Hydrogen has been examined as a potential clean and renewable energy source that could be produced through water splitting. For hydrogen to truly be an environmentally-friendly energy source, researchers must develop a way to produce it on a large scale, without using fossil fuels in the process. One potential way to do this is by leveraging solar energy to split water through “artificial photosynthesis” using photocatalytic materials. Researchers at the Nagoya Institute of Technology recently sought to improve the efficiency and durability of solar-powered water splitting cells by using two promising photocatalysts in tandem.
The researchers used titanium oxide (TiO2) and p-type cubic SiC (3C-SiC) crystals in a tandem structure to create a photoelectrochemical water splitting cell. The semitransparent TiO2 operates as a photoanode and 3D-SiC as a photocathode, with each material absorbing solar energy at different frequency bands. This structure allowed more incoming light to excite charge carriers and generate the necessary currents for water splitting, resulting in a relatively high solar-to-hydrogen (STH) conversion efficiency. The tandem structure was also found to be more durable than many existing photoelectrodes and photocatalysts. The research was published in Solar Energy Materials and Solar Cells.
“The maximum applied-bias photon-to-current efficiency measured was 0.74%. This value, coupled with the observed durability of about 100 days, puts our water splitting system among the best currently available,” said Masashi Kato, one of the study authors.
Further research is needed to continue improving the efficiency and durability of the water splitting system, until it could eventually be used for widespread clean energy production. Kato said he hopes the team’s contribution will accelerate the development of artificial photosynthesis technologies and lead to more sustainable societies.
Photo: The use of a semitransparent TiO2 photoanode allows the SiC photocathode to make use of the transmitted light. Using photocatalysts with different energy gaps results in increased conversion efficiency. Credit: Masashi Kato from Nagoya Institute of Technology