solar energy tagged posts

This nanostructured device, about half the size of a postage stamp, uses sunlight to quickly disinfect water. It consists of thin flakes of molybdenum disulfide arranged like walls on a glass surface and topped with a thin layer of copper. Light falling on the walls triggers formation of hydrogen peroxide (H2O2) and other “reactive oxygen species” that kill bacteria. Credit: C. Liu et al., Nature Nanotechnology

In many parts of the world, the only way to make germy water safe is by boiling, which consumes precious fuel, or by putting it out in the sun in a plastic bottle so ultraviolet rays will kill the microbes. But because UV rays carry only 4% of the sun’s total energy, the UV method takes 6 to 48 hours, limiting the amount of water people can disinfect this way.

Now researchers at the...

A new “bionic leaf” system uses solar energy to produce liquid fuel. Credit: Courtesy of Jessica Polka/Silver Lab

New system surpasses efficiency of photosynthesis. Prof Nocera, and Prof Silver of Harvard University, have co-created a system that uses solar energy to split water molecules and hydrogen-eating bacteria to produce liquid fuels. “This is a true artificial photosynthesis system,” Nocera said. “Before, people were using artificial photosynthesis for water-splitting, but this is a true A-to-Z system, and we’ve gone well over the efficiency of photosynthesis in nature.”

While the study shows the system can be used to generate usable fuels, its potential doesn’t end there...

Bathed in simulated sunlight, this photoelectrolysis cell in the lab of Song Jin, a professor of chemistry at the University of Wisconsin-Madison, splits water into hydrogen and oxygen using a catalyst made of the abundant elements cobalt, phosphorus and sulfur. Credit: David Tenenbaum/University of Wisconsin-Madison

Jin’s research team reports a hydrogen-making catalyst containing phosphorus and sulfur – both common elements – and cobalt, a metal that is 1,000 times cheaper than platinum. This is in answer to the major roadblock to “hydrogen economy”, ie the need for platinum or other expensive noble metals in the water-splitting devices. Noble metals are normally used as they resist oxidation and include many of the precious metals, such as platinum, palladium, iridium and gold.

Catalyst...