Composite nanomaterials show promise for solar hydrogen generation

Feb 08, 2010 By Tim Stephens
Graduate students Jennifer Hensel and Gongming Wang tested the performance of composite nanomaterials in PEC cells for hydrogen production. Photo by Yat Li.

(PhysOrg.com) -- A novel strategy for engineering semiconductor materials can boost the performance of water-splitting solar cells for hydrogen production, according to a new study by researchers at the University of California, Santa Cruz.

Using sunlight to split water into hydrogen and oxygen is potentially a clean and sustainable way to generate hydrogen for fuel-cell vehicles. Photovoltaic cells use solar energy to generate electricity, and electricity can be used to split water by . But a more direct and efficient approach is provided by photoelectrochemical (PEC) cells, which use to generate hydrogen inside the cell itself.

The UCSC researchers focused on the semiconductor material used as a light-absorbing in the PEC cell. They combined two techniques--called elemental doping and quantum dot sensitization--that have been used to improve the performance of metal oxide semiconductors in solar cells. These techniques use nanotechnology to manipulate the structure of a material on the scale of billionths of a meter.

Previous work in the laboratory of Jin Zhang, professor of chemistry and biochemistry at UCSC, showed that this combination of techniques has a synergistic effect, markedly enhancing the performance of (see earlier story). In the new study, Zhang teamed up with Yat Li, assistant professor of chemistry and biochemistry, to test the same strategy in a PEC cell.

"Elemental doping and quantum dot sensitization are two different techniques that work well by themselves. We found that we can combine them to get a synergistic effect," Li said. "We not only extended this idea nicely to a photoelectrochemical cell for generation, we also proposed a new model to explain the observed experimental data."

Zhang noted that more theoretical work is needed to fully understand the mechanisms involved. "Understanding the mechanisms will allow us to optimize the effects," he said. "The model we proposed in the first paper was very preliminary, but the new results have helped us refine our model."

The researchers reported their findings in the journal Nano Letters in a paper posted online on January 25. Lead authors of the paper were Jennifer Hensel, a graduate student in Zhang's lab, and Gongming Wang, a graduate student in Li's lab.

The researchers synthesized thin films of nanoparticles, as well as titanium dioxide nanowire arrays vertically aligned in a thin film on a substrate. The titanium dioxide films were doped with nitrogen, and cadmium selenide nanoparticles were used for quantum dot sensitization. The resulting nanostructured composite materials were then used as photoanodes in a PEC cell to compare their performance in carefully controlled experiments.

The results are an important demonstration of the potential to improve the performance of photoelectrochemical cells, as well as photovoltaic , using carefully designed materials, Zhang said. "The key is that combining different approaches in a rational manner can significantly boost performance," he said.

Explore further: Thinnest feasible nano-membrane produced

More information: Paper: pubs.acs.org/doi/abs/10.1021/nl903217w

Related Stories

Nanotechnology to Create Green Hydrogen

Sep 24, 2004

Hydrogen solar greatly increases the efficiency of creating hydrogen from solar panels by using nanotechnology British company Hydrogen Solar has doubled the performance of its technology, which converts light and water directly ...

Nanostructures for hydrogen production and storage

Nov 03, 2005

Incorporating nanostructures may lead to more efficient hydrogen production and storage, according to researchers from the University of Georgia and the University of California, Santa Cruz who have secured $1.35 million ...

Unprecedented efficiency in producing hydrogen from water

Dec 04, 2006

Scientists are reporting a major advance in technology for water photooxidation �using sunlight to produce clean-burning hydrogen fuel from ordinary water. Michael Gratzel and colleagues in Switzerland note that nature ...

Researchers Developing More Powerful Solar Cells

Sep 18, 2006

Sure, Iowa has its share of rainy, snowy and cloudy days. But look out the window. “We have a lot of sunlight,” said Vikram Dalal as sunshine lit up a late-summer morning and the south-facing windows of his office at ...

Recommended for you

Thinnest feasible nano-membrane produced

Apr 17, 2014

A new nano-membrane made out of the 'super material' graphene is extremely light and breathable. Not only can this open the door to a new generation of functional waterproof clothing, but also to ultra-rapid filtration. The ...

Wiring up carbon-based electronics

Apr 17, 2014

Carbon-based nanostructures such as nanotubes, graphene sheets, and nanoribbons are unique building blocks showing versatile nanomechanical and nanoelectronic properties. These materials which are ordered ...

Making 'bucky-balls' in spin-out's sights

Apr 16, 2014

(Phys.org) —A new Oxford spin-out firm is targeting the difficult challenge of manufacturing fullerenes, known as 'bucky-balls' because of their spherical shape, a type of carbon nanomaterial which, like ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

fed_ph
not rated yet Feb 10, 2010
Nice guys, congratulations for your studies;
I wanted to tell you that I wrote to you on this site.
I hope that this truth do not disturb you but give you pleasant.
kind regards.
Federico (Italy)

More news stories

'Exotic' material is like a switch when super thin

(Phys.org) —Ever-shrinking electronic devices could get down to atomic dimensions with the help of transition metal oxides, a class of materials that seems to have it all: superconductivity, magnetoresistance ...

Innovative strategy to facilitate organ repair

A significant breakthrough could revolutionize surgical practice and regenerative medicine. A team led by Ludwik Leibler from the Laboratoire Matière Molle et Chimie (CNRS/ESPCI Paris Tech) and Didier Letourneur ...

Impact glass stores biodata for millions of years

(Phys.org) —Bits of plant life encapsulated in molten glass by asteroid and comet impacts millions of years ago give geologists information about climate and life forms on the ancient Earth. Scientists ...