Researchers at the Yale School of Engineering and Applied Science (New Haven, Connecticut, USA) recently announced the development of a new coating strategy for semiconductors that could provide corrosion protection while improving efficiency and lower the cost of solar fuel production.
Typically, semiconductors that produce solar fuels are illuminated, with specific materials within the semiconductor allowing for the splitting of water into its component parts, hydrogen and oxygen. Known as photocatalytic water splitting, this energy-producing process also makes the materials prone to corrosion.
In response, the research group led by Shu Hu, an assistant professor of chemical and environmental engineering at Yale, has developed a titanium dioxide coating that protects and stabilizes semiconductors, thereby enabling them to generate solar fuel at a large scale.
“With this new coating, we not only improve the stability of the photocatalyst from a few hours to more than 150 hours, but it also improves the solar-hydrogen conversion efficiency above 1.7 percent,” says Tianshuo Zhao, postdoctoral associate and lead author of the study. Zhao adds that this efficiency, which measures how much energy was produced by the device, was a record for solar-to-hydrogen conversion.
Hu says that this energy conversion figure could reach up to 10% in the near future, and eventually even reach 20% efficiency. “If we even get to 10 percent, then the way that we produce solar fuel will completely change,” Hu says. “You see a pathway where the cost of fuels from sunlight is starting to be comparable to the gasoline price or natural gas price. That’s where the tipping point is.”
According to Rito Yanagi, an author of the paper and graduate student at the School of Engineering and Applied Science, the Yale study will be of primary benefit to the field of solar-hydrogen production due to the inefficiency of materials such as oxides and nitrates. At the same time, the stability of semiconductors needs to be improved before it can be viewed as a viable material. To that end, the team focused its efforts on improving the hydrogen half-reaction of the water-splitting reaction.
“The other half-reaction is a little bit more challenging than this half-reaction,” admits Yanagi. “But the basic strategy is the same.”
The results of the Yale study can be found in the Feb. 8 edition of Proceedings of the National Academy of Sciences.
Source: Yale Daily News, https://yaledailynews.com