December 17, 2018 – Sheng Dai, the most prolific author ever at the Department of Energy’s Oak Ridge National Laboratory, had no intention of pursuing a career in science as a young man; he wanted to paint instead. But he couldn’t help noticing that the stones artists carved with their initials and used to stamp their creations often contained more than one color, and it sparked his curiosity.
“The most valuable stones had a red vein running through them,” Dai said. “I was intrigued by this. What caused that red color? Could you change the color? Could you convert a colorless stone into one with color?” Pursuing those answers stoked an interest in chemistry that eventually grew into a career. “My parents were relieved,” he said. “They had been worried that I couldn’t secure a living by painting.”
Today, Dai is world-renowned for innovating chemical separations, nanomaterials synthesis, and catalytic interfaces for energy applications. His more than 700 peer-reviewed publications have netted 36,677 total citations, earning an exceptional h-index (reflecting productivity and impact) of 96. He also holds a total of 51 patents.
Dai is leader of the Nanomaterials Chemistry Group in the Chemical Sciences Division and a Corporate Fellow researcher at ORNL, who also holds a joint faculty appointment in the Department of Chemistry at the University of Tennessee, Knoxville. He is director of the Fluid Interface Reactions, Structures and Transport Center, or FIRST, a DOE Energy Frontier Research Center based at ORNL that focuses on an atomistic understanding of electrolytes and electron transport to advance electrical energy storage.
FIRST, a collaboration with Argonne National Laboratory, Ames Laboratory and seven universities, is keeping Dai busy these days. The center recently won funding for another four years of work, and represents a true team effort, according to Dai. “We’re trying to push the envelope for energy storage, and achieve simultaneous high electrical power and energy delivery. The need for a deeper understanding of how ions transport in electrolytes and in the electrode is a bottleneck for energy storage devices, particularly for fast charging and discharging.”
Dai is involved in several other projects supported by DOE’s Office of Science (Basic Energy Sciences’ Separations program), largely centered on how to control molecular or ionic interactions to develop a host that can selectively recognize and separate certain substances, such as carbon dioxide. When those interactions can be controlled it can lead to higher selectively for targeted substances and enhanced transport properties of those species across a membrane or other media.
It is a fundamental strategy that can apply to separations in a number of different areas, including a high-profile project funded by DOE’s Office of Nuclear Energy that created an adsorbent for the separation of uranium from seawater. ORNL researchers in that multi-institutional project developed a polymeric adsorbent material to selectively bind uranium from the ocean’s immense chemical soup.
The results of the uranium/seawater project could be applied to the grand challenge of clean water—particularly desalination and the treatment of water after it is used in industrial processes such as hydraulic fracturing. “The sorbent material could be used to extract minerals or metal ions from wastewater streams,” Dai noted. While this solution tackles desalination through chemical binding, he was a key contributor to a project that tackled desalination with the help of electrochemistry. For this project, he developed mesoporous carbon for capacitive deionization electrodes—work that netted an R&D 100 Award in 2011.
That particular breakthrough in mesoporous carbon materials holds great promise for applications such as the separation of carbon dioxide or the storage of energy. The associated publication, “Mesoporous carbon materials: Synthesis and modification,” appearing in Angewandte Chemie in 2008, is one of his most highly cited, with 1,138 citations total.
“We often think that our inspirations start with basic science, and we then use what we learned as a cornerstone for applied technology,” Dai said. “But I think it works both ways: we can draw inspiration from applied science for basic research.”
Collaboration as a key to success
A hallmark of Dai’s work has been participation on large, collaborative teams, and it’s a practice he hopes will continue among young scientists at the lab.
“ORNL is the ideal place for me,” Dai said. “We have a tremendous amount of different disciplines here, even within chemistry and materials science. With our neutron and microscopy facilities—there’s nowhere else in the world where you’ll find all this under the same roof. I can collaborate with a physicist just across the way. I have a project with a scientist in another division where we’re exploring the use of ionic liquids for lubrication. I don’t think you would see this so easily done in another place.”
He urges early career scientists to ”set your goals higher, make your vision broader, and try to have the attitude that you are a team player, not an empire builder,” Dai said. “Very much like a tree, you need to have deep roots. Interact with others who are in different disciplines; good colleagues will always provide you with a reality check. It’s important for young staff to remain focused and not have too much ego. You can complain forever in any organization, but those who just do their work and treat colleagues well are the most successful. Here you can not only make a big impact and advance your own career, but you can encourage others in their careers too. You should have a goal to participate in a big collaborative project.”
Dai grew up in China, with a father who was a middle school principal and a mother who was a teacher. He earned his bachelor’s and master’s degrees in chemistry from Zhejiang University in Hangzhou, China, and a PhD in chemistry from the University of Tennessee. He joined ORNL in 1990 as a postdoctoral fellow, initially studying molten salts for nuclear energy applications—an area of innovation for ORNL that includes the 1960s Molten Salt Reactor Experiment, which continues to offer valuable insights.
“Never say never,” Dai laughs. “Now we’re back to molten salts—with a new flavor.”
The new work is related to the use of molten salt as a heat transfer medium and for thermal energy storage in concentrated solar power projects that operate at high temperatures. Given the history of molten salt research at ORNL, “we’re not reinventing the wheel. We will leverage our previous knowledge of molten salts, and once again we’ll be trailblazers,” Dai said.
Dai is also heavily involved in research around ionic liquids (salts that are liquid at room temperature) and a new class of porous materials that have the potential to open up vast opportunities in chemical separations, and in building new catalytic interfaces to create new, controlled reactions.
Meanwhile, the scientist has not forgotten his love of painting. He keeps a portrait he painted in the 1970s in his office, and tries to find time to sketch when he is traveling. “When I’m waiting in airports I’m more likely to be answering emails these days,” he said. “When I retire, I hope to get back to painting.”
ORNL is managed by UT-Battelle for the Department of Energy's Office of Science, the single largest supporter of basic research in the physical sciences in the United States. DOE’s Office of Science is working to address some of the most pressing challenges of our time. For more information, please visit https://science.energy.gov.