A breakthrough at the UC San Diego School of Engineering could offer an environmentally friendly and less expensive way to produce hydrogen—a carbon-free fuel—by taking advantage of a novel tree-like nanostructure. The vertical branch structure, or “nanotree,” is used to maximize solar energy capture and hydrogen gas output.
“With this structure, we have enhanced, by at least 400,000 times, the surface area for chemical reactions,” said Ke Sun, a Ph.D. student in electrical engineering who led the project.
Reporting in the journal Nanoscale, the team said they are building a forest of tiny nanowire trees in order to cleanly capture solar energy in a way that mimics the way trees absorb energy.
Like the famous work by Daniel Nocera, artificial photosynthesis is the inspiration for the UC San Diego Jacobs School of Engineering team working under Deli Wang, professor in the Department of Electrical and Computer Engineering. (We’ve also seen MIT’s Andreas Mershin devise an “electric nanoforest” in the quest for cheap solar power.)
In photosynthesis, as plants absorb sunlight they also collect carbon dioxide (CO2) and water from the atmosphere to create carbohydrates to fuel their own growth.
Wang’s team also hopes to mimic this natural photosynthesis process to capture CO2 from the atmosphere, reducing carbon emissions, and convert it into hydrocarbon fuel.
Most of this promising hydrogen research is focused on substituting clean energy with no greenhouse gas byproduct for today’s fossil-fueled hydrogen splitting. Wang’s “3D branched nanowire array” uses a process for separating water into oxygen and hydrogen called photoelectrochemical water-splitting that uses sunlight.