New material may help convert CO2 into fuel using light

Scientists have developed a material that can help convert carbon dioxide into fuel and other energy-rich products using light without generating unwanted byproducts.
The achievement marks a significant step forward in developing technology that can generate fuel, while mitigating levels of a potent greenhouse gas using solar power.
When exposed to visible light, the material, a "spongy" nickel organic crystalline structure, converted carbon dioxide (CO2) into carbon monoxide (CO) gas, which can be further turned into liquid fuels, solvents, and other useful products.
"We show a near 100 per cent selectivity of CO production, with no detection of competing gas products like hydrogen or methane," said Haimei Zheng, scientist at US Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab).

In chemistry, reduction refers to the gain of electrons in a reaction, while oxidation is when an atom loses electrons.
Among the well-known examples of carbon dioxide reduction is in photosynthesis, when plants transfer electrons from water to carbon dioxide while creating carbohydrates and oxygen.

Carbon dioxide reduction needs catalysts to help break the molecule's stable bonds.
Interest in developing catalysts for solar-powered reduction of carbon dioxide to generate fuels has increased with the rapid consumption of fossil fuels over the past century, and with the desire for renewable sources of energy.
Researchers have been particularly keen on eliminating competing chemical reactions in the reduction of carbon dioxide.

"Complete suppression of the competing hydrogen evolution during a photocatalytic CO2-to-CO conversion had not been achieved before our work," said Zheng.
Researchers developed an innovative laser chemical method of creating a metal-organic composite material.
They dissolved nickel precursors in a solution of triethylene glycol and exposed the solution to an unfocused infrared laser, which set off a chain reaction in the solution as the metal absorbed the light.
The resulting reaction formed metal-organic composites that were then separated from the solution.
"When we changed the wavelength of the laser, we would get different composites," said Kaiyang Niu, a materials scientist in Zheng's lab.

"That's how we determined that the reactions were light- activated rather than heat-activated," said Niu.
The study was published in the journal Science Advances.