A meteorite could help with cheap storing of renewable energy
A fragment of the Gibeon meteorite © K. Sivula/EPFL
The prehistoric Gibeon meteorite has proven to be an ideal, natural catalyst for water-oxidation reactions energy storage, EPFL scientists find.
One of the key factors in creating sustainable sources of renewable and clean energy is the conversion of electricity into chemical energy stored in molecular bonds. To do this efficiently, we need electrocatalyst materials that are robust, efficient, and cheap. EPFL scientists now have shown that tons of such materials already exist in nature — in the form of the Gibeon meteorite that crashed into Namibia in prehistoric times. The study is published in Energy & Environmental Science.
The Gibeon meteorite actually refers to thousands of meteorite fragments that are strewn across what is now the Namaqualand region of Namibia. Discovered in 1838, the fragments are dispersed across an area 275 km long and 100 km wide. The meteorite is 90% iron and 8% nickel, and also contains some cobalt and phosphorus.
A team of chemists from EPFL’s Institute of Chemistry and Chemical Engineering (ISIC), led by Kevin Sivula, have studied the Gibeon meteorite as a catalyst for the water-splitting reaction. This reaction breaks water into oxygen and hydrogen gas when an electric current passes through electrodes generating hydrogen fuel, which can be used to store solar or other non-fossil-fuel energy. Like all chemical reactions, the efficiency of the water-oxidation reaction depends largely on the presence of a catalyst material — in this case, an electrocatalyst.
Given that the water-oxidation reaction is generally still too inefficient and expensive compared to using natural (fossil) gas, there is a hunt for cheap and efficient electrocatalysts. As such, materials containing inexpensive iron as a main ingredient have come to the fore because they offer a trade-off between cost and activity. However, the impurities in the iron are known to be the key to high electrocatalytic activity. That’s where the meteorite comes in: these naturally occurring materials have a characteristic concentration of impurities of nickel and cobalt, which turn out to be ideal for electrocatalysis.
The EPFL scientists cut samples of the Gibeon meteorite into thin slices, polished them to a mirror-like finish and soldered them to copper wires to build electrodes. They then ran a series of tests to evaluate their performance in the water-oxidation reaction.
The iron-based, extraterrestrial electrodes showed “state-of-the-art performance”, edging out the best man-made materials. The structure and composition of the Gibeon meteorite is a big hint as to what compositions should be further explored and optimized for large-scale use in cheap and efficient electrolyzer devices.
This work involved a collaboration between Kevin Sivula’s and Paul Dyson’s laboratories and was funded by the Swiss Competence Centers for Energy Research. It also involved contributions from EPFL’s Institute of Physics.
Reference
Florian Le Formal, Néstor Guijarro, Wiktor S. Bourée, Aswin Gopakumar, Mathieu S. Prévot, Albert Daubry, Loris Lombardo, Charlotte Sornay, Julie Voit, Arnaud Magrez, Paul J. Dysona, Kevin Sivula. A Gibeon meteorite yields a high-performance water oxidation electrocatalyst. Energy & Environmental Science 12 September 2016. DOI: 10.1039/C6EE02375D