Towards Converting CO2 to Fuel: A Computer-Aided Experimental Discovery of Novel CO2 Reduction Catalysts.
One of the holy grails of chemistry, says theoretical chemist Mu-Hyun "Mookie" Baik, is to answer this simple question: "How can we activate carbon dioxide?" His recent Scialog grant will finance his efforts to convince the aloof CO2 molecule to take part in chemical reactions. "When you think about it," he says, "the reason why CO2 is such a problem is that it's incredibly stable and inert. It's essentially the final product of combustion, so it sticks around forever. And water is the same way. Water is also the final product of combustion." Baik creates complex computer models that simulate chemical reactions; his expertise lies in using those computer models to predict new chemistry - like "activating" carbon dioxide. Ultimately, he says, we should be able to burn it as a fuel. "Essentially, what we'd be doing is attempting to use this carbon-based fuel as a storage device for solar energy. And, because we would be using CO2 from our environment, over all there would be zero impact on the environment." To complicate this already difficult challenge, Baik wants to find a process that will activate CO2 at room temperatures. It's a project that falls well within the parameters of what's called high-risk/high-reward research, an approach to science that increasing numbers of scientists and policy thinkers say is essential if we hope to solve some of the big, complicated problems looming over our future global prosperity and security. The growing need for clean, renewable energy is one of those problems. "The real high-risk approach here," Baik says of his project, although somewhat tongue in cheek, "is that I proposed to carry out my own experiments. Basically, I just gathered some of my bravest students together and said, you know, let's do this. Let's go and bother some of my colleagues and ask them how to do this. Have them show us how to do it, and we'll just do it." Indeed, the panel of distinguished scientists who reviewed the Scialog proposals eventually funded by Research Corporation for Science Advancement remarked that it was fairly unusual for a theorist like Baik to want to roll up his sleeves and tackle the nitty-gritty procedures of the laboratory bench. However, as Scialog Program Officer Richard Wiener points out, "Dr. Baik's attempt to achieve the catalytic transformation of CO2 in a way counter to current thinking as the truly high risk part of the proposal. The fact that a theorist also wants to do the experiment is very interesting, but the actual science itself is what is the highest risk." Baik says he wants to perform the experiments, rather than just design them, because he's aiming to overcome a "bottleneck" inherent in the process of taking a theory into the lab. "The bottleneck is the communication," he says. "When these two parts of the same project are in two different brains, we always lose information. If we want to solve the problems that lie ahead of us, we need a new kind of a scientist who can do experiments and conceptualize using some of the new technology that we have—computer models now are so powerful that if I put this into hands of somebody who also has the experimental intuition, I feel we can leverage this beyond what ordinary collaborations allow us to do. " Ultimately, though, intellectual excitement seems to be Baik's main motivation. "I have a proposal for constructing what promises to be the world's most efficient CO2 reduction catalyst," he says. "It will allow me to do chemical reactions with CO2." In chemistry, apparently, the discovery of new catalysts has been a bit of a craps shoot. "We've had to rely on the Goddess Fortuna helping us," Baik says. "That's because we don't really understand how these things work, and we just go ahead and try a whole bunch of things in the hope that eventually we'll discover something new." Baik's approach has been to go back to a CO2 catalyst that has been known for some time, although it's so poor at the task as to be "not technologically exploitable;" and to examine and model it on the computer in new ways. He adds: "I've done a few of these experiments already, and they're very promising. They clearly identify that the way we've been thinking of CO2 reduction is not correct. So I have a new proposal of how this actually works." The catalyst in question is based on ruthenium, a rare metal with a relatively high potential for activating CO2 - which isn't saying much because, as Baik has pointed out, the efficiencies are really low. "When we did our computer simulation," Baik says," we found that part of the molecule was just sitting there, not doing anything. And, in fact, the computer simulation said that if you remove that part of the molecule, the reaction becomes even better, because this catalyst essentially has an intrinsic flaw that no one recognized. So we removed this part of the catalyst that people thought to be important and we exposed the fragment, this new simplified catalyst, to the same conditions, and we saw a significant improvement in the catalytic behavior"—proof, he says, that the computer model is credible, and he adds that it also suggests a promising new pathway to the catalytic transformation of CO2. Assuming his approach works - at this point there are no real guarantees, of course-Baik and his colleagues eventually will need to collaborate with engineers and other scientists who know how to "deliver the energy," as he puts it. That's why he says he's looking forward to the Scialog conference, because "once we have the concept and a proof-of -concept type of experiment, I need to seek the help of people who can actually build support systems that will house the core reactive molecule that I'll be designing. Looking through the list of Scialog awardees, I'm finding people who are working on solid-state chemistry. That's exciting." Baik says many researchers with potentially breakthrough ideas have been hobbled in recent years by tight money among federal funding agencies, a situation which has led to the tendency among scientists "to be conventional and very conservative. I love and cherish the review process that proposals and research ideas must go through, but all it takes is one person saying, ‘This is nonsense, and I don't believe a word of it,' and you're out. And so you'll never get the funding for a new idea." He adds that he's grateful to Research Corporation for allowing him to use money from a non-Scialog grant the Foundation had given him a few years ago to get started in this work. "I talked to some of the people at Research Corporation, and they said, ‘This is exactly why we gave you that money, to try out something that's crazy and that may essentially work.' And, as it happens, a couple of weeks ago the National Science Foundation told me they've decided to fund this work as well." So the high-risk side of Mookie Baik's equation is covered. Now it's up to him to produce the high rewards, or at least teach us some important new lessons about the catalytic transformation of CO2.