It鈥檚 possible to produce hydrogen to power fuel cells by extracting the gas from seawater, but the electricity required to do it makes the process costly. 麻豆原创 researcher Yang Yang has come up with a new hybrid nanomaterial that harnesses solar energy and uses it to generate hydrogen from seawater more cheaply and efficiently than current materials.
The breakthrough could someday lead to a new source of the clean-burning fuel, ease demand for fossil fuels and boost the economy of Florida, where sunshine and seawater are abundant.
Yang, an assistant professor with joint appointments in the 麻豆原创鈥檚 NanoScience Technology Center and the Department of Materials Science and Engineering, has been working on solar hydrogen splitting for nearly 10 years.
It鈥檚 done using a photocatalyst 鈥� a material that spurs a chemical reaction using energy from light. When he began his research, Yang focused on using solar energy to extract hydrogen from purified water. It鈥檚 a much more difficulty task with seawater; the photocatalysts needed aren鈥檛 durable enough to handle its biomass and corrosive salt.
, Yang and his research team have developed a new catalyst that鈥檚 able to not only harvest a much broader spectrum of light than other materials, but also stand up to the harsh conditions found in seawater.
鈥淲e鈥檝e opened a new window to splitting real water, not just purified water in a lab,鈥� Yang said. 鈥淭his really works well in seawater.鈥�
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. Those nanocavity indentations were 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 to energy. With its new material, Yang鈥檚 team is able to 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 at least twice as efficient as current photocatalysts.
鈥淲e can absorb much more solar energy from the light than the conventional material,鈥� Yang said. 鈥淓ventually, if it is commercialized, it would be good for Florida鈥檚 economy. We have a lot of seawater around Florida and a lot of really good sunshine.鈥�
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鈥檚 team is continuing its research by focusing on the best way to scale up the fabrication, and further improve its performance so it鈥檚 possible to split hydrogen from wastewater.