B.C. researchers discover 'super-black' material that absorbs more than 99% of light

From left, UBC forestry researchers Dengcheng Feng, Kenny Cheng, Philip Evans and Sara Xu. (UBC Forestry/Ally Penders)

Researchers at the University of British Columbia are staring into an abyss of their own making – a new "super-black" material that absorbs almost all visible light that reaches it.

The team stumbled onto the discovery quite by accident, but they already see potential commercial applications on the horizon.

Forestry professor Philip Evans and PhD student Kenny Cheng were experimenting with high-energy plasma etching, trying to make wood more water-repellant by engraving a microscopic texture similar to that of the moisture-shedding lotus leaf.

But when they used the same etching technique on the wood's end grain, everything went dark – extremely dark.

Rather than discarding the wood, they sent a sample to Texas A&M University's department of physics and astronomy, considered the world leader in validating super-black materials, Evans said on the phone from Australia on Thursday.

The Texas scientists confirmed the UBC specimen reflected less than one per cent of visible light, which is the minimum threshold for super-black or ultra-black materials.

"Ultra-black or super-black material can absorb more than 99 per cent of the light that strikes it – significantly more so than normal black paint, which absorbs about 97.5 per cent of light," Evans said.

"They came back to us with measurements that indicated that the material absorbed 99.3 per cent of all light that struck the surface."

The UBC team has now trademarked the discovery, calling the material Nxylon after "Nyx," the Greek goddess of the night, and "xylon," the Greek word for wood.

Unlike other super-black materials, including Vantablack, which is comprised of carbon nanotubes, the UBC discovery is derived from basswood, a natural resource found throughout North America.

"There's some environmental concerns about carbon nanotubes and nanoparticles, in general," Evans said. "What makes this interesting is that it's obviously made from a renewable material."

Super-black materials have promising applications in astronomy, where the darkest possible coatings are required to reduce stray light and improve the clarity of telescopic images, the researchers noted.

The materials are also used to create more efficient solar-power cells, and to adorn luxury goods, like watches and jewelry, in place of expensive gemstones, like onyx, or rare woods, such as ebony and rosewood.

"The wood industry in B.C. is often seen as a sunset industry focused on commodity products," said Evans. "Our research demonstrates its great untapped potential."

Replacing poached woods

The UBC researchers have already created some prototype watches using the etched wood while exploring other potential commercial applications.

The team is also creating a startup company, the Nxylon Corporation of Canada, looking to monetize their discovery in collaboration with jewellers, artists and tech product designers.

Other applications could include the construction of car dashboards, wall cladding for theatres and panels for the interior of aircraft, Evans said.

One of the most surprising discoveries, according to the researchers, is that Nxylon remained black even when covered with a gold coating to make it electrically conductive enough to be studied through an electron microscope. It retained its super-black quality because the colour is not dependent on pigments or dyes, but rather the structure of the material itself.

Evans, who has worked extensively with governments in Canada and the United States to develop methods to detect illegal logging and prevent poached timber from entering the countries, says the material could even help replace dark woods on the black market.

"A lot of these timbers are very black timbers, things like ebony and rosewoods," he said. "So what you want to do is develop substitutes that reduce the demand for those timbers."