Sunshine turns carbon dioxide into sustainable fuel

Researchers have transformed carbon dioxide into methanol by shining sunlight on single atoms of copper deposited on a light-activated material, a discovery they said “paves the way for creating new green fuels”.

An international team from the University of Nottingham, University of Birmingham, University of Queensland and University of Ulm in Germany designed the material, made of copper anchored on nanocrystalline carbon nitride.

In photocatalysis, light is shone on a semiconductor material that excites electrons, enabling them to travel through the material to react with CO₂ and water, leading to a variety of useful products, including methanol, which can be used as a green fuel.

Despite recent progress, the researchers said the process has suffered from a lack of efficiency and selectivity. Conventional thermal methods also rely on hydrogen sourced from fossil fuels. “It is important to develop alternative methods based on photo- and electrocatalysis, taking advantage of the sustainable solar energy and abundance of omnipresent water,” a Nottingham announcement said.

Dr Madasamy Thangamuthu from the university, who co-led the research team, said: “It is important that the photocatalyst absorbs light and separates charge carriers with high efficiency. In our approach, we control the material at the nanoscale. We developed a new form of carbon nitride with crystalline nanoscale domains that allow efficient interaction with light as well as sufficient charge separation.”

The researchers devised a process of heating carbon nitride to the required degree of crystallinity, maximising the functional properties of the material for photocatalysis. Using magnetron sputtering, they deposited atomic copper in a solvent-free process, allowing close contact between the semiconductor and metal atoms.

“This invention represents a significant step towards a deep understanding of photocatalytic materials in CO₂ conversion. It opens a pathway for creating highly selective and tuneable catalysts where the desired product could be dialled up by controlling the catalyst at the nanoscale,” the announcement said.

The work was funded by the Engineering and Physical Sciences Research Council (EPSRC).

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