On the second floor of the Chemistry 1958 building, just above the general chemistry labs, the Mallouk research group is busy at work. Between long lines of lab benches, computer desks, and even a small glassblowing workshop, their work spans a wide range of applications, from motors smaller than the width of a human hair to biologically-inspired solar batteries.
Thomas Mallouk, who came to Penn’s Department of Chemistry in May, and his team work in the area of materials chemistry and have several ongoing projects on renewable energy and sustainability. Mallouk is also the Vagelos Professor in Energy Research at the Vagelos Institute for Energy Science and Technology (VIEST), where he will support ongoing and burgeoning collaborations between the School of Arts and Sciences and the School of Engineering and Applied Science.
Mallouk and the students in his lab bring a unique approach to fundamental chemistry research. “Our most effective work has been taking somebody else’s problem, often an engineering or physics problem, fields populated by very smart people who have one thing in common: They’re not going to synthesize something new,” explains Mallouk. “Then we try to apply what we know about chemistry to their problem.”
One problem that Mallouk is excited to pursue further is energy conversion and energy storage in solar cells. Because solar energy is costly to store, the energy has to be used or converted at the same time it’s collected. A viable long-term storage solution would allow solar energy to be used during seasons or days when there is less light available, and Mallouk’s group is focused on gaining fundamental insights using electrochemistry research to get there.
Several researchers in his group, including graduate student Zhifei Yan, use inspiration from biology to build dye-sensitized solar cells that convert solar energy into electricity, hydrogen, or other energy-rich fuels such as methanol. “It’s an inorganic mimic of a biological system, like a plant,” explains Yan. “The ‘leaf’ absorbs the energy, and then it oxidizes water into oxygen and reduces carbon dioxide into compounds that store energy in chemical bonds.”
The Mallouk lab also works on 2D materials, atomically-thin synthetic
materials that exhibit new properties due to their atoms being confined to two dimensions. Postdoc Luis de Jesús Baez is studying the different aspects of these unique materials, and how their properties can be tuned. “We can synthesize, stabilize, and make the materia] better. We can functionalize their structures and make them do specific work, like CO2 reduction or for energy storage in batteries and supercapacitors,” de Jesús Baez says.
But it’s not all about energy. The Mallouk lab has also been working with autonomously powered nanoscale and microscale swimmers, about the size of a bacterial cell, that are propelled by either electrochemical reactions or ultrasound. Graduate student Jeff McNeill is looking for ways to control their movements using magnetism and is also exploring ways to power the microrobots with different fuels, like urea or glucose, so they could be used inside of the human body.
And while these microscopic swimmers have a number of possible applications, from cleaning wastewater to delivering drugs, Mallouk says he enjoys working on this project in part for the fun of it. “The problem of anthropogenic climate change has become increasingly urgent, and this motivates our focus on energy-related projects. But we also want to explore pure science questions, and that is what our nanomotor project is about,” he says.
Whether the group is focused on sustainability, energy, or miniaturized motors, the approach is always the same: Focusing on problems and using their expertise in materials chemistry to find a solution. “We want to solve problems by understanding the fundamental processes that are happening and then solving it little by little,” says de Jesús Baez. “There is beauty in tackling problems by considering different perspectives.”
By actively collaborating with other groups, including several engineering labs, the members of Mallouk’s group are able to diversify their skillsets and focus on problems without limiting themselves to one method or area of study. “It’s easier to do interdisciplinary work,” says Yan about their group’s approach. “We borrow from other areas, so we won’t limit ourselves to just electrochemistry. We just solve the problem.”
But because of the broader nature of their work, de Jesús Baez says, collaborations are instrumental for delving deeply when a problem requires a closer look. “Sometimes you want to get into that specific detail that will really hit the nail on the head. If you look from too high you may forget to look at the small things, and collaborations help you maintain this view in focus,” he says.
Because of the importance of collaboration in his group’s progress, Mallouk says that coming to Penn at this stage of his 34-year career was the perfect move. “More and more, chemistry is becoming very interdisciplinary and integrated with other sciences, and that happens here at Penn a lot. There’s an opportunity for a tremendous number of new collaborations here,” he says.
Mallouk’s students and postdocs, all of whom were responsible for physically packing up the lab and shipping the numerous boxes of equipment and supplies to Philadelphia earlier this summer, are also looking forward to the new types of research that they can do here. “It will be really nice having the med school right there,” says McNeill. “I could envision myself sitting down with a physician and saying, ‘What can we do with these nanomotors and materials that would be beneficial to you?’”
Mallouk is also looking forward to working with VIEST, where he will serve on the executive committee and manage resource allocations for internal grant proposals. He also hopes to gain some externally-funded projects on energy in the future. VIEST “is a lively place that brings people together with all different kinds of expertise and gets us talking and thinking of energy-relevant ideas,” says Mallouk.
VIEST director Karen Goldberg says that bringing Mallouk to Penn is a huge win for the Institute. “We are looking forward to Mallouk playing a leading role in our solar energy conversion efforts. His expertise in electrochemistry and materials is unparalleled, and his team brings unique vision, tremendous knowledge, diverse instrumentation, and wonderful scientific curiosity and enthusiasm,” she says.
Mallouk will be teaching general chemistry in the fall and is looking forward to “assembling an army” of undergrads for his lab. They will join the 10 graduate students and two postdocs who moved with him from Pennsylvania State University, as well as two new Ph.D. students who have joined the group at Penn. But looking beyond his first year of teaching and getting his lab established, Mallouk says that he’s excited for what the future has in store for his research group.
“I want to continue to work on good fundamental science,” he says. “We often diffuse into areas just from a chance conversation, but we’ve had a very long focus on energy, an increasingly urgent problem, so I want to continue to work in that area.”