Thomas Mallouk
Professional Appointments and Affiliations
Professor Emeritus
Evan Pugh University Professor of Chemistry, Biochemistry and Molecular Biology, Physics, and Engineering Science and Mechanics
Education
Sc. B., Brown University, 1977
Ph.D., University of California, Berkeley, 1983
Honors and Awards
AAAS Fellow, 2006
Priestley Undergraduate Teaching Award, 2006
Schreyer Honors College Teaching Award, 2007
ACS Award in the Chemistry of Materials, 2008
Member, American Academy of Arts and Sciences, 2009
ACS Fellow, 2013
Member, National Academy of Sciences, 2015
Research
Inorganic and analytical chemistry; synthesis of new materials; chemical applications of solid state materials: surface chemistry, layered and porous materials, self-assembly, artificial photosynthesis, catalysis and electrocatalysis.
Chemistry of Nanoscale Inorganic Materials
The Mallouk group is interested in several problems in materials chemistry, including photoelectrochemistry, electrochemical energy conversion, low-dimensional physical phenomena, and motion on the nanoscale. Our approach involves the synthesis of materials that contain molecular and/or solid state components, and the study of their structure, assembly, and properties by a variety of physical techniques.
Solar Photochemistry and Photoelectrochemistry
An important goal of this aspect of our research is to develop new kinds of nanomaterials that will lead to more efficient and less expensive energy conversion devices. Dye-sensitized solar cells, developed in the 1990’s by Michael Gratzel and coworkers, generate electricity from sunlight through light absorption by molecular dyes. By incorporating catalysts that enable water oxidation into dye sensitized solar cells, it is now possible to split water to hydrogen and oxygen using visible light. We use biomimetic principles to control electron and proton transfer reactions in these cells and transient electrochemical and spectroscopic techniques to measure their kinetics. These studies have led to a better understanding of system-level problems in the photoelectrolysis of water, to more efficient solar water splitting in biomimetic Z-schemes, to the design of electrolyzers for converting CO2 to fuels and chemicals, and to novel membrane concepts for alkaline fuel cells and redox flow batteries. Exploratory synthesis and high throughput screening enable us to discover better electrocatalysts and new inorganic ion conductors for these applications. The Mallouk group is part of the CHASE solar fuels hub project, the CABES energy frontier research center on alkaline electrochemistry, and CIMES, the Center for Ion Management in Electrochemical Systems.
Template Synthesis of Nanowires and Metamaterials
Several projects in the group use porous membranes and colloidal crystals as templates for making nanomaterials. In collaboration with other research groups at Penn and Penn State, we are studying the movement of asymmetric metallic and semiconducting nanoparticles that are powered by spontaneous catalytic reactions. These catalytic swimmers, created in collaboration with Ayusman Sen at Penn State, were the first non-biological examples of autonomously powered nano- and microswimmers. In many ways, they resemble living microbial swimmers and exhibit similar kinds of collective behavior. The principles of catalytically driven movement have now been used to design microscale pumps and rotors, and to study the powered motion of individual enzyme molecules. In collaboration with colleagues at ESPCI in Paris, we discovered that micron-size metal “rockets” undergo a range of autonomous and cooperative motion when propelled by acoustic waves. Microswimmers that contain on-board acoustic resonators can be propelled at remarkable speeds and with directional control in three dimensions. These new swimmers are biocompatible and function at ultrasonic power densities that are typically used in medical imaging.
Functional Inorganic Layered Materials
We are developing a set of soft chemical reactions that topochemically interconvert different structural families of layered and three-dimensionally bonded oxides. Layered metal oxides, metal phosphates, clays, and other lamellar solids can be grown layer-by-layer and converted to other interesting nanoscale morphologies (such as nano-scrolls and tubes) by means of intercalation, exfoliation, and restacking reactions. We are devising new ways to intercalate and exfoliate metal dichalcogenides, boron nitride, and graphite, without using redox cycles that damage the sheets. These unilamellar compounds are of particular interest as novel low-dimensional electronic conductors, as bipolar membrane catalysts, as electrode materials for batteries, and as hydroxide ion conductors. In collaboration with research groups at Penn, Penn State, and other institutions, we are also synthesizing and studying the emergent properties of materials that are porous on different length scales. We use porous colloidal crystals as templates to synthesize and study metalattices of semiconductors, ferromagnets, and other materials.
Selected Publications
E. Yamamoto, T. Gao, L. Xiao, K. Kopera, S. Marth, H. Park, C. Bae, M. Osada, and T. E. Mallouk, “Molecularly thin nanosheet films as water dissociation reaction catalysts enhanced by strong electric fields in bipolar membranes,” J. Am. Chem. Soc., 147, 14270–14279 (2025).
C. J. Sheehan, S. Suo, S. Jeon, Y. Zheng, J. Meng, F. Zhao, Z. Yang, L. Xiao, S. Venkatesan, A. S. Metlay, C. Donley, E. A. Stach, T. Lian, and T. E. Mallouk, “Electron transfer energetics in photoelectrochemical CO2 reduction at viologen redox polymer-modified p-Si electrodes,” J. Am. Chem. Soc., 147, 9629–9639 (2025)
C. Liu, T. Gao, L. Schulte, S. Marth, H. Park, C. Bae, and T. E. Mallouk, “Enhancing water management with three-dimensionally micro-patterned anion exchange membranes for alkaline fuel cells,” ACS Energy Lett., 10, 420–426 (2025).
T. Gao, L. Schulte, L. Xiao, A. S. Metlay, C. J. Sheehan, S. Marth, S. Sasmal, F. J. Galang, C. Bae, A. Z. Weber, S. W. Boettcher, and T. E. Mallouk, “Bipolar membranes with controlled, microscale three-dimensional junctions enhance the rates of water dissociation and formation,” Adv. Energy Mater., 2404285 (2024).
M. C. Özkan, J. M. McNeill, and T. E. Mallouk, “Zombie diatoms: acoustically powered diatom frustule biotemplated microswimmers,” Soft Matter, 20, 8012 – 8016 (2024).
L. Schulte, S. Qin, W. Jung, C. George, J. D. Dillenburger, A. Venkatesh, M. K. Ishak, N. M. Wonderling, S. Marth, H. Park, C. Bae, A. M. Rappe, and T. E. Mallouk, “Solid-State Hydroxide Ion Conductivity in Silver(I) Oxide, Ag2O,” Chem. Mater., 36, 11440–11448 (2024).
A. S. Metlay, Y. Yoon, L. Schulte, T. Gao, and T. E. Mallouk, “Langmuir-Blodgett deposition of graphite oxide nanosheets as catalysts for bipolar membrane electrochemistry,” ACS-AEM, 7, 7125–7130 (2024).
L. Xiao, J. A. Spies, C. J. Sheehan, Z. Zeng, Y. Gao, T. Gao, A. Ehrlacher, M. W. Zuerch, G. W. Brudvig, and T. E. Mallouk, “Electron transfer dynamics at dye-sensitized SnO2/TiO2 core-shell electrodes in aqueous/nonaqueous electrolyte mixtures,” J. Am. Chem. Soc., 146, 18117–18127 (2024).