August 22, 2008: Stained glass windows that are painted with nanoparticles of gold purify the air when they are lit up by sunlight, a team of Queensland U. of Technology experts have discovered. Associate Professor Zhu Huai Yong, from QUT’s School of Physical and Chemical Sciences, said that glaziers in medieval forges were the first nanotechnologists who produced colors with gold nanoparticles of different sizes.
Professor Zhu said numerous church windows across Europe were decorated with glass colored in gold nanoparticles. “For centuries, people appreciated only the beautiful works of art, and long life of the colors, but little did they realize that these works of art are also, in modern language, photocatalytic air purifier with nanostructured gold catalyst.”
In very small particles, gold becomes very active in sunlight, Zhu explained. “The electromagnetic field of the sunlight can couple with the oscillations of the electrons in the gold particles and creates a resonance.” The magnetic field on the surface of the gold nanoparticles can be enhanced by up to 100×, which breaks apart pollutant molecules in the air, he said.
Energized by the sun, the gold nanoparticles were able to destroy air-borne pollutants like volatile organic chemical (VOCs), which may often come from new furniture, carpets, and paint in good condition. They’re part of what causes that “new” smell as they are slowly released from walls and furniture — “along with methanol and carbon monoxide, are not good for your health, even in small amounts,” Zhu said. The byproduct of purification through gold nanoparticles was carbon dioxide, he said, which was comparatively safe particularly in the small amounts that would be created through this process.
He said the use of gold nanoparticles to drive chemical reactions opened up exciting possibilities for scientific research. “This technology is solar-powered, and is very energy efficient, because only the particles of gold heat up,” he said. “In conventional chemical reactions, you heat up everything, which is a waste of energy.
Zhu said if the technology could be applied to specialty chemicals production at ambient temperature, “it heralds significant changes in the economy and environmental impact of the chemical production.”