While it is possible to produce hydrogen to power fuel cells by extracting the gas from seawater, the electricity required to do it makes the whole process costly. Yang Yang, a UCF researcher, has developed a new hybrid nanomaterial that uses solar energy to generate hydrogen from seawater and is cheaper and more efficient than current materials.
This breakthrough could lead to a new source of clean-burning fuel, easing the demand for fossil fuels and boost the economy of Florida, where sunlight and seawater are abundant.
Yang, an assistant professor with joint appointments in the University of Central Florida’s NanoScience Technology Center and Department of Materials Science and Engineering, has been working on this research and hydrogen splitting for almost 10 years.
This method is done using a photocatalyst, a material that spurs a chemical reaction using energy from light. When Yang began this research, he focused on using solar energy to extract hydrogen from purified water. This is more difficult with seawater; the photocatalysts needed are not durable enough to handle its biomass and corrosive salt.
Yang and his research team developed a new catalyst that is able to harvest a broader spectrum of light than other materials but also stands up to 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 of fabricating a photocatalyst composed of a hybrid material. Tiny nanocavities were chemically etched onto the surface of an ultrathin film of titanium dioxide, the most common photocatalyst. The nanocavity indentations were coated with nanoflakes of molybdenum disulfide, a 2D material with the thickness of a single atom.
Typical catalysts can convert only a limited bandwidth of light to energy. With the new material, Yang’s team can significantly boost the bandwidth of light that can be harvested. By controlling the density of sulfur vacancy within the nanoflakes, they can produce energy from ultraviolet-visible to near-infrared light wavelengths, making it 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."
Producing a chemical fuel from solar energy is a better solution than producing electricity from solar panels in many situations. That electricity must be used or stored in batteries, which degrade, and hydrogen gas is easily stored and transported.
Fabricating the catalyst is relatively easy and inexpensive. Yang’s team is continuing its research by focusing on the best way to scale up the fabrication and further improve the performance so it’s possible to split hydrogen from wastewater.
A paper on this research was published in the journal Energy & Environmental Science.