MIT graduate students Kelsey Stoerzinger, Scott Grindy, and Ritchie Chen won Silver Awards at the Materials Research Society (MRS) 2015 Fall Meeting in Boston. They were among 29 Gold or Silver Award winners who were recognized for exceptional ability and a promising future in materials research based on oral presentations given on Dec. 1, 2015.
Stoerzinger, who is part of MIT Professor Yang Shao-Horn's Electrochemical Energy Lab, was honored for her work on "New Insights in Oxygen Electrocatalysis from Epitaxial Oxide Surfaces." She works on oxygen reduction catalysts for fuel cell applications.
"We know that oxygen reduction is the efficiency-limiting process for fuel cells, so it's the dominant source of (energy) loss," Stoerzinger, 27, explains. "We're interested in using oxide materials as Earth-abundant alternatives to platinum, which is the most active material for this reaction," she says.
Stoerzinger conducts research on oxide surfaces using ambient pressure X-ray photoelectron spectroscopy instruments at the Lawrence Berkeley National Lab in Berkeley, California. Her work on wetting and catalysis shows materials that interact weakly with water are better able to serve as catalysts, she says. She was lead co-author of a recent review paper on the technique entitled, "Insights into Electrochemical Reactions from Ambient Pressure Photoelectron Spectroscopy."
"We're looking at connecting the electronic structure of catalysts to how they react with water and then what that means in terms of their reactivity for oxygen reduction," she explains. She finds that materials that don't react, or react weakly, with water that is present in an electrolyte are more active for oxygen reduction. She expects to finish her PhD in spring 2016.
Scott Grindy, who is part of assistant professor of materials science and engineering Niels Holten-Andersen's Laboratory for Bio-Inspired Interfaces, was honored for his work on "Exploring Elasticity and Energy Dissipation in Mussel-Inspired Hydrogel Transient Networks." He works on high-strength hydrogels and recently published a paper, "Control of hierarchical polymer mechanics with bioinspired metal-coordination dynamics," in Nature Materials.
Reversible histidine-metal ion interactions are known to contribute to mechanical strength and self-healing properties of mussel byssal threads. These histidine-metal ion interactions also can be used to control mechanical properties of polyethylene glycol hydrogels. Grindy's work shows that elasticity is dominated by long-range entanglements, while the dissipation is controlled by the exchange kinetics of transient crosslinks. This understanding can yield high-strength hydrogel designs for specific loads.
Ritchie Chen, who works in Assistant Professor Polina Anikeeva's Bioelectronics Group, was honored for his work on magnetic nanoparticles for biomedical applications. His MRS presentation was titled, "Solvent-Optimized Redox Enables Synthesis of Nearly Defect-Free Ferrite Nanoparticles with Enhanced Hyperthermic Performance." Chen and colleagues published a paper, "Wireless magnetothermal deep brain stimulation," in Science.
These magnetic particles heat up in an alternating magnetic field and can be used for a variety of biomedical applications, including cancer treatment and deep brain stimulation. Chen finds that redox-active solvents enable synthesis of nearly defect-free iron-based nanoparticles with some of the highest heating efficiencies, or specific loss powers, reported. They also display low magnetic field frequency and amplitude relevant for clinical applications. These nanoparticles may be used as contrast agents for magnetic resonance imaging.
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R. Chen et al. Wireless magnetothermal deep brain stimulation, Science (2015). DOI: 10.1126/science.1261821