University of California, San Diego electrical engineers are building a forest of tiny nanowire trees in order to cleanly capture solar energy without using fossil fuels and harvest it for hydrogen fuel generation.
Schematic shows the light trapping effect in nanowire arrays. Photons on are bounced between single nanowires and eventually absorbed by them (R). By harvesting more sun light using the vertical nanotree structure, Wang’s team has developed a way to produce more hydrogen fuel efficiently compared to planar counterparts where they are reflected off the surface (L). Credit: Image Credit: Wang Research Group, UC San Diego Jacobs School of Engineering. Originally published in the journal Nanoscale, reproduced by permission of The Royal Society of Chemistry.
Reporting in the journal Nanoscale, the team said nanowires, which are made from abundant natural materials like silicon and zinc oxide, also offer a cheap way to deliver hydrogen fuel on a mass scale.
"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.
The trees' vertical structure and branches are keys to capturing the maximum amount of solar energy, according to Wang. That's because the vertical structure of trees grabs and adsorbs light while flat surfaces simply reflect it, Wang said, adding that it is also similar to retinal photoreceptor cells in the human eye. In images of Earth from space, light reflects off of flat surfaces such as the ocean or deserts, while forests appear darker.
Wang's team has mimicked this structure in their "3D branched nanowire array" which uses a process called photoelectrochemical water-splitting to produce hydrogen gas. Water splitting refers to the process of separating water into oxygen and hydrogen in order to extract hydrogen gas to be used as fuel. This process uses clean energy with no green-house gas byproduct. By comparison, the current conventional way of producing hydrogen relies on electricity from fossil fuels.
"Hydrogen is considered to be clean fuel compared to fossil fuel because there is no carbon emission, but the hydrogen currently used is not generated cleanly," said Ke Sun, a PhD student in electrical engineering who led the project.
By harvesting more sun light using the vertical nanotree structure, Wang's team has developed a way to produce more hydrogen fuel efficiently compared to planar counterparts. Wang is also affiliated with the California Institute of Telecommunications and Information Technology and the Materials Science and Engineering Program at UC San Diego.
The vertical branch structure also maximizes hydrogen gas output, said Sun. For example, on the flat wide surface of a pot of boiling water, bubbles must become large to come to the surface. In the nanotree structure, very small gas bubbles of hydrogen can be extracted much faster. "Moreover, with this structure, we have enhanced, by at least 400,000 times, the surface area for chemical reactions," said Sun.
In the long run, what Wang's team is aiming for is even bigger: artificial photosynthesis. 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 hopes to mimic this process to also capture CO2 from the atmosphere, reducing carbon emissions, and convert it into hydrocarbon fuel.
"We are trying to mimic what the plant does to convert sunlight to energy," said Sun. "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."
The team is also studying alternatives to zinc oxide, which absorbs the sun's ultraviolet light, but has stability issues that affect the lifetime usage of the nanotree structure. Students with the Wang Research Group will be presenting this research on April 12, 2012, at Research Expo, the annual research and networking event of the UC San Diego Jacobs School of Engineering. Register for Research Expo.
Catherine Hockmuth | EurekAlert!
Further information:
http://www.ucsd.edu
Further reports about: > CO2 > Expo 2010 > Ferchau Engineering > Sun > carbon emission > chemical reaction > flat surfaces > fossil fuels > hydrogen fuel > hydrogen gas > nanotrees > solar energy
Industrial Maturity of Electrically Conductive Adhesives for Silicon Solar Cells Demonstrated
25.04.2018 | Fraunhofer-Institut für Solare Energiesysteme ISE
Silicon as a new storage material for the batteries of the future
25.04.2018 | Christian-Albrechts-Universität zu Kiel
At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.
Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...
Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.
Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...
University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.
Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.
Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...
Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.
The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...
Anzeige
Anzeige
Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"
13.04.2018 | Event News
Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018
12.04.2018 | Event News
IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur
09.04.2018 | Event News
Industrial Maturity of Electrically Conductive Adhesives for Silicon Solar Cells Demonstrated
25.04.2018 | Power and Electrical Engineering
Electrode shape improves neurostimulation for small targets
25.04.2018 | Medical Engineering
Silicon as a new storage material for the batteries of the future
25.04.2018 | Power and Electrical Engineering