RMIT says new solar technology could transform chemical manufacturing

Researcher’s from Victoria’s RMIT University have designed a new nano-enhanced material that they claim can capture 98% of light and which can be used to convert light to power chemical reactions, a discovery which could help deliver a more sustainable chemical manufacturing industry – an industry which is one of the planet’s biggest energy users.

According to RMIT, chemical manufacturing accounts for approximately 10% of global energy consumption and generates approximately 7% of industrial greenhouse gas emissions. In the United States, chemical manufacturing uses more energy than any other industry and accounted for 28% of US industrial energy consumption in 2017.

However, we do not often hear of efforts to minimise the consumption or emissions of this industry – given, presumably, its comparatively specialised nature.

While photo catalysis – the use of light to drive chemical reactions – is becoming more common in the chemical manufacturing industry, efficiency and cost remain significant barriers to wider uptake.

“Chemical manufacturing is a power-hungry industry because traditional catalytic processes require intensive heating and pressure to drive reactions,” said Daniel Gomez, an ARC Future Fellow in RMIT’s School of Science and lead investigator.

“But one of the big 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.”

By designing a nano-enhanced material which can so efficiently convert light to power chemical reactions, the RMIT researchers believe they have designed an alternative energy source for chemical manufacturing.

Further, as well as reducing the environmental impact of chemical manufacturing, the researchers believe that their newly-designed nano-material could also be used to deliver technologies such as better infrared cameras and solar-powered desalination.

The development was described in the journal ACS Applied Energy Materialsin an article entitled Directing Energy into a Subwavelength Nonresonant Metasurface across the Visible Spectrum.

The researchers focused their attention on palladium – an element that is known to be excellent at producing chemical reactions but is usually not very responsive to light. Thus, by manipulating the optical properties of palladium nanoparticles, the researchers were able to make it more sensitive to ligh.

Writing in ACS Applied Energy Materials, the authors demonstrated “the design, fabrication, and characterization of a new structure containing a single layer of Pd nanoparticles that absorbs up to >98% of visible light” and show that “the wavelength of absorption is controlled throughout the visible range of the electromagnetic spectrum by modulating the thickness of a supporting metal oxide film.

“We show that the absorbed energy is concentrated in the nanoparticle layer, crucial for energy conversion applications, including photocatalysis and photothermal processes.”

“The photo catalyst we’ve developed can catch 99% of light across the spectrum, and 100% of specific colours,” explained Daniel Gomez.

“It’s scaleable and efficient technology that opens new opportunities for the use of solar power – moving from electricity generation to directly converting solar energy into valuable chemicals.”

Palladium is a rare and expensive material – one of a number of growing issues for the planet – but the technique developed by the RMIT researchers requires only a miniscule amount of the material – specifically, 4 nanometres of nano-enhanced palladium is enough to absorb 98% of light and achieve a chemical reaction.

For comparison, the average human hair is 100,000 nanometres thick.

“We all rely on products of the chemical manufacturing industry – from plastics and medicines, to fertilisers and the materials that produce the colours on digital screens,” said Daniel Gomez. “But much like the rest of our economy, it’s an industry currently fuelled 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’s renewable and sustainable.”

Beyond simply driving chemical reactions, the new nano-enhanced material could be used for a range of applications such as better night vision technology and desalination.

Specifically, the material could help to produce more light-sensitive and clearer images in night vision technology – such as that used in infrared cameras – and used in salty water to help boil and evaporate the water, separating it from the salt.