Seaweed as a Superconductor Material

By Benedette Cuffari, M.Sc.Apr 11 2017

Seaweed, or marine macroalgae, is a freely floating plant that is strictly found in seawater, and occasionally brackish water. For marine life purposes, seaweed plays an important role in the maintenance of the ecology of these marine areas, as they often provide a major food source for its habitant herbivorous fish.

Outside of its natural habitat in sea life, seaweed has also had a long history in its presence in several different types of Asian cuisines¹. In fact, seaweed has also recently found a place in Western food culture following an increasing amount of research that has been published regarding its beneficial health effects following its consumption.

Seaweed has also found its useful application in fertilizers, soil conditioners, animal and fish feed, and even for biomass fuel purposes². The demand for seaweed is continually rising as a result of its ability to not only grow at an extraordinarily fast pace, in which it is found to be fully grown in a duration of less than 6 months, but also due to the limitless availability of farm land present in the Earth’s oceans.

Dongjiang Yang, Ph.D. from the Qingdao University in China recently conducted a research initiative that looked at how this multifunctional biological plant could be used as a potential semiconductor. While carbon-based materials, such as graphene, are currently the leading energy storage and conversion products available on the market today, there is a clear challenge present in how to adequately produce large quantities of pure graphene for these purposes³.

In an effort to develop more easily producible substances in a green and efficient manner, the team of Qingdao researchers, in collaboration with scientists from the Los Alamos National Laboratory in the United States, has developed a seaweed-derived material for this purpose.

From the seaweed extract, the research groups developed a porous carbon nanofiber material that was chelated with various metal ions into an “egg-box structure.” Within this egg-box structure, metal ions such as cobalt, copper, iron and nickel, were bound to the alginate, or anionic polysaccharide portion of the extract, to form the functioning nanofiber material⁴.

The remarkable architecture of this seaweed-derived material allowed the researchers to find a reversible capacity measuring at 625 milliampere hours per gram (mAhg -1), which is significantly higher than what is found in traditional graphite anodes used for lithium-ion batteries, whose capacity is only 372 mAhg -1⁴.

The egg-box nanofibers also found a successful performance when applied to commercial platinum-based catalysts that are often used in fuel cells, as they exhibited an enhanced long-term stability in these supercapacitors. Also demonstrated in its application to these fuel-cell technologies, the seaweed nanofiber material demonstrated a high capacitance of 197 Farads per gram, which showed its realistic potential to be applied to zinc-air batteries and future supercapacitors⁴.

While further research must be conducted before any commercialization of seaweed-based superconductors can become a true reality, these scientists are hopeful that this natural way to generate energy could be relevant for a wide variety of future purposes. In addition to possibly replacing the presence of graphite anodes that are used in current lithium-ion batteries, researchers are hopeful that the high capacity of this seaweed material could even be employed in electric cars, as long as the cathode material present within the vehicle is of a comparable quality.

The egg-box structure developed in this study has also inspired similar research initiatives of this nature. In fact, the discussed team of researchers is currently looking at how the combination of red algae-derived carrageenan and iron could create a highly porous carbon aerogel of superior surface area could also be applied for future lithium-sulfur batteries and capacitors⁴.

References

1. "What Are Seaweeds?" The Seaweed Site. Web. http://www.seaweed.ie/algae/seaweeds.php.
2. "Other Uses of Seaweed." FAO Corporate Document Repository. Fishes and Aquaculture Department. Web. http://www.fao.org/docrep/006/y4765e/y4765e0c.htm.
3. "The Challenges Facing Graphene Commercialisation: An Interview with Dr. Ania Servant." AZoNano.com. 20 Mar. 2015. Web. http://www.azonano.com/article.aspx?ArticleID=3950.
4. "Seaweed: From Superfood to Superconductor." ScienceDaily. ScienceDaily, 5 Apr. 2017. Web. https://www.sciencedaily.com/releases/2017/04/170405084036.htm.
5. Image Credit: Shutterstock.com/OliverS

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