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 solar energy conversion devices. Dye-sensitized solar cells, developed over two decades ago by Michael Gratzel and coworkers, can use the solar spectrum more efficiently when they are coupled to nanostructures that trap visible light or selectively re-direct infrared light to a silicon solar cell. In a collaborative project with the Lakhtakia and Mayer groups, we are now exploring solar cell designs that combine plasmonic (metal) nanostructures and periodic dielectrics (photonic crystals) to control the flow of light. By incorporating nanoparticles that catalyze water oxidation into dye sensitized solar cells, it is 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 spectroscopic techniques to measure their kinetics. These studies have recently led to a better understanding of system-level problems in the photoelectrolysis of water, and to the design of more efficient electrolyzers for converting CO₂ to fuels and chemicals.

Template Synthesis of Nanowires and Metamaterials

Several projects in the group use porous membranes and colloidal crystals as templates for making nanomaterials. Multi-segment nanowires have interesting electronic properties, such as transistor and diode behavior and in some cases unusual low temperature transport properties. In collaboration with the Sen, Velegol, Cremer, and Crespi groups, we are studying the movement of multi-segment nanorods powered by spontaneous catalytic reactions. These nanorods were the first examples, outside of biological systems, of autonomously powered nano- and micromotors. In many ways, they resemble living microbial motors 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 Mauricio Hoyos and Angelica Castro at ESPCI in Paris, we have recently discovered that micron-size metal "rockets" undergo a range of autonomous and cooperative motion when propelled by acoustic waves. These new motors are biocompatible and exhibit fast directional motion at ultrasonic power densities that are typically used in medical imaging. In collaboration with the Badding group in the Penn State MRSEC, we are using colloidal crystal templates to synthesize and study metalattices of semiconductors, ferromagnets, and other materials.

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. Layer perovskites, 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. In collaboration with the Crespi and Terrones groups, 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 catalyst supports, as electrode materials for batteries, and as ionic conductors.

Selected Publications

L. Ren, D. Zhou, Z. Mao, P. Xu, T. J. Huang, and T. E. Mallouk, "Rheotaxis of bimetallic micromotors driven by chemical-acoustic hybrid power," ACS Nano, 11, 10591-10598 (2017).

Y. Gao, Y. Zhao, Y. C. Li, Q. Huang, T. E. Mallouk, and D. Wang, "Interfacial chemistry regulation via a skin-grafting strategy enables high-performance lithium-metal batteries," J. Am. Chem. Soc., 139, 15288-15291 (2017).

Y. C. Li, D. Zhou, Z. Yan, R. H. Goncalves, D. A. Salvatore, C. P. Berlinguette, and T. E. Mallouk, "Electrolysis of CO₂ to syngas in bipolar membrane-based electrochemical cells," ACS Energy Lett. 1, 1149-1153 (2016).

X. Fan, P. Xu, Y. C. Li, D. Zhou, Y. Sun, M. A. T. Nguyen, M. Terrones, and T. E. Mallouk, "Controlled exfoliation of MoS₂crystals into trilayer nanosheets," J. Am. Chem. Soc., 138, 5143-5149 (2016).

M. E. Strayer, T. P. Senftle, J. P. Winterstein, N. M. Vargas-Barbosa, R. Sharma, R. M. Rioux, M. J. Janik, and T. E. Mallouk, "Charge transfer stabilization of late transition metal oxide nanoparticles on a layered niobate support," J. Am. Chem. Soc. 137, 16216-16224 (2015).

Y. Zhao, N. Vargas-Barbosa, M. E. Strayer, N. S. McCool, M.-E. Pandelia, T. R. Saunders, J. R. Swierk, J. Callejas, L. Jensen, and T. E. Mallouk, "Understanding the effect of monomeric iridium(III/IV) aquo complexes on the photoelectrochemistry of IrO_x.nH₂O-catalyzed water-splitting systems," J. Am. Chem. Soc., 137, 8749-8757 (2015).

W. Wang, W. Duan, S. Ahmed, A. Sen, and T. E. Mallouk, "From one to many: dynamic assembly and collective behavior of self-propelled colloidal motors," Acc. Chem. Res., 48, 1938-1946 (2015).

J. R. Swierk, D. D. Mendez-Hernandez, N. S. McCool, P. Liddell, Y. Terazono, I. Pahk, J. J. Tomlin, N. V. Oster, T. A. Moore, A. L. Moore, D. Gust, T. E. Mallouk, "Metal-free organic sensitizers for use in water-splitting dye-sensitized photoelectrochemical cells," PNAS, 112, 1681-1686 (2015).