Digital twins are already being used in areas such as aircraft and automotive design. So what do they have to do with mental health? Can we make a digital model of a living molecular system?
Blog posts
For most physical illnesses, there are objective tests to determine what a patient’s issue is. Currently, diagnosis of mental health conditions is more subjective, as it relies on patient’s descriptions of their own symptoms. What if digital tools could identify biomarkers which were clearly linked to specific mental illnesses?
Schizophrenia is a chronic mental illness affecting around 20 million people worldwide and is most common in young men (according to the World Health Organisation). How are the tools of genetics and AI being used to improve treatment?
Depression and anxiety are the most common mental health illnesses, affecting 264 million and 284 million people worldwide, respectively – equivalent to 3.4% and 3.8% of the global population. However, it’s thought that many cases are unreported – the real figures are expected to be double what is recorded. What’s going on at a molecular level in the brain during depression and anxiety? How does medication change this?
Mental health is the sum of our psychological, emotional, and social wellbeing. Combined, these help us cope with life’s difficulties. Yet a worryingly substantial proportion of the population will suffer from poor mental health at some point in their lives. This is the first in a series of blogs exploring the molecular basis of mental health, and how a molecular perspective can help develop new treatments.
In this blog series, we’ve investigated why solar fuels are needed, what properties are needed by solar materials such as Fe2O3 (haematite), and how novel materials with more suitable properties could be found. In this, our final post, we will see how computers can help find the perfect material for the production of solar fuels. Finally, we will introduce the key steps that are usually done in a research lab to build a tangible device, a device that can be used to produce a “solar fuel”.
By Dr Miriam Regue and Dr Minsu Park, Research Associates in the Department of Chemical Engineering.
Predicting the properties of potential light absorber materials is an excellent starting point to evaluate their suitability as candidates for solar fuels devices. For example, the Computational Materials Science group focuses on modelling and simulating materials for solar energy conversion applications. Computational modelling allows us to predict the absorption properties as well as understand the inherent features of existing or new material candidates before building a tangible device.
For instance, oxide perovskites are a class of light absorbing materials that are gaining significant interest in the field of solar fuels. Some examples are lanthanum ferrite (LaFeO3), praseodymium ferrite (PrFeO3) or gadolinium ferrite (GdFeO3). They are made of abundant elements and offer good visible light absorption but their understanding for solar fuels production is still scarce.
Computational approaches
Computers are an excellent tool to predict material properties. They are so powerful that we can use them to run calculations and predict some of these unknown material properties. The results of these calculations help scientists to design a more efficient experimental approach to improve the solar fuel performance. They can acquire knowledge on how thick the material needs to be for boosting light absorption, how chemical modifications can affect the performance and how different structures of the same material can alter the optoelectronic properties.
Once the theoretical knowledge is gathered, the race on designing an efficient device begins. From a practical point of view, the successful material candidate must be stable in water conditions for at least 2,000 hours and provide a solar to fuel efficiency of at least 10%.
But how can we make a device that can be used to produce a ‘solar fuel’?
The first stage of the experimental design is to test the light absorber material at a lab scale. This is usually done following two different experimental approaches: (1) By depositing the light absorber material on top of a flat conductive surface to form a photoelectrode. This photoelectrode generates electric current upon solar light irradiation (photoelectrochemistry) and the electric current is used to produce the solar fuel. (2) Or alternatively, by directly immersing a powdered material in a reactor (photocatalysis) that is illuminated with solar light. Using this approach we can also measure and quantify the amount of solar fuel (i.e H2 (and O2), CO, CH4 …) produced (see the below diagram). Although both approaches are feasible for solar fuels production, thephotoelectrochemical approach is often the preferred one mainly for safety reasons, but also due to better reproducibility in results.
As simple as it seems though, there are numerous challenges that experimentalists face, such as low efficiencies and performances, and poor product selectivity and scaling-up reproducibility. Different experimental approaches are currently under investigation to address some of these issues. In our research group, we follow various novel approaches to improve the response of these materials and to understand and describe their behaviour. For instance, we recently discovered that (1) mimicking the shape of natural desert roses on TiO2, (2) using a polymer as a template for the preparation of LaFeO3 and Fe2O3, and (3) loading copper and graphene oxide on novel halide perovskite materials improves the performance and efficiency of the water splitting process and solar CO2 conversion to methane and carbon monoxide upon solar light irradiation (below diagram).
So, which technology readiness does solar fuel production have right now? Will we ever power our home using a stand-alone H2 device? Is our society ready to produce commodity chemicals (plastic, fertilizers, clothes…) from waste CO2 using solar light?
Unfortunately, photoelectrochemical approaches are still in lab-scale studies, but tremendous improvement has been achieved since their discovery in 1972 by Fujishima and Honda.2 Researchers have achieved solar-conversion efficiencies of 10 % for ca. 40 h and it is expected that similar or even higher efficiencies will be obtained by 2025 on square metre devices with the final goal to achieve a decentralised and local production of solar fuel (H2) at a household level in the near future. Direct CO2 capture and solar conversion is on a similar technological readiness as H2 production. However, the success of this technology relies on the capability of coupling direct CO2 capture technologies with photoelectrochemical set-ups.
But undoubtedly, what will mark the deployment of these disruptive technologies and ensure a proper share in the current market is the ability to compete economically with conventional methods of hydrogen and carbon-based products production. Currently, steam methane reforming produces H2 at an average cost of ~ 1.40 $/ kg (it depends on natural gas price), is significantly lower than what is currently estimated for photoelectrochemical devices ( 9 – 11 $ kg-1).[1] However, if the research community manages to overcome the current technical barriers, the cost of hydrogen via photoelectrochemical methods could reach 2 – 4 $ kg-1.[2] This will be an extraordinary breakthrough that will pave the way for solar hydrogen to be included in the future energy mix.
Bibliography
- R. J. Detz, J. N. H. Reek and B. C. C. Van Der Zwaan, Energy Environ. Sci., 2018, 11, 1653–1669. DOI: https://doi.org/10.1039/C8EE00111A
- B. A. Pinaud et al, Energy Environ. Sci., 2013, 6, 1983–2002. DOI: https://doi.org/10.1039/C3EE40831K
Last time we saw the potential of solar fuels to produce clean green hydrogen. But it turns out solar energy can also be used to convert CO2 and methane, potent greenhouse gasses, into high-value products for the production of fertilizers, plastics or even pharmaceuticals. In this post we find out about the materials needed to do that!
By Dr Miriam Regue and Dr Minsu Park, Research Associates in the Department of Chemical Engineering.
Solar fuels have the potential to not only help us reach net zero carbon emissions, but play an important role in the making of new carbon-based products following a sustainable circular economy approach (Fig. 1).
However, despite the great promise and potential of solar fuels, they are still far from being commercialised. But why? What is hindering the deployment of solar fuels, and what limitations are we facing?
The ideal solar material
It is both hard and challenging to give just one simple answer to this question. Remember from our first post that we said certain materials can absorb the energy from sunlight and transform it into electrical current? Well at the moment, the ideal light absorber materials that would lead the transition to a solar fuel-based society are still being researched. In fact, the “ideal” light absorber must fulfil several requirements. For one, it must absorb the widest possible range of the solar spectrum, so we can make the most of the solar energy to use it for the production of solar fuels. Secondly it must be made of elements with a plentiful supply on the Earth’s crust.
Solar materials and the radiation spectrum
To understand the first requirement, we must consider the solar spectrum. It is composed of three different bands; infrared, visible and ultraviolet radiation. Infrared and visible radiation are the majority bands, accounting for 52 – 55 % and 42 – 43 % of the spectrum respectively, whereas ultraviolet radiation represents only 3 to 5 %. To absorb the complete range of the solar spectrum is still a challenging process within the research community. Unfortunately, the infrared radiation – the largest band in the solar spectrum – is not very energetic which makes it very difficult for activating the light absorber material and trigger the production of solar fuels. Therefore, light absorber materials can mainly be activated by either visible or ultraviolet radiation. But, considering the largest portion of visible radiation in the solar spectrum, the “optimum” light absorber material should be particularly good at absorbing light from the visible range (400 – 700 nm). Each material has a specific and unique absorption range – called band gap energy. The band gap energy and the absorption energy are indirectly related. The highest the absorption wavelength, the lowest the band gap energy. It turns out that the optimal band gap values that correspond to the visible wavelengths of the solar spectrum range from 1.9 to 3.1 eV.
Solar materials and elemental abundance
The second requirement, that our light absorber material must be made of elements with a plentiful supply on the Earth’s crust, can be solved by choosing a green-coloured elements of The Element scarcity periodic table (Fig. 2). Haematite (α-Fe2O3), which is one of the renowned materials for solar water splitting, is a promising light absorber candidate: It has a band gap energy of 2.1 eV, meaning that it can absorb near the range of 590 nm and it is made of large abundant elements, iron (Fe) and oxygen (O). This makes it fulfil both our requirements!
Ultimately, the efficiency of the process also depends on several inherent features of the light absorber material, such as their energetic properties and their ability to convert the absorbed solar energy to the desired solar fuel. In fact, these are the most challenging features to control and as mostly agreed by the research community, probably the limiting step of the solar fuel production. Finding the proper material able to meet all these requirements at once is a cumbersome process and requires the collaboration of scientists and engineers from different fields of expertise such as theoreticians and experimentalists. In fact, although Fe2O3 (haematite) fulfils the first and second requirements (made of abundant elements and suitable light absorption), its inherent properties are still not good enough to produce solar fuels in an efficient manner.
But if existing materials such as Fe2O3 (haematite) or TiO2 are not good enough for solar fuels, how can we improve them? Read our next blog about how can we find novel materials with more suitable properties.
Turning sunlight into a liquid fuel that is an abundant, sustainable, storable, and portable source of energy might sound like the fantasy machinations of a sci-fi novel. However, the reality is possibly even more exciting: energy in that sunlight can be used to convert CO2 and methane, potent greenhouse gasses, into high-value products for the production of fertilizers, plastics or even pharmaceuticals.
In this series of blog posts we will find out how this is possible, how scientists are on a quest to find the “perfect material” for the production of solar fuels, and how the research community is trying to produce hydrogen, using sunlight, sufficiently cheaply that it will pave the way for solar hydrogen to be included in the future energy mix.
In our first post we find out how solar fuels have the potential to produce clean green hydrogen.
By Dr Miriam Regue and Dr Minsu Park, Research Associates in the Department of Chemical Engineering.
“Climate change is one of the biggest threats that we are facing today” – is a phrase we have probably heard countless times at this stage. It may have lost some of their shock factor with repetition, or have made some of us too disheartened by their meaning that we choose to ignore it, but its message gets more urgent year by year.
As most of us already know, human-made CO2 emissions are one the main triggers of climate change, contributing directly to global warming. However, the evidence for just how rapid and irreversible this change is happening is stark. Over the last 20 years alone, the concentration of CO2 in the atmosphere has increased sharply, reaching a record value of 416 ppm of atmospheric CO2 (June 2020), a ⁓13 % increase since 2000 [1]. That is according to the Mauna Launa Observatory in Hawaii, the institution with the longest record of direct CO2 measurements in the atmosphere. Indeed these concentrations are almost double the amount of atmospheric CO2 that has ever been on Earth at any time over the past 400,000 years. Data shows that this continuous rise in CO2 is directly related to the combustion of fossil fuels such as oil, natural gas or coal that, unfortunately, our society still widely uses on a daily basis. Failing to reduce our reliance on fossil fuels to heat our homes, power our transport systems, and produce our goods, will cause unprecedented change, and damage, to both our way of life and the natural world alike.
Solar fuels to replace fossil fuels
The sharp increase in CO2 over the last 20 years clearly shows that scientists, engineers and policy makers must work together, and quickly, to ensure that the energy we produce and the products that we make are not as a result of releasing CO2 into the atmosphere. Indeed scientists and engineers are currently devoting considerable efforts to find efficient and scalable approaches for the production of alternative clean fuels. One revolutionary and promising alternative to conventional fossil fuels are what are known as Solar Fuels. As the name might suggest, these are fuels produced by capturing the abundant solar energy that reaches the Earth’s surface. But as our title asks, how can we turn sunlight into a fuel?
Certain materials can absorb the energy from sunlight and transform it into another form of energy, including electric current – the same principle used in a solar panel. The electric current generated can then be used to split water (H2O) into its components, hydrogen (H2) and oxygen (O2). Currently, the main industrial method for mass hydrogen production is done using a process known as steam methane reforming – which emits CO2. But hydrogen gas produced from solar energy is emission free and among the most promising solar fuels currently being investigated. One huge potential application of solar hydrogen is as an emission-free fuel to power the hydrogen vehicles of the future!
In fact, the European Union has recently released a green hydrogen strategy as part of the European Green Deal in which it aims to deploy green hydrogen at a large scale to ensure decarbonization of industries, transport, buildings and power by 2030. Therefore, it is now the perfect time to boost the potential of solar hydrogen to ensure it can be part of such a fascinating but challenging transition to a fossil-free economy.
In the next blog we will discover that in spite of the great promise and potential of solar fuels, they are still far from being commercialised.
Bibliography
- NASA, relentless rise carbon dioxide. https://climate.nasa.gov/climate_resources/24/graphic-the-relentless-rise-of-carbon-dioxide/
The final part of our blog looks to the future, including introducing electrocatalysts, which could give the potential game-changer of both generating electricity and producing fuels like petrol and diesel using naturally abundant substances. We also see how predicting a specific catalyst for any reaction will soon be within reach. It looks like the best days of the alchemist might still be ahead.
By Aditya Sengar, Research Associate in the Department of Bioengineering.
Ever since the industrial revolution the world has been in a crisis mode. We need more efficient and cleaner energy over the dirty fossil fuels we currently have. The science of catalysis has been challenging the energy sector by constantly developing processes that either reduce or abandon the usage of fossil fuels. It is unfortunate that the biggest bottlenecks for adaptation of such processes are political. The USA signing out of the Paris Agreement on climate change, and China’s increasing reliance on coal, do not help the cause. We have seen historically that man-made devastating events can be tackled when global powers work together in a timely manner. I remember as a child reading about the depleting ozone layer. The problem started in 1980s when it was realised that typical refrigerants, called chlorofluorocarbons (CFCs), used in our air-conditioners and refrigerators cause breakdown of ozone molecules making us vulnerable to harmful ultraviolet (UV) light from the sun. Global events like Montreal Protocol in 1987 and Kyoto Protocol in 1997 started a wave of cooperation among politicians. Scientists unleashed the power of catalysis by experimenting with different catalysts to find ways to produce variations of carbon, hydrogen, and chlorine that are ozone friendly. The plan worked and the usage of new refrigerants (hydrofluorocarbons- HFCs) have already brought the size of ozone hole at its minimum since 1982. Unfortunately, it turns out that these HFCs contribute to greenhouse gas emissions and countries are now working to replace HFCs with more environmentally friendly natural refrigerants.
The ozone story can be used to ask a bigger question: Wouldn’t it be remarkable to be able to generate electricity or produce useful chemicals like petrol, diesel, and ammonia using naturally abundant substances like water, carbon dioxide, and nitrogen rather than fossils? This is the exact question chemists are trying to solve with electrocatalysis. Let us dig a bit deeper into this.
Electrocatalysis: Existential crisis to the fossil fuel economy
Electrolysis uses an electric current to force a reaction to occur over a catalytic electrode. Under normal circumstances, this reaction would be extremely unlikely to occur. Consider hydrogen fuel cells. In the previous blog, we discussed how the hydrogen fuel cell economy is challenging the current electricity generation and distribution landscape. The only downside of hydrogen fuel cells is the usage of coal and natural gas to produce hydrogen. Using electrocatalysis, a water molecule is split using electricity, generally produced from a renewable source (wind, solar), to produce hydrogen and oxygen. In another instance, carbon dioxide from the atmosphere is reduced catalytically to form important products like methane (called green methane), hydrocarbons, carbon monoxide etc. The present research challenges mainly surround the choice of optimum catalyst and the ability to scale up a successful experiment on a lab scale to a commercial scale.
The challenge of finding the optimum catalyst
Certain metals and compounds have a natural tendency to increase reaction rates. Ironically, gold and silver, the metals that alchemists wanted to synthesize, have excellent catalytic properties. Finding the perfect catalyst, however, remains a challenge. Major research labs rely on spectroscopy methods like X-ray photoelectron spectroscopy (XPS) or Nuclear magnetic resonance spectroscopy (NMR) to determine catalyst dynamics during an ongoing reaction. The data is used to compare the catalyst dynamics from other samples to find the optimum catalyst. In a positive turn of events, the advent of supercomputers has been like a holy grail to catalyst science. With more processing power, scientists can model the catalyst dynamics on molecular levels and transform the information to something reaction engineers can understand. Computational techniques like Density Functional Theory (DFT), microkinetic modelling and kinetic Monte Carlo (kMC) are used together to predict catalyst properties and reaction dynamics a priori.
As computational power progresses, the dream of predicting a specific catalyst for any reaction will soon be within reach and will provide scientists to engage in public undertakings of world crisis at much earlier stages.
Conclusion
Catalysis as a science is almost 200 years old. The 20th century has seen an explosion of industrial use of catalysts spurred by major historic events like the world war, and the need to find energy replacement by countries. In 2020, the global catalyst market stands at a net worth of USD 35 billion and is expected to reach USD 48billion by 2027 with a 4.4% annual growth rate. It looks small but estimates show that catalysts are used in 90 percent of U.S. chemical manufacturing processes and to make more than 20 percent of all industrial products with a direct or indirect contribution of 30-40% on the world GDP. The industry produces 20% of the greenhouse gas emissions with cleaner options, like blue hydrogen (produced via natural gas), green hydrogen (produced via electrolysis) and green methane, already starting to penetrate the global markets. Processes like Fischer-Tropsch that still take coal as a feedstock to produce synthetic fuel are an active field of research with hopes to reduce the coal dependence by employing biomass as feedstocks. Catalyst industries have also grown hand in hand with the market for production of sustainable energy solutions. Biofuels, from modern day catalysts, are already available for retail consumption in the western world with hopes to enter the markets for consumers in the rest of the world soon. Electrocatalysis is also a budding research field that hopes to completely stop the usage of fossil fuels for energy generation.
Although, countries with natural resources have been self-sufficient with their energy production (Norway with hydroelectricity, Denmark with solar and wind energy), for the rest of the countries relying on oil or coal, catalysts might just be the alchemist’s gold that saves them from an impending energy crisis whilst addressing climate change concerns.
In our first post, we explored what catalysts are and how they have been instrumental in human development. In our second post, we look at one application specifically, producing energy. For over 100 years catalysts have transformed how we get from A to B, and as will see, will continue to do so by giving us cleaner greener alternative fuels.
By Aditya Sengar, Research Associate in the Department of Bioengineering.
“The Chinese use two brush strokes to write the word crisis. One brush stroke stands for danger; the other for opportunity. In a crisis, be aware of the danger but recognize the opportunity.” The quote by John F. Kennedy, the 35th President of the United States, has stood the times and is quite relevant in context to the catalysis industry today. Set in motion by the two world wars, the industry paved the way for the world to transition from a coal-based economy to crude oil-based economy initially. Now the industry is trying to transition us out of the oil-based economy.
End of the coal era
The world witnessed the dangers of excessive reliance on coal at the end of the 19th century because of rising air pollution by coal burning. London recorded the highest air particulate concentration in the 1890s. The discovery of crude oil in the 1850s was considered the status quo of the future of energy during those times. Crude oil consists of long carbon-chain molecules that need to be broken down to smaller chain molecules like the petroleum products we are more familiar with: petrol, diesel and aviation fuels. Thermal cracking, an industry standard until the 1940s, required burning crude oil at high temperatures to produce the petroleum products. The process was still dirty. Catalytic cracking, developed and refined in the 1930s in the USA, produced higher-octane fuels which served an edge to the Allied forces fighter aircrafts over their German counterparts. The process soon replaced thermal cracking in crude oil refineries. Modern day catalytic cracking involves catalyst in powder form with molecular cage-like structures at nanoscales that hold longer-chain crude oil and provide ion-exchange reactions for an easy breakdown to petroleum products.
1970s energy crisis
In the 1970s, another energy crisis hit the western world. With oil supply saturating in Germany, USA and Venezuela, crude oil price rises rose and led to a decade long economic. The crisis also gave wind to the public’s views on the environmental effects of using coal and crude oil on the planet. The catalyst industry stood up to the task and developed processes for cleaner production of energy using coal, natural gas and oil or sometimes even replacing them.
Clean energy from coal
After the first world war, Germany was producing 14% of its energy supply by synthetic liquid fuel. Liquid fuel has its advantages over coal for being much easier to transport. This is the time before crude oil became the go-to energy resource. The process developed by German chemists Fischer and Tropsch was slowly faded into obscurity because of discovery of vast crude oil reserves across the world making oil a cheap commodity. The 1970s energy crisis made global powers, that were heavily reliant on coal, realize the commercial opportunity provided by the Fischer-Tropsch (FT) process. South Africa now produces 30% of its transport fuel using FT synthesis. The process works with molecular catalysts, called zeolites, with cage-like molecular structures to trap gases like, carbon monoxide and hydrogen[1], and make them react in a series of reactions to produce petroleum products. Modern-day research focuses heavily on reducing carbon dioxide, generated as a by-product of the process, via another catalytic method known as carbon capture and storage.
Biofuels and the struggle to replace crude oil
Biofuels are the alternative to crude oil derived diesel fuels and are produced by a catalytic process where vegetable oils from certain crops, like rapeseed and soybean, react with simple alcohols to form longer carbon chain molecules, the biodiesel. This is not a well-known fact, but the inception of a sustainable energy economy was actually kicked-off by biofuels. It was Nicolaus Otto, the father of the modern internal combustion engine, who first demonstrated an engine running on peanut oil as early as in 1900. Again, huge discoveries of crude oil reserves in the next few decades killed the interest in biofuels. Thanks to the 1970s energy crisis, the industry has since re-emerged and looks stronger than ever now. Although the calorific value (energy in kWh produced per kg of substance) of biodiesel is still 10-20% less than traditional diesel, the cost of production per unit of energy generated is similar. Production of biodiesel still has secondary effects like greenhouse gas emissions by excessive farming and increase in cost of the crops used as feedstock for the biodiesel production. The Paris Agreement of 2016 makes it binding for the signatories to produce 10-15% of their energy requirements by biofuels in the coming decade which is not a very ambitious mission provided the stage the technology is in right now.
Efficient production of electricity from natural gas
Two-thirds of the world’s electricity demand is fulfilled by fossil fuels of which majority is produced inefficiently by coal and natural gas. Furthermore, present-day gridlines to supply electricity to our homes and industries result in heavy energy loss. This results in overall low efficiency (about 33%) of converting primary energy source to usable energy. Enter fuel cells. A fuel cell generates current from a chemical reaction between hydrogen and oxygen over platinum catalyst with 60% efficiency. The oxygen comes from the air. Hydrogen production still requires natural gas (via a process called steam reforming). The produced hydrogen is suitably compressed, stored in a tank, and is replenished at a filling station, like petrol. Over the past 15 years, fuel cell cost has been brought down by 5 times to about $50/kWh (current costs of conventional internal combustion engines are about $30/kW for light-duty vehicles). A major cost of developing a fuel cell goes in the platinum catalyst used as electrode in the cell. Hyundai and Toyota, major automobile companies, are spearheading this initiative to have 31 hydrogen fuel cell powered car models on the road by 2025.
In the final part of this blog series, we will see exciting challenges faced by the catalyst industry and get a glimpse at a possible fossil-free carbon neutral world.
[1] The reactants are more commonly known as syngas, a product of coal gasification. Gasification is a process of reacting coal with a controlled amount of oxygen at high temperatures.