Is this the invention that fans of solar cells and cleaner renewable energy have all been waiting for? For starters, it was a research from engineers at the University of Illinois at Chicago, with funds from the U.S. Department of Energy and the National Science Foundation, and was published at the journal of Science.
It claims that the team has engineered a potentially game-changing solar cell that efficiently converts atmospheric carbon dioxide directly into usable hydrocarbon fuel, apparently using the free energy provided by the sun. In addition, the team is promising reduction in production cost.
Unlike the solar cells available in the market today–which convert sunlight into electricity and use heavy batteries for storage of energy–this new device somewhat mimics the work of plants. That is to say, it coverts Earth’s available atmospheric carbon dioxide into energy.
In the press release, the team, with senior author Amin Salehi-Khojin, an assistant professor at UIC, claims that their design will solve two crucial problems at once in the solar cell technology. One of which is the removal of carbon from the atmosphere.
NASA, in case you’re wondering, has been talking about it in years. The space agency in a recent report said that Earth’s CO2 levels surpassed the four-hundred PPM–or, parts per million–in 2013. And that’s the first time in recorded history.
Moving forward, the UIC solar cells also promise efficient production of energy-dense fuel, giving the growing economies around the world the energy they need.
Salehi-Khojin explains that their solar cell is not photovoltaic.
“It’s photosynthetic,” he said.
The solar cell that they’ve made also reverse the unsustainable process of energy production, he added, by recycling the atmospheric carbon into fuel using sunlight.
Plants produce fuel in the form of sugar. With the UIC solar cells, its ‘leaves’ deliver syngas, or synthesis gas, which is a mixture of hydrogen gas and carbon monoxide. The so-called syngas can be burned directly, the team claims, or be converted into diesel or other hydrocarbon fuels for industrial energy.
The part of the press release that is worth the underline is the team’s claim that the process of which “would render fossil fuels obsolete.”
The artificial leaf
Chemical reactions that convert CO2 into burnable forms of carbon are called reduction reactions. Salehi-Khojin explained that engineers around the globe have been exploring different catalysts for CO2 reduction, but so far such reactions have been inefficient, with some that rely heavily on expensive and precious metals, like silver.
So they’ve looked for new catalysts and the best of which turned out to be nanoflake tungsten diselenide. First author of the paper and UIC postdoctoral researcher, Mohammad Asadi, said that the catalyst is a thousand times faster than noble-metal catalysts. Plus, it’s twenty times cheaper.
Other inventors have used TMDC–or Transition metal dichalcogenide–catalysts to produce hydrogen by other means, but not for CO2 reduction. The catalyst, the UIC team says, couldn’t survive the reaction.
The UIC solar cell, which they call artificial leaf, consists of two silicon triple-junction photovoltaic cells of eighteen square centimeters to harvest light. It has the tungsten diselenide and ionic liquid co-catalyst system on the cathode side, and on the anode side, it has cobalt oxide in potassium phosphate electrolyte.
When sunlight of one-hundred watts per square meter energizes the artificial leaf, its cathode bubble up hydrogen and carbon monoxide gas. Meanwhile on the anode, hydrogen ions and free oxygen are produced.
The team believes that the artificial leaf is not only for big industries and businesses, but could also produce energy for small-scale projects. They also want space farers that target Mars to use it, and the reason is that the Martian atmosphere is mostly carbon dioxide.
The paper is titled Nanostructured transition metal dichalcogenide electrocatalysts for CO2 reduction in ionic liquid, and it is now accessible on the web via the Science website.