Solar Energy Conversion Fellows Publish Results from Scialog Collaboration
Eight years after brainstorming the idea for a collaborative project at the second Scialog: Solar Energy Conversion conference, Gordana Dukovic and Sean Elliott have published their results in the prestigious journal Proceedings of the National Academy of Sciences.
The paper describes a system in which semiconductor nanocrystals are coupled to an enzyme to catalyze CO2 reduction.
“Basically, we have demonstrated the ability to use light as a way to stimulate the generation of carbon-carbon bonds in a useful way that takes up carbon dioxide,” said Elliott, a professor of chemistry at Boston University.
Dukovic, an associate professor of chemistry at the University of Colorado Boulder, said that although there is a lot of enthusiasm today for light-harvesting biohybrid devices, the idea was rather high-risk at the time it was proposed.
“Not a lot of work had been done on biohybrids at the time,” she said. “The nanocrystals were pretty well known, but the enzyme was pretty exotic, so we didn’t have a huge reason to suspect that something as complicated as this would work."
“We were lucky the Scialog reviewers were excited about it,” said Elliott. “Scialog really made this project happen.”
Although they had not met in person until the October 2012 Scialog meeting, Elliott said he knew Dukovic’s work.
“At Scialog meetings, you’re looking around the room trying to make contact with people you want to dance with, scientifically, and based on the work Gordana had already published, I hoped we might find a way to collaborate.”
They worked together at the meeting writing a two-page proposal for a Scialog Collaborative Innovation Award, and pitched it the next day at the final session of the meeting, when all the newly formed collaborative teams present their ideas. “It was funded and we got to work pretty soon thereafter,” Dukovic said.
Their work combining a biological catalyst with inorganic nanocrystals to form carbon−carbon bonds via CO2 reduction has led both researchers to other projects and other funding along the way, allowing them to work at the frontiers of science.
“That little bit of funding sparked the collaboration,” Elliott said. “Although it was not an immediate slam dunk, we both knew it was going to be great. You can’t make science move as fast as you would like.”
Dukovic said they might have published sooner, but putting dissimilar materials together and working with exotic, new enzymes took many iterations to get right. They didn’t always understand their results.
“The real challenge in chemistry is catalyzing large molecular transformations,” she said. “In this case, we found the enzyme refusing electrons when it needs them the most.” They were puzzled by why the efficiency of injection of electrons from the nanocrystal to the enzyme was lower when the enzyme bound the substrate that captures CO2 than when the substrate was absent.
In time, Sean’s work on crystal structures with Cathy Drennan of MIT “allowed us to understand the data we got long ago,” said Dukovic. Through those structures, it became clear that the enzyme at the heart of their system changes its shape during the course of the process of CO2 being captured in the form of a molecule called oxo-glutarate. The team will now refine their light harvesting strategy to take that shape-based interplay into account.
“It illustrates how science works,” Dukovic said. “You always have more questions – it’s hard to know if you’ve answered enough of them.”
For Elliott, Scialog funding early in his career was a seed that influenced the scope and trajectory of his lab’s work.
“One of the wonderful things that comes with RCSA funding is that you don’t have to try to get out three papers as soon as possible in order to get more funding,” he said. “We had the idea, believed in the idea, and now that idea is integrated into our research labs. We couldn’t have had the same research trajectory had there been that initial pressure to publish results."
Elliott, whose group researches the connection between biological electron transfer chemistry and function of redox active proteins and enzymes, will now be working with the relatives of these enzymes to see if they provide enhanced behavior for catalysis.
Dukovic, whose research group focuses on fundamental problems in nanoscience and how they impact the application of nanoscale materials to solar energy harvesting, will be following up on the ways that the enzyme presents challenges for the nanocrystals and fine-tuning the materials they use.
“It really has opened a door to a lot of possibilities for further scholarship,” she said. “Scholarship is about incremental success. One thing is clear is that there are more ideas than there is funding or person power to carry them out."
RCSA Senior Program Director Richard Wiener said this team’s high-impact results demonstrate the value of catalyzing research on untested ideas.
"Sometimes collaborations on very out-of-the-box ideas involving fundamental research can take a fairly long time to get to a major outcome," he said. “With many promising years of research ahead of them, Gordana and Sean are poised to accelerate the pace of discovery science needs to help meet the world’s demand for clean, renewable energy.”
