How to Convert Carbon Dioxide (CO2) into Fuels

If the CO2 content of the atmosphere is not to increase any further, carbon dioxide must be converted into something else. However, as CO2 is a very stable molecule, this can only be done with the help of special catalysts. The main problem with such catalysts has so far been their lack of stability: after a certain time, many materials lose their catalytic properties.

At TU Wien (Austria), research is being conducted on a special class of minerals – the perovskites, which have so far been used for solar cells, as anode materials or electronic components rather than for their catalytic properties. Now scientists at TU Wien have succeeded in producing a special perovskite that is excellently suited as a catalyst for converting CO2 into other useful substances, such as synthetic fuels. The new perovskite catalyst is very stable and also relatively cheap, so it would be suitable for industrial use.

We are interested in the so-called reverse water-gas shift reaction,” says Prof. Christoph Rameshan from the Institute of Materials Chemistry at TU Wien. “In this process, carbon dioxide and hydrogen are converted into water and carbon monoxide. You can then process the carbon monoxide further, for example into methanol, other chemical base materials or even into fuel.”

This reaction is not new, but it has not really been implemented on an industrial scale for CO2 utilisation. It takes place at high temperatures, which contributes to the fact that catalysts quickly break down. This is a particular problem when it comes to expensive materials, such as those containing rare metals.

Christoph Rameshan and his team investigated how to tailor a material from the class of perovskites specifically for this reaction, and he was successful: “We tried out a few things and finally came up with a perovskite made of cobalt, iron, calcium and neodymium that has excellent properties,” says Rameshan.

Because of its crystal structure, the perovskite allows certain atoms to migrate through it. For example, during catalysis, cobalt atoms from the inside of the material travel towards the surface and form tiny nanoparticles there, which are then particularly chemically active. At the same time, so-called oxygen vacancies form – positions in the crystal where an oxygen atom should actually sit. It is precisely at these vacant positions that CO2 molecules can dock particularly well, in order to then be dissociated into oxygen and carbon monoxide.

We were able to show that our perovskite is significantly more stable than other catalysts,” says Christoph Rameshan. “It also has the advantage that it can be regenerated: If its catalytic activity does wane after a certain time, you can simply restore it to its original state with the help of oxygen and continue to use it.

Initial assessments show that the catalyst is also economically promising. “It is more expensive than other catalysts, but only by about a factor of three, and it is much more durable,” says Rameshan. “We would now like to try to replace the neodymium with something else, which could reduce the cost even further.“Theoretically, you could use such technologies to get CO2 out of the atmosphere – but to do that you would first have to concentrate the carbon dioxide, and that requires a considerable amount of energy. It is therefore more efficient to first convert CO2 where it is produced in large quantities, such as in industrial plants. “You could simply add an additional reactor to existing plants that currently emit a lot of CO2, in which the CO2 is first converted into CO and then processed further,” says Christoph Rameshan. Instead of harming the climate, such an industrial plant would then generate additional benefits.


Could Deep Sea Mining Fuel The Electric Vehicle Boom?

The world is hungry for resources to power the green transition. As we increasingly look to solar, wind, geothermal and move towards decarbonization, consumption of minerals such as cobalt, lithium and copper, which underpin them, is set to grow markedly. One study by the World Bank estimates that to meet this demand, cobalt production will need to grow by 450% from 2018 to 2050, in pursuit of keeping global average temperature rises below 2°C. The mining of any material can give rise to complex environmental and social impacts. Cobalt, however, has attracted particular attention in recent years over concerns of unsafe working conditions and labour rights abuses associated with its production.

New battery technologies are under development with reduced or zero cobalt content, but it is not yet determined how fast and by how much these technologies and circular economy innovations can decrease overall cobalt demand. Deep-sea mining has the potential to supply cobalt and other metals free from association with such social  strife, and can reduce the raw material cost and carbon footprint of much-needed green technologies.

On the other hand, concerned scientists have highlighted our limited knowledge of the deep-sea and its ecosystems. The potential impact of mining on deep-sea biodiversitydeep-sea habitats and fisheries are still being studied, and some experts have questioned the idea that environmental impacts of mining in the deep-sea can be mitigated in the same way as those on land.

Magnetic Nanoclusters Kill Hard-To-Reach Tumors

Researchers at Oregon State University have developed an improved technique for using magnetic nanoclusters to kill hard-to-reach tumorsMagnetic nanoparticles – tiny pieces of matter as small as one-billionth of a meter – have shown anti-cancer promise for tumors easily accessible by syringe, allowing the particles to be injected directly into the cancerous growth. Once injected into the tumor, the nanoparticles are exposed to an alternating magnetic field, or AMF. This field causes the nanoparticles to reach temperatures in excess of 100 degrees Fahrenheit, which causes the cancer cells to die. But for some cancer types such as prostate cancer, or the ovarian cancer used in the Oregon State study, direct injection is difficult. In those types of cases, a “systemicdelivery method – intravenous injection, or injection into the abdominal cavity – would be easier and more effective.

The challenge for researchers has been finding the right kind of nanoparticles – ones that, when administered systemically in clinically appropriate doses, accumulate in the tumor well enough to allow the AMF to heat cancer cells to death.

Olena Taratula and Oleh Taratula of the OSU College of Pharmacy tackled the problem by developing nanoclusters, multiatom collections of nanoparticles, with enhanced heating efficiency. The nanoclusters are hexagon-shaped iron oxide nanoparticles doped with cobalt and manganese and loaded into biodegradable nanocarriers.

There had been many attempts to develop nanoparticles that could be administered systemically in safe doses and still allow for hot enough temperatures inside the tumor,” said Olena Taratula, associate professor of pharmaceutical sciences. “Our new nanoplatform is a milestone for treating difficult-to-access tumors with magnetic hyperthermia. This is a proof of concept, and the nanoclusters could potentially be optimized for even greater heating efficiency.”

Findings were published in ACS Nano.


How To Kill Deadly Hospital Bacteria

Scientists at Aston University (UK) have discovered a technique similar to medieval stained glass-making that can completely eradicate the deadliest hospital infections within hours.

Using a so-called bioactive phosphate glass containing small amounts of the metallic element cobalt, the researchers were able to achieve a “complete kill” of the deadly bacterial infections E.coli and Candida albicans (a fungal infection associated with surgery), as well as a near-complete kill of Staphylococcus aureus (the drug-resistant form of which is MRSA).


Lead researcher, Dr Richard Martin of Aston University in Birmingham, said the findings had significant implications, offering the possibility of cheap, antimicrobial implants and coatings to combat the most common sources of infections associated with medical care. Avoiding the need for antibiotics, it is also thought the bioactive glass could be effective against drug-resistantsuperbugs’, helping to tackle the growing problem of antimicrobial resistance (AMR).

According to the European Centre for Disease Prevention and Control (ECDC), over four million people in Europe get a healthcare-associated infection (HAI) every year, and around 37,000 die as a direct result of the infection. In its most recent survey of hospital patients, Public Health England found that 6.4% had a healthcare-associated infection.

In the study, published in the journal ACS Biomaterials, the researchers used a centuries-old technique to make glass laced with trace amounts of cobalt in a furnace heated to over 1,000°C, before rapid cooling to prevent crystallisation. These were then ground down into a fine powder and put into contact with bacteria in petri dishes. The glasses contained varying concentrations of cobalt, providing a controlled release of antimicrobial ions as they dissolved. At the highest concentration, the glass completely eradicated E.coli within just six hours, with a “complete kill” also observed for C.albicans within 24 hours. S.aureus levels were reduced by 99% after 24 hours.


Cheap Nano-Catalysts For Better Fuel Cells

Researchers at Daegu Gyeongbuk Institute of Science & Technology (DGIST) in Korea have developed nano-catalysts that can reduce the overall cost of clean energy fuel cells, according to a study published in the Journal of Applied Catalysis B: Environmental.

Polymer electrolyte membrane fuel cells (PEMFCs) transform the chemical energy produced during a reaction between hydrogen fuel and oxygen into electrical energy. While PEMFCs are a promising source of clean energy that is self-contained and mobile – much like the alkaline fuel cells used on the US Space Shuttle – they currently rely on expensive materials. Also, the substances used for catalysing these chemical reactions degrade, raising concerns about reusability and viability.

DGIST energy materials scientist Sangaraju Shanmugam and his team have developed active and durable catalysts for PEMFCs that can reduce the overall manufacturing costs. The catalysts were nitrogen-doped carbon nanorods with ceria and cobalt nanoparticles on their surfaces; essentially carbon nanorods containing nitrogen, cobalt and ceria. Ceria (CeO2), a combination of cerium and oxygen, is a cheap and environmentally friendly semiconducting material that has excellent oxygen reduction abilities.

The fibres were made using a technique known as electrospinning, in which a high voltage is applied to a liquid droplet, forming a charged liquid jet that then dries midflight into uniform, nanosized particles. The researchers’ analyses confirmed that the ceria and cobalt particles were uniformly distributed in the carbon nanorods and that the catalysts showed enhanced electricity-producing capacity.

The ceria-supported cobalt on nitrogen-doped carbon nanorod catalyst was found to be more active and durable than cobalt-only nitrogen-doped carbon nanorods and platinum/carbon. They were explored in two important types of chemical reactions for energy conversion and storage: oxygen reduction and oxygen evolution reactions.

The researchers conclude that ceria could be considered among the most promising materials for use with cobalt on nitrogen-doped carbon nanorods to produce stable catalysts with enhanced electrochemical activity in PEMFCs and related devices.