Artificial photosynthesis turns carbon dioxide into clean air

Scientists have found a way to trigger artificial photosynthesis, turning greenhouse gases such as carbon dioxide into clean air and producing energy at the same time.
"This work is a breakthrough," said Fernando Uribe-Romo, Assistant Professor at University of Central Florida (UCF) in the US.
The team created a way to trigger a chemical reaction in a synthetic material called metal-organic frameworks (MOF) that breaks down carbon dioxide into harmless organic materials.
The process is similar to photosynthesis in which plants convert carbon dioxide (CO2) and sunlight into food. However, instead of producing food, the new method produces solar fuel.

Ultraviolet (UV) rays have enough energy to allow the reaction in common materials such as titanium dioxide, but UVs make up only about 4 per cent of the light Earth receives from the sun.
The visible range - the violet to red wavelengths - represent the majority of the sun's rays, but there are few materials that pick up these light colours to create the chemical reaction that transforms CO2 into fuel.

Researchers have tried it with a variety of materials, but the ones that can absorb visible light tend to be rare and expensive materials such as platinum, rhenium and iridium that make the process cost-prohibitive.

Uribe-Romo used titanium, a common nontoxic metal, and added organic molecules that act as light-harvesting antennae to see if that configuration would work.
The light harvesting antenna molecules, called N-alkyl-2 -aminoterephthalates, can be designed to absorb specific colours of light when incorporated in the MOF. In this case he synchronised it for the colour blue.
Measured amounts of carbon dioxide were slowly fed into the photoreactor - a glowing blue cylinder that looks like a tanning bed - to see if the reaction would occur.
The glowing blue light came from strips of LED lights inside the chamber of the cylinder and mimic the sun's blue wavelength.

The chemical reaction transformed the CO2 into two reduced forms of carbon, formate and formamides (two kinds of solar fuel) and in the process cleaning the air.
"The goal is to continue to fine-tune the approach so we can create greater amounts of reduced carbon so it is more efficient," Uribe-Romo added.
The findings were published in the Journal of Materials Chemistry A.