New Iron Molecule Could be Useful in Producing Cheaper Solar Energy

For the first time, scientists have been successful in developing an iron molecule that can work both as a photocatalyst to create fuel and in solar cells to generate electricity. The results show that the iron molecule could substitute the more costly and rarer metals currently in use.

The new molecule (Illustration: Nils Rosemann)

Certain photocatalysts and solar cells are based on a technology that involves molecules containing metals, called metal complexes. The task of the metal complexes in this context is to absorb solar rays and exploit their energy. The metals in these molecules pose a huge problem, however, as they are uncommon and costly metals, such as the noble metals ruthenium, iridium, and osmium.

Our results now show that by using advanced molecule design, it is possible to replace the rare metals with iron, which is common in the Earth’s crust and therefore cheap.

Kenneth Wärnmark. Chemistry Professor, Lund University in Sweden.

Along with colleagues, Kenneth Wärnmark was driven for a long time to discover alternatives to the expensive metals. The scientists concentrated on iron which, with its 6% occurrence in the Earth’s crust, is considerably easier to source. The team has created their own iron-based molecules whose potential for use in solar energy applications has been established in earlier studies.

In this new research, the team has gone one step further and created a new iron-based molecule with the ability to trap and utilize the energy of solar light for an adequately long time for it to react with another molecule. The new iron molecule also has the capacity to glow long enough to enable scientists to see iron-based light at room temperature with the naked eye for the first time.

The good result depends on the fact that we have optimised the molecular structure around the iron atom.

Petter Persson, Chemistry Professor, Lund University in Sweden.

The research is currently reported in the journal Science. According to the scientists, the iron molecule in question could be used in new types of photocatalysts for the manufacture of solar fuel, either as methanol from carbon dioxide or as hydrogen through water splitting. Moreover, the new findings pave the way for other potential areas of application for iron molecules, for example, as materials in light diodes (LEDs).

What astonished the Lund scientists is that they reached the good results so fast. In merely over five years, they succeeded in making iron stimulating for photochemical applications, with properties mostly as good as those of the best noble metals.

We believed it would take at least ten years

Kenneth Wärnmark. Chemistry Professor, Lund University in Sweden.

Apart from the scientists from Lund University, colleagues from Uppsala University and the University of Copenhagen were also involved in the partnership.

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