Researchers have designed an "artificial sheet" producing clean gas by photosynthesis

In recent years, progress in sustainable development and renewable energy has been encouraging, but there is still much work to be done to build a less uncertain climate future. In this effort, researchers at the University of Cambridge have developed an "artificial sheet" to produce "clean" synthetic fuel.

The advantage of the proposed solution is the sustainable production of syngas (or synthesis gas), a mixture of hydrogen and carbon monoxide. Currently, syngas is widely used in the production of various fuels, drugs, plastics and fertilizers.

It can be made in different ways, but usually involves the remains of products derived from coal or petroleum-based materials. Thus, the final product is not always carbon neutral. To overcome this problem, the researchers wanted to find a clean and sustainable solution.

A gas production without release of carbon dioxide

The new device, acting like a leaf, is immersed in water and is powered by sunlight. However, it can also work in cloudy weather. It makes it possible to produce a sustainable synthesis gas without releasing carbon dioxide into the air. The study was published in the journal Nature Materials.

" You may not have heard of the synthesis gas itself, but every day you consume products created with this gas, " says chemist Erwin Reisner , lead author of the study, from the University of Cambridge in the United Kingdom.

" Being able to produce it in a sustainable way would be a crucial step in closing the global carbon cycle and establishing a sustainable industry for chemicals and fuels, " he adds.

The new device in full operation. Credits: Virgil Andrei

The artificial leaf imitates plant photosynthesis, combining incoming light, water and carbon dioxide with a catalyst. Operation is provided by two light absorbers (similar to plant molecules that harvest sunlight), combined with a catalyst made from cobalt. At the other end, hydrogen and carbon monoxide are produced, which can then themselves be used to produce syngas.

The selected, state-of-the-art perovskite light absorbers are ultra-efficient: they provide high voltage and high electrical current to fuel the chemical reaction by which carbon dioxide is reduced to carbon monoxide . Compared with light absorbers composed of silicon or dye-sensitive materials, this system is much more efficient.

The researchers also used molecular cobalt catalysts instead of platinum or silver. Cobalt is not only less expensive (because it is more abundant on Earth), but it is also more efficient at producing carbon monoxide than other catalysts.

Although the performance of the system is rather low at the moment, it should be possible to improve it with further research. Scientists announce that it is the unique combination of materials and catalysts that makes their system much more interesting than similar devices in terms of environmental impact and usage framework.

" You are not limited to using this technology only in hot countries, or to keep the process running only during the summer months ," says chemist Virgil Andrei from Cambridge University. " You can use it from dawn to dusk, anywhere in the world ."

Virgil Andrei, holding the artificial leaf that he developed with his team. Credits: Chanon Pornrungrog / Cambridge University / PA Wire

This is of course important in areas of the world where a stable power supply (solar panels or other) is not always guaranteed. And although renewable energy vectors such as wind turbines and photovoltaic panels are becoming more efficient, global energy demand goes far beyond domestic electricity.

Indeed, Reisner says that synthetic fuel production is vital because electricity can currently only supply about 25% of our total global energy demand. In particular, there is a strong demand for liquid fuels for heavy transport, including freight transport (sea and air), all of which require cleaner fuels. This artificial leaf could allow to produce a certain amount.

With respect to this new study, team members reported having confidence in their catalysts and the combination of materials chosen. Over time, synthesis gas may not even be needed as an intermediate step: fuel production could be done directly from carbon dioxide and water.

" What we would like to do next, instead of producing synthesis gas first and then converting it to liquid fuel, is to make the liquid fuel in one step, from carbon dioxide and water, " Reisner concludes.


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