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Harnessing light for a solar-powered chemical industry



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IMAGE: This is RMIT University Associate Professor Daniel Gomez, holding a disc covered in the nano-enhanced palladium.
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Credit: RMIT University

New technology that harveses sunlight to drive chemical reactions is paving the way for a more sustainable chemical manufacturing industry, one of the world's largest energy users.

RMIT University researchers have developed a nano-enhanced material that can capture an incredible 99% of light and convert it to power chemical reactions.

As well as reducing the environmental impact of chemical manufacturing, innovation could one day be used to deliver technologies like better infrared cameras and solar-powered water desalination.

Published today in ACS Applied Energy Materials, the research addresses the challenge of finding alternative energy sources for chemical production, accounting for about 10% of global energy consumption and 7% of industrial greenhouse gas emissions.

In the US, chemical industry uses more energy than any other industry, accounting for 28% of industrial energy consumption in 2017.

While photo catalysis – the use of light to drive chemical reactions – is growing in the industry, efficiency and cost remain significant obstacles to wider take-up.

Lead researcher Associate Professor Daniel Gomez said the new technology has maximized light absorption to efficiently convert light energy into chemical energy.

"Gomez, an ARC Future Fellow at RMIT's School of Science, said:" Chemical manufacturing is a power hungry industry because traditional catalytic processes require intensive heating and pressure to drive reactions.

"But one of the great challenges in moving to a more sustainable future is that many of the materials that are best for sparking chemical reactions are not responsive enough to light."

"The photo catalyst we have developed can capture 99% of the light across the spectrum, and 100% of specific colors.

"It's scalable and efficient technology that opens new opportunities for the use of solar power – moving from electricity generation to direct converting solar energy into valuable chemicals."

Nano-tech for solar power

The research focused on palladium, an element that is excellent at producing chemical reactions, but usually not very light responsive.

By manipulating the optical properties of palladium nanoparticles, researchers were able to make the material more sensitive to light.

While palladium is rare and expensive, the technique requires just a miniscule amount – 4 nanometers of nano-enhanced palladium is enough to absorb 99% of light and achieve a chemical reaction. An average human hair, for comparison, is 100,000 nanometers thick.

Beyond chemical manufacturing, innovation could be further developed for a range of other potential applications including better night vision technology by producing more light-sensitive and clearer images.

Another potential use is for desalination. The nano-enhanced material could be put into salt water and then exposed to sunlight, producing enough energy to boil and evaporate the water, separating it from the salt.

Gomez, who heads the Polaritonics Lab at RMIT, said the new technology could significantly increase the yield in the emerging photo-catalysis sector, with leading firms currently producing around 30kg of product each day using light as the driving force.

"We all rely on products from the chemical manufacturing industry – from plastics and pharmaceuticals, to fertilizers and materials that produce the colors on digital screens," he said.

"But much like the rest of our economy, it's an industry currently being fueled by carbon.

"Our ultimate goal is to use this technology to harness sunlight efficiently and convert solar energy into chemicals, with the aim of transforming this vital industry into one that is renewable and sustainable."

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The research, with collaborators from CSIRO, the Melbourne Center for Nanofabrication and the University of Melbourne, is published in ACS Applied Energy Materials (DOI: 10.1021 / acsaem.8b01704).

A paper demonstrating similar technology using gold nanoparticles will be published in a forthcoming edition of the journal ACS Photonics.

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