Yonsei University research team expects drought problems to be solved through the use of eco-friendly technologies, such as solar-powered steam power generation.

Domestic researchers have developed a plasmonic black gold metafilm that absorbs most of the sunlight and collects it at the nanoscale level.

The Plasmonic Black Gold Metafilm is a gold-aluminum oxide nanostructure film that appears black by absorbing broadband sunlight. The Ministry of Science, ICT and Future Planning (Minister Choi Yang-hee) announced that a research team led by Professor Kim Kyung-sik of Yonsei University has developed a high-efficiency metafilm capable of instantaneously generating steam without a separate light-concentrating process.

Low cost, ease of miniaturization or large-area production, and mass production possible

▲ Schematic diagram of the solar steam generation experiment from black gold metafilm.

The research team conducted research on improving solar steam generation efficiency through metal-dielectric nanostructures through the Basic Research Program (Mid-career Researcher Support Program) supported by the Ministry of Science, ICT and Future Planning, and the results were published on December 14 in Nature Communications, a prestigious journal in the field of natural science.
Professor Kim Kyung-sik ( pictured below ) explained the significance of the research, stating, “Metal metafilms are inexpensive and do not require separate complex systems, making them easy to miniaturize or produce on a large scale, and they possess the advantage of enabling mass production.” He added, “The results of this research can be widely utilized as an eco-friendly core technology to improve the efficiency and productivity of solar-powered steam power generation, steam sterilization, and seawater desalination devices, and are expected to contribute to solving the drought problem that has recently become an issue.”

What was the motivation or background for starting this research?

Previously, heat generation due to light absorption was considered a loss, so research was conducted to minimize it. However, it was decided to maximize heat generation and utilize it in other applications, and a structure was developed that could boil water anywhere using sunlight without a complex power supply.

- An introduction to the research development process.

While researching structures for broadband absorption, it was discovered that this could be achieved through the plasmonic nanofocusing phenomenon, and a high absorption rate was obtained by coating gold based on the structure of anodized aluminum nanowires. Afterwards, a porous tape was found and applied to ensure a continuous supply of water necessary for steam generation.

What difficulties or obstacles did you encounter during the research? How did you overcome (resolve) them?

Although there were difficulties in finding a theoretical verification process for developing the black gold film and utilizing it in solar steam generation experiments, a clue to the solution was found through precise simulation verification and collaborative research and discussions with Professor Park Won-jang of the University of Colorado.

- What makes this achievement different?

It absorbs more than 91% of ultra-wideband wavelength light to convert solar energy into thermal energy with an efficiency of up to 57%, and can produce steam quickly and efficiently with minimal heat loss by floating it on water in the form of a thin film.

What are your most important goals and future research plans?

We intend to contribute to resolving the recent drought problem by utilizing the black gold metafilm developed in this study, and to research methods to produce it at a lower cost for industrial application.