̽��ֱ�� of Cambridge - Alexander Forse

Electrified charcoal ‘sponge’ can soak up CO2 directly from the air

sc604 — Wed, 05 Jun 2024 15:00:10 +0000

Researchers from the ̽��ֱ�� of Cambridge used a method similar to charging a battery to instead charge activated charcoal, which is often used in household water filters.

By charging the charcoal ‘sponge’ with ions that form reversible bonds with CO2, the researchers found the charged material could successfully capture CO2 directly from the air.

̽��ֱ��charged charcoal sponge is also potentially more energy efficient than current carbon capture approaches, since it requires much lower temperatures to remove the captured CO2 so it can be stored. ̽��ֱ��results are reported in the journal Nature.

“Capturing carbon emissions from the atmosphere is a last resort, but given the scale of the climate emergency, it’s something we need to investigate,” said Dr Alexander Forse from the Yusuf Hamied Department of Chemistry, who led the research. “ ̽��ֱ��first and most urgent thing we’ve got to do is reduce carbon emissions worldwide, but greenhouse gas removal is also thought to be necessary to achieve net zero emissions and limit the worst effects of climate change. Realistically, we’ve got to do everything we can.”

Direct air capture, which uses sponge-like materials to remove carbon dioxide from the atmosphere, is one potential approach for carbon capture, but current approaches are expensive, require high temperatures and the use of natural gas, and lack stability.

“Some promising work has been done on using porous materials for carbon capture from the atmosphere,” said Forse. “We wanted to see if activated charcoal might be an option, since it’s cheap, stable and made at scale.”

Activated charcoal is used in many purification applications, such as water filters, but normally it can’t capture and hold CO2 from the air. Forse and his colleagues proposed that if activated charcoal could be charged, like a battery, it could be a suitable material for carbon capture.

When charging a battery, charged ions are inserted into one of the battery’s electrodes. ̽��ֱ��researchers hypothesised that charging activated charcoal with chemical compounds called hydroxides would make it suitable for carbon capture, since hydroxides form reversible bonds with CO2.

̽��ֱ��team used a battery-like charging process to charge an inexpensive activated charcoal cloth with hydroxide ions. In this process, the cloth essentially acts like an electrode in a battery, and hydroxide ions accumulate in the tiny pores of the charcoal. At the end of the charging process, the charcoal is removed from the “battery”, washed and dried.

Tests of the charged charcoal sponge showed that it could successfully capture CO2 directly from the air, thanks to the bonding mechanism of the hydroxides.

“It’s a new way to make materials, using a battery-like process,” said Forse. “And the rates of CO2 capture are already comparable to incumbent materials. But what’s even more promising is this method could be far less energy-intensive, since we don’t require high temperatures to collect the CO2 and regenerate the charcoal sponge.”

To collect the CO2 from the charcoal so it can be purified and stored, the material is heated to reverse the hydroxide-CO2 bonds. In most materials currently used for CO2 capture from air, the materials need to be heated to temperatures as high as 900°C, often using natural gas. However, the charged charcoal sponges developed by the Cambridge team only require heating to 90-100°C, temperatures that can be achieved using renewable electricity. ̽��ֱ��materials are heated through resistive heating, which essentially heats them from the inside out, making the process faster and less energy-intensive.

̽��ֱ��materials do, however, have limitations that the researchers are now working on. “We are working now to increase the quantity of carbon dioxide that can be captured, and in particular under humid conditions where our performance decreases,” said Forse.

̽��ֱ��researchers say their approach could be useful in fields beyond carbon capture, since the pores in the charcoal and the ions inserted into them can be fine-tuned to capture a range of molecules.

“This approach was a kind of crazy idea we came up with during the Covid-19 lockdowns, so it’s always exciting when these ideas actually work,” said Forse. “This approach opens a door to making all kinds of materials for different applications, in a way that’s simple and energy-efficient.”

A patent has been filed and the research is being commercialised with the support of Cambridge Enterprise, the ̽��ֱ��’s commercialisation arm.

̽��ֱ��research was supported in part by the Leverhulme Trust, the Royal Society, the Engineering and Physical Sciences Research Council (EPSRC), part of UK Research and Innovation (UKRI), and the Centre for Climate Repair at Cambridge.

Reference:
Huaiguang Li et al. ‘Capturing carbon dioxide from air with charged sorbents.’ Nature (2024). DOI: 10.1038/s41586-024-07449-2

Researchers have developed a low-cost, energy-efficient method for making materials that can capture carbon dioxide directly from the air.

̽��ֱ��first and most urgent thing we’ve got to do is reduce carbon emissions worldwide, but greenhouse gas removal is also thought to be necessary to achieve net zero emissions and limit the worst effects of climate change. Realistically, we’ve got to do everything we can

Alex Forse

Sample of activated charcoal used to capture carbon dioxide

̽��ֱ��text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

Yes

Mess is best: disordered structure of battery-like devices improves performance

sc604 — Thu, 18 Apr 2024 18:00:00 +0000

Researchers led by the ̽��ֱ�� of Cambridge used experimental and computer modelling techniques to study the porous carbon electrodes used in supercapacitors. They found that electrodes with a more disordered chemical structure stored far more energy than electrodes with a highly ordered structure.

Supercapacitors are a key technology for the energy transition and could be useful for certain forms of public transport, as well as for managing intermittent solar and wind energy generation, but their adoption has been limited by poor energy density.

̽��ֱ��researchers say their results, reported in the journal Science, represent a breakthrough in the field and could reinvigorate the development of this important net-zero technology.

Like batteries, supercapacitors store energy, but supercapacitors can charge in seconds or a few minutes, while batteries take much longer. Supercapacitors are far more durable than batteries, and can last for millions of charge cycles. However, the low energy density of supercapacitors makes them unsuitable for delivering long-term energy storage or continuous power.

“Supercapacitors are a complementary technology to batteries, rather than a replacement,” said Dr Alex Forse from Cambridge’s Yusuf Hamied Department of Chemistry, who led the research. “Their durability and extremely fast charging capabilities make them useful for a wide range of applications.”

A bus, train or metro powered by supercapacitors, for example, could fully charge in the time it takes to let passengers off and on, providing it with enough power to reach the next stop. This would eliminate the need to install any charging infrastructure along the line. However, before supercapacitors are put into widespread use, their energy storage capacity needs to be improved.

While a battery uses chemical reactions to store and release charge, a supercapacitor relies on the movement of charged molecules between porous carbon electrodes, which have a highly disordered structure. “Think of a sheet of graphene, which has a highly ordered chemical structure,” said Forse. “If you scrunch up that sheet of graphene into a ball, you have a disordered mess, which is sort of like the electrode in a supercapacitor.”

Because of the inherent messiness of the electrodes, it’s been difficult for scientists to study them and determine which parameters are the most important when attempting to improve performance. This lack of clear consensus has led to the field getting a bit stuck.

Many scientists have thought that the size of the tiny holes, or nanopores, in the carbon electrodes was the key to improved energy capacity. However, the Cambridge team analysed a series of commercially available nanoporous carbon electrodes and found there was no link between pore size and storage capacity.

Forse and his colleagues took a new approach and used nuclear magnetic resonance (NMR) spectroscopy – a sort of ‘MRI’ for batteries – to study the electrode materials. They found that the messiness of the materials – long thought to be a hindrance – was the key to their success.

“Using NMR spectroscopy, we found that energy storage capacity correlates with how disordered the materials are – the more disordered materials can store more energy,” said first author Xinyu Liu, a PhD candidate co-supervised by Forse and Professor Dame Clare Grey. “Messiness is hard to measure – it’s only possible thanks to new NMR and simulation techniques, which is why messiness is a characteristic that’s been overlooked in this field.”

When analysing the electrode materials with NMR spectroscopy, a spectrum with different peaks and valleys is produced. ̽��ֱ��position of the peak indicates how ordered or disordered the carbon is. “It wasn’t our plan to look for this, it was a big surprise,” said Forse. “When we plotted the position of the peak against energy capacity, a striking correlation came through – the most disordered materials had a capacity almost double that of the most ordered materials.”

So why is mess good? Forse says that’s the next thing the team is working on. More disordered carbons store ions more efficiently in their nanopores, and the team hope to use these results to design better supercapacitors. ̽��ֱ��messiness of the materials is determined at the point they are synthesised.

“We want to look at new ways of making these materials, to see how far messiness can take you in terms of improving energy storage,” said Forse. “It could be a turning point for a field that’s been stuck for a little while. Clare and I started working on this topic over a decade ago, and it’s exciting to see a lot of our previous fundamental work now having a clear application.”

̽��ֱ��research was supported in part by the Cambridge Trusts, the European Research Council, and UK Research and Innovation (UKRI).

Reference:
Xinyu Liu et al. ‘Structural disorder determines capacitance in nanoporous carbons.’ Science (2024). DOI: 10.1126/science.adn6242

For more information on energy-related research in Cambridge, please visit the Energy IRC, which brings together Cambridge’s research knowledge and expertise, in collaboration with global partners, to create solutions for a sustainable and resilient energy landscape for generations to come.

̽��ֱ��energy density of supercapacitors – battery-like devices that can charge in seconds or a few minutes – can be improved by increasing the ‘messiness’ of their internal structure.

This could be a turning point for a field that’s been stuck for a little while.

Alex Forse

Nathan Pitt

Left to right: Clare Grey, Xinyu Liu, Alex Forse

Yes

Low-cost battery-like device absorbs CO2 emissions while it charges

cr696 — Thu, 19 May 2022 14:50:54 +0000

̽��ֱ��supercapacitor device, which is similar to a rechargeable battery, is the size of a two-pence coin, and is made in part from sustainable materials including coconut shells and seawater.

Designed by researchers from the ̽��ֱ�� of Cambridge, the supercapacitor could help power carbon capture and storage technologies at much lower cost. Around 35 billion tonnes of CO2 are released into the atmosphere per year and solutions are urgently needed to eliminate these emissions and address the climate crisis. ̽��ֱ��most advanced carbon capture technologies currently require large amounts of energy and are expensive.

̽��ֱ��supercapacitor consists of two electrodes of positive and negative charge. In work led by Trevor Binford while completing his Master’s degree at Cambridge, the team tried alternating from a negative to a positive voltage to extend the charging time from previous experiments. This improved the supercapacitor’s ability to capture carbon.

“We found that that by slowly alternating the current between the plates we can capture double the amount of CO2 than before,” said Dr Alexander Forse from Cambridge’s Yusuf Hamied Department of Chemistry, who led the research.

“ ̽��ֱ��charging-discharging process of our supercapacitor potentially uses less energy than the amine heating process used in industry now,” said Forse. “Our next questions will involve investigating the precise mechanisms of CO2 capture and improving them. Then it will be a question of scaling up.”

̽��ֱ��results are reported in the journal Nanoscale.

A supercapacitor is similar to a rechargeable battery but the main difference is in how the two devices store charge. A battery uses chemical reactions to store and release charge, whereas a supercapacitor does not rely on chemical reactions. Instead, it relies on the movement of electrons between electrodes, so it takes longer to degrade and has a longer lifespan.

“ ̽��ֱ��trade-off is that supercapacitors can’t store as much charge as batteries, but for something like carbon capture we would prioritise durability,” said co-author Grace Mapstone. “ ̽��ֱ��best part is that the materials used to make supercapacitors are cheap and abundant. ̽��ֱ��electrodes are made of carbon, which comes from waste coconut shells.

“We want to use materials that are inert, that don’t harm environments, and that we need to dispose of less frequently. For example, the CO2 dissolves into a water-based electrolyte which is basically seawater.”

However, this supercapacitor does not absorb CO2 spontaneously: it must be charging to draw in CO2. When the electrodes become charged, the negative plate draws in the CO2 gas, while ignoring other emissions, such as oxygen, nitrogen and water, which don’t contribute to climate change. Using this method, the supercapacitor both captures carbon and stores energy.

Co-author Dr Israel Temprano contributed to the project by developing a gas analysis technique for the device. ̽��ֱ��technique uses a pressure sensor that responds to changes in gas adsorption in the electrochemical device. ̽��ֱ��results from Temprano’s contribution help narrow down the precise mechanism at play inside the supercapacitor when CO2 is absorbed and released. Understanding these mechanisms, the possible losses, and the routes of degradation are all essential before the supercapacitor can be scaled up.

“This field of research is very new so the precise mechanism working inside the supercapacitor still isn’t known,” said Temprano.

̽��ֱ��research was funded by a Future Leaders Fellowship to Dr Forse, a UK Research and Innovation scheme developing the next wave of world-class research and innovation.

Reference:
Trevor B Binford, Grace Mapstone, Israel Temprano, and Alexander C Forse. 'Enhancing the capacity of supercapacitive swing adsorption CO2 capture by tuning charging protocols.' Nanoscale (2022). DOI: 10.1039/D2NR00748G

Researchers have developed a low-cost device that can selectively capture carbon dioxide gas while it charges. Then, when it discharges, the CO2 can be released in a controlled way and collected to be reused or disposed of responsibly.

We found that that by slowly alternating the current between the plates we can capture double the amount of CO2 than before

Alexander Forse

Gabriella Bocchetti

Co-authors Israel Temprano and Grace Mapstone

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

Yes