Prof. Invents Way to Trigger Artificial Photosynthesis

Prof. Invents Way to Trigger Artificial Photosynthesis

A chemistry professor has just found a way to trigger the process of photosynthesis in a synthetic material, turning greenhouse gases into clean air and producing energy all at the same time. This process has great potential for creating a technology that could significantly reduce greenhouse gases linked to climate change, while also creating a clean way to produce energy.

“This work is a breakthrough,” said UCF Assistant Professor Fernando Uribe-Romo. “Tailoring materials that will absorb a specific color of light is very difficult from the scientific point of view, but from the societal point of view we are contributing to the development of a technology that can help reduce greenhouse gases.” The findings of his research are published in the Journal of Materials Chemistry.

Uribe-Romo and his team of students 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. Think of it as an artificial photosynthesis process similar to the way plants convert carbon dioxide (CO2) and sunlight into food. But instead of producing food, Uribe-Romo’s method produces
solar fuel.

It’s something scientists around the world have been pursuing for years, but the challenge is finding a way for visible light to trigger the chemical transformation. Ultraviolet rays have enough energy to allow the reaction in common materials such as titanium dioxide, but UVs make up only about 4 percent 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 colors 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 colors of light when incorporated in the MOF. In this case he synchronized it for the color blue.

His team assembled a blue LED photoreactor to test out the hypothesis. 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.

It worked and 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 said.

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