November 26, 2018
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The sun teases us every day, emitting enough energy in sunlight in one hour to power human use for nearly a year. And yet effectively harnessing just a tiny fraction of that energy to create clean and renewable fuel eludes the scientific community 60 years after the advent of photovoltaics, the solar cells that convert sunlight into electricity.
No one is more aware of this phenomenon than the scientist who strives to help establish sunlight as an economically viable and sustainable source of energy on a grand scale. Three chemistry faculty members at Kenyon fit that description, each contributing a specific answer to the many vexing questions associated with solar-energy research.
How, for example, can we use solar power to split water molecules, unleashing hydrogen as an abundant, renewable, and perfectly clean fuel source? Professor Scott Cummings is studying whether platinum complexes can absorb light and transfer an electron to help drive the reaction required to split water.
And what about materials? For half a century, solar-cell technology has revolved around the use of silicon, an abundant earth element that is limited in long-term usefulness because of its high expense and heavy weight.
Associate Professor Simon Garcia specializes in refining the crystal forms of compounds – particularly zinc oxide – that, if precisely shaped by chemical reactions, could constitute the next generation of solar cells. And Yutan Getzler, also an associate professor, seeks to develop light-harvesting, plastics-based solar cells that could provide more durability than silicon and potentially lower manufacturing costs.
The three are driven by an assortment of motivations: a wish to attach deep meaning to their research program by addressing a significant global problem, providing research opportunities for students, and producing materials for devices that, to date, are only imagined in science fiction.
In the case of combining sunlight and water to release hydrogen as fuel, the inspiration is right outside the window.
“There are embedded in this simple idea a long list of fundamental chemistry questions,” Cummings said. “And the leaf is doing this exact chemistry right before our eyes: absorbing photons, splitting water, and making oxygen that we breathe. And rather than making hydrogen, the leaf combines the rest to make carbohydrate molecules.” Why focus on fuel instead of electricity? It’s all about replacing the dwindling supply of fossil fuels that foul the atmosphere when burned. Also, Cummings noted, “The most obvious issue is that when the sun goes down, the electricity stops running.”
The sun powers hundreds of thousands of buildings and homes around the world, most commonly through the cells that convert sunlight into electricity. (Solar energy also is collected to heat fluids, creating steam that powers generators to produce electricity.) The production of solar energy is by no means a failed effort – but it is ripe for improvement. This is where the materials work led by Garcia and Getzler comes in, with Garcia emphasizing compound shapes and Getzler focusing on lightweight polymer products.
Garcia has found that, in its crystal form, zinc oxide grows in two different shapes that have potential applications for solar cells and light-emitting diodes. The trick to obtaining these shapes is developing a chemical mixture that will make the crystals grow into these desired structures – they are too small to manipulate in any other way.
“I see myself as potentially expanding the tool kit of the engineer who is trying to make different kinds of solar cells for different purposes,” he said. “The fundamental research is about shape, so the applications aren’t just for solar energy. They’re also for high-efficiency, low-cost lighting and electronic devices that can detect or create vibrations.”
Chemists are exploring new materials because making the most efficient silicon solar cells is an energy-intensive process. Getzler, a longtime specialist in biodegradable plastics that have commercialization potential for other uses, is modifying his research program so his work addresses climate change – specifically by designing plastics that could function as solar cells.
“There is no perfect system. So the question is, can we develop enough different kinds of systems so that when we Venn-diagram them out, there is enough overlap to balance the advantages and imperfections against each other,” he said. “We have to fight the good fight. I think at an undergraduate liberal arts institution, one of the most important things I can do is telegraph the problems I believe are important.”
This subject is not reserved to students in the sciences. For several years, Cummings has taught a Solar Energy course he designed for students outside the sciences. In class, discussions cover the basics of chemistry as well as such topics as politics, economics and entrepreneurship.
Kenyon students in the sciences, meanwhile, perform much of the labor generated by faculty ideas, learning not just lab techniques but also the crux of the research endeavor – that failure can be expected, according to Getzler, but is a valuable part of learning. And that even seemingly small pieces of solutions to the world’s most complex problems are important contributions, especially if their pursuit is intellectually and morally satisfying.
“Students aren’t going to solve these problems as undergraduates,” Garcia said. “They’re going to go on and either start a business, go to graduate school, or start some sort of advocacy. That is where their experience in the laboratory, with reading, with exploring research questions, is going to be what helps them. And the wider that experience is, the better.”
Students participating in the professors’ lab groups are: with Cummings, Josh Jacobvitz ’15, New York City and Chris Rogers ’15, Honolulu; with Garcia, Stephanie Cordonnier ’15, Bradford, Ohio, Khalil Chatman ’16, Brandon, Fla., and Dan Druffel ’14, Cincinnati; and with Getzler, Harry Hurley ’14, Maplewood, N.J., Wesley Manz ’15, Eau Claire, Wisc., and Shannon Wright ’16, Penfield, N.Y.