This shows an artist's conceptualization of the hybrid nanomaterial photocatalyst that can extract hydrogen from seawater. Image: University of Central Florida.One option for obtaining the hydrogen needed to power fuel cells is to extract it from seawater, but the electricity required to do so makes the process costly. A team of researchers led by Yang Yang from the University of Central Florida (UCF) has now come up with a new hybrid nanomaterial that can harness solar energy to generate hydrogen from seawater more cheaply and efficiently than current materials.
This breakthrough could someday lead to a new source of the clean-burning fuel, easing demand for fossil fuels and boosting the economy of Florida, where sunshine and seawater are abundant.
Yang, an assistant professor with joint appointments in UCF's NanoScience Technology Center and the Department of Materials Science and Engineering, has been working on solar hydrogen splitting for nearly 10 years. This requires a photocatalyst – a material that spurs a chemical reaction using the energy from light.
When he began his research, Yang focused on using solar energy to extract hydrogen from purified water. It's a much more difficult task with seawater, though, because conventional photocatalysts aren't durable enough to handle its corrosive salt. As reported in a paper in Energy & Environmental Science, Yang and his team have now developed a new photocatalyst that's not only able to harvest a much broader spectrum of light than other materials, but can also stand up to the harsh conditions found in seawater.
"We've opened a new window to splitting real water, not just purified water in a lab," Yang said. "This really works well in seawater."
Yang developed a method for fabricating a photocatalyst composed of a hybrid material. This involves etching tiny nanocavities onto the surface of an ultrathin film of titanium dioxide, the most common photocatalyst. These nanocavity indentations are then coated with nanoflakes of molybdenum disulfide, a two-dimensional material with the thickness of a single atom.
Typical catalysts are able to convert only a limited bandwidth of light into energy. With their new material, Yang and his team are able to significantly boost the bandwidth of light that can be harvested. By controlling the density of sulfur vacancies within the nanoflakes, they can produce energy from wavelengths of light stretching from ultraviolet-visible to near-infrared, making this nanomaterial at least twice as efficient as current photocatalysts.
"We can absorb much more solar energy from the light than the conventional material," Yang said. "Eventually, if it is commercialized, it would be good for Florida's economy. We have a lot of seawater around Florida and a lot of really good sunshine."
In many situations, producing a chemical fuel from solar energy is a better solution than producing electricity from solar panels, he said. That electricity must be used or stored in batteries, which degrade, while hydrogen gas is easily stored and transported.
Fabricating the catalyst is relatively easy and inexpensive. Yang's team is now continuing its research by focusing on the best way to scale up the fabrication, as well as working on further improving the nanomaterial’s performance so that it can split hydrogen from wastewater.
This story is adapted from material from the University of Central Florida, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.