light and directly convert it into stored chemical energy though an isomerisation process that is based on the organic compound norbornadiene, which converts into quadricyclane when exposed to light. Furthermore, this process is reversible, so that the energy can be released as heat when needed and the molecule recovered to enable multiple solar energy storage and release cycles. The process is inherently a closed cycle, and there is no combustion or emission associated with it.

Most efficient molecules “The molecules that we have developed are the most efficient we have worked with. They enable the conversion of 1.1% of incoming sunlight into stored chemical energy in our test device,” reveals the professor. “We further demonstrate for the first time that the chemical liquid can be combined with traditional low-temperature water heating, without compromising the efficiency of the water heating system.”

Efficiency The professor notes that based on his team’s previously published estimates, they believe that it should be possible to reach 10–15% solar energy storage efficiency in the molecular solar thermal system, which he says could be used in domestic or industrial applications. Combined with water heating, a hybrid system might be able to make use of 85–95% of the incoming energy.

Advantages and promise for the future of solar energy Moth-Poulsen points out several advantages of Chalmers’ molecular solar thermal system over previous solar energy storage solutions: “The heat is stored at room temperature without any need for insulation, the energy density in the storage medium is very high compared with traditional methods, and the used materials can potentially be fabricated at a low price, without the need of any precious metals or other limited resources.” What promise does this innovative technique hold for the future of solar energy? “We hope that we — with further development — can develop a functional system that can contribute to an environmentally friendly energy transition towards a society where energy is produced from renewables,” the professor says.

Commercialization and outlook Moth-Poulsen says he and his colleagues are currently exploring different strategies for making the pioneering solar energy storage solution commercially viable. The timeline to market will depend on specific applications and whether they will be able to attract the right type of collaborators outside academia. “We will continuously work towards improving the performance of the system towards more efficient solar energy conversion, longer storage times and increased energy densities,” the expert concludes. “Also, we will be working on controlling the heat release process in an optimal way.

Scientists Reveal Strange Molecule That Can Store Sun's Energy For 18 Years Nov 6, 2018

One of the biggest hurdles to widespread adoption of renewables is energy storage. Where do you store energy when the sun's not shining, the wind's not blowing, etc.? A Swedish research team believes it found the breakthrough renewables was looking for, a solar thermal fuel that can store the sun's energy for up to 18 years. Hydrocarbons, in part, became the world's dominant energy source because they are relatively cheap to extract, can be stored for long periods of time, and can be utilized immediately. These factors make it a great source for energy to power on-demand. As batteries continue to develop in their capacity to store energy and for long periods of time, they have begun to supplant hydrocarbons, i.e. electric vehicles. As an alternative to batteries, the specialized solar thermal fluid can hold the sun's energy for long periods of time and expel that energy on demand. Unlike batteries, which discharge electricity, the solar thermal fuel emits heat when activated through a catalyst. This means the fluid would be ideal for heating residential and commercial homes. The fuel is composed of carbon, hydrogen and nitrogen molecules. The molecules can be seen in the figure below, with the original fuel source being norbornadiene molecules. When these molecules are hit by sunlight, some of the bonds between atoms are rearranged to form quadricyclane.

Conversion of the solar fuel from norbornadiene to quadricyclane ROYAL SOCIETY OF CHEMISTRY

This chemical conversion into a different molecular structure called an isomer traps energy within the molecule. The energized version of the molecule is stable, with strong chemical bonds. This is key in that the stable molecule can sit for nearly two decades without losing the stored energy. To release the energy, the molecule can be passed through a catalyst, which rearranges the chemical bonds back to norbornadiene and with it releases quite a lot of heat. The team found that the catalyst process heats up the fuel by 63 degrees Celsius (113 degrees Fahrenheit). This means if the ambient temperature in the room is around 70 degrees Fahrenheit, the fluid would heat up to 183 degrees F. The heated fluid could then be used to heat homes, commercial buildings, etc.

A schematic of how the thermal fuel process works.CHALMERS UNIVERSITY OF TECHNOLOGY

With additional testing and optimization, the team believes they can produce a molecule that can heat up the fuel by over 176 degrees F. The fuel could then be considered for electricity generation. While there's quite a lot of additional work to be done, the research team believes the technology could be commercially available in a decade. This is partially due to the increased interest from investors in the technology. The development and commercialization of this thermal fuel could be another key component in the migration to renewable energy sources. The thermal fuel requires no outside input beyond the sun and operates in a closed loop system. As we continue to develop novel technologies and advance existing technologies, the transition to renewable resources not only becomes easier but becomes economically favorable.

Trevor Nace is a PhD geologist, founder of Science Trends, Forbes contributor, and explorer. Follow his journey @trevornace.

Energy & Environmental Science 2019 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 1C (83.2 1C 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.

Broader context Thermal energy can be used for a broad range of applications such as domestic heating, industrial process heating and in thermal power processes. One promising way to store solar thermal energy is so-called molecular solar thermal (MOST) energy storage systems, where a photoswitchable molecule absorbs sunlight and undergoes a chemical isomerization to a metastable high energy species. Here we present an optimized MOST system (providing a high energy density of up to 0.4 MJ kg_1), which can store solar energy for a month at room temperature and release the thermochemical energy ‘‘on demand’’ in a closed energy storage cycle. In addition to a full photophysical characterization, solar energy capture of the present system is experimentally demonstrated by flowing the MOST system through an outdoor solar collector (E900 cm2 irradiated area). Moreover, catalyst systems were identified and integrated into an energy extraction device leading to high temperature gradients of up to 630C (830C measured temperature) with a short temperature ramp time of only a few minutes. The underlying step-by-step mechanism of the catalytic reaction is modelled in detail using quantum chemistry calculations, successfully rationalizing the experimental observations.

Introduction According to the 2015 United Nations Climate Change Conference (COP21) Paris agreement on climate change, global emissions must be reduced by 60% prior to 2050.1 The energy consumption is, however, predicted to double in the next 40 years due to an increasing world population. For this reason, it is prudent to explore other sustainable energy sources, in addition to electricity generated by either wind power or solar cells. The latter, driven from sunlight, has always been considered to be an abundant renewable energy source; in fact, the International Energy Association (IEA) has predicted that solar energy could provide over 25% of the global energy needs around the deadline of the Paris agreement. In recent decades, solar energy has been widely investigated, with a more than 900% increase in installed capacity, demonstrating a

rapid expansion of its use. Nevertheless, one of the greatest challenges for mass implementation of solar energy technology is the intermittence of supply and load levelling. Effective storage of solar energy, therefore, is fundamentally important for future development of this energy source. One promising solution is the molecular solar thermal energy storage (MOST) system, where a photoswitchable parent molecule that absorbs sunlight undergoes a chemical isomerization to a metastable high energy species. This concept has been proven viable by incoporating the photoswitch into solid materials or into liquid based systems. In the case of solution based MOST, a catalyst can be used to release this stored energy ‘‘on demand’’ in the form of heat, and as a result regenerating the parent molecule. In contrast to more traditional solar thermal concepts, the MOST system operates in an entirely different manifold, by converting photons to stored chemical energy at room temperature, meaning that e.g. no insulation materials are needed for practical devices. However, many factors have to be considered for the optimal design of a photoswitchable molecule for MOST applications. Ideally, a strong absorption in the UV-visible region of the solar spectrum by the parent molecule with no absorption by the corresponding high energy isomer is preferred. Other prerequisites include a high photoisomerization quantum yield, exceptional robustness and also a low molecular weight, so as to maximize the energy density. For solutions, it’s preferable that the solvent features a low heat capacity, yet can accommodate a large amount of photoswitching. Several photochromic motifs have been identified as potential candidates, such as the dihydroazulene/vinylheptafulvene couple, anthracene dimerization, azobenzene, azaborinine derivative Dewar isomers,difulvalenediruthenium complexes, and norbornadiene–quadricyclane. The latter system has gained increased attention partly due to its high energy density, but relatively little effort has been dedicated to releasing the stored energy, which is the focus of this work. A representation of the MOST concept and a possible domestic implementation. Sunlight is collected and stored via photochemical reaction under flow conditions. When energy is required, a solution of the metastable molecule can be passed through a catalytic bed reactor to release the energy in the form of heat, which could be used for, in this instance, heating water or creating steam. In order for MOST to be viable, the energy has to be storable for a long period of time, thus requiring a high energy barrier (DH‡ therm) for the thermal conversion from the high energy isomer to the parent molecule. Yet, at the same time, the heat release upon demand must be rapid and efficient. For the norbornadiene (NBD)–quadricyclane (QC) couple, it has been shown that a rapid conversion of unsubstituted QC to NBD can be effected electrochemically as well as through the use of a catalyst. Both approaches give rise to a release of the energy by lowering the activation barrier (DH‡ cat) from the photoisomer to the parent molecule. In addition, to be suitable for use in a closed cycle operational device capable of undergoing successive cycles, heterogeneous catalysis should be employed.Previous research has identified many catalysts, including various transition metal salts and complexes.However, the main challenge remains to incorporate an effective catalyst into a working device based on a sunlight absorbing MOST system.