Electrical Engineers are Building a Forest of Nanotrees

Posted on March 8, 2012

Nanotrees from University of California San Diego

University of California, San Diego electrical engineers are building a forest of tiny nanotrees, or nanowire trees. A green tinted electronic microscopic image of the nanoforest (or 3-D branched nanowire array) is pictured above.

The forest of nanowire trees is being built in an attempt to cleanly capture solar energy without using fossil fuels and harvest it for hydrogen fuel generation. The reseachers say nanowires - made from abundant natural materials like silicon and zinc oxide - offer a cheap way to deliver hydrogen fuel on a mass scale. The research was published in the journal Nanoscale.

"This is a clean way to generate clean fuel," said Deli Wang, professor in the Department of Electrical and Computer Engineering at the UC San Diego Jacobs School of Engineering.

Wang says the trees' vertical structure and branches are keys to capturing the maximum amount of solar energy. The vertical structure of trees grabs and adsorbs light while flat surfaces simply reflect it. Wang notes that in images of Earth from space, light reflects off of flat surfaces such as the ocean or deserts, while forests appear darker. Wang says it acts similar to retinal photoreceptor cells in the human eye.

Wang's team is aiming for artificial photosynthesis in the long run.

Ke Sun, a PhD student in electrical engineering who led the project, says, "We are trying to mimic what the plant does to convert sunlight to energy. We are hoping in the near future our 'nanotree' structure can eventually be part of an efficient device that functions like a real tree for photosynthesis."

Photo: Wang Research Group, UC San Diego Jacobs School of Engineering