Toward CO2 Conversion to Renewable Fuel - Nelson Robinson Science & Tech. Award for Renewable Energy

Stafford Sheehan of Air Company discusses his work at Air Company, which has commercialized several luxury products (spirits, sanitizer, and fragrance) that use ethanol made by chemically reducing CO2 using H2O, and renewable electricity. Dr. Sheehan is the recipient of the 2021 MRS Nelson "Buck" Robinson Science and Technology Award for Renewable Energy.



2021 Kavli Early Career Lectureship in Materials Science

Cementing a Low-Carbon Future Infrastructure – 2021 Kavli Early Career Lectureship in Materials Science. The large amounts of cement and concrete needed to fulfil modern infrastructure needs make them contribute up to 10% of CO2 global emissions. Susan Bernal Lopez, University of Leeds, discusses her MRS Fall Meeting Kavli Early Career Lecture which provides an overview of recent advances in the materials science of novel low carbon cement, with a fraction of the CO2, highlighting the challenges and opportunities for their development and industrial widespread uptake.



David Turnbull Lectureship Presentation

Wednesday_Turnbull_800 WideNicholas A. Kotov, University of Michigan

Nanoscale Biomimetics: From Self-Assembled Nanocomposites to Chiral Nanostructures

Written by Prachi Patel

The Turnbull Lectureship recognizes someone who has contributed to the fundamental understanding of the science of materials. True to that spirit, Nicholas Kotov’s work has laid the foundation for a deeper understanding of the biomimetic self-assembly of nanoparticles. “It’s my job to tell you what biomimetic structures are, why they are important, and what difference in the world these structures make,” he said during his Turnbull award speech.

Nature is rife with complex nanostructures composed of nanoparticles that self-assemble due to varying anisotropies. Nacre and bone are prime examples, where layered organization of nanocomponents results in “wonderful mechanical, optical and transport properties,” he said. “The question of course is how do we replicate this?”

He and his colleagues have replicated the brick-and-mortar structure of nacre, for instance, by assembling various materials such as graphene and cellulose in a layer-by-layer manner. This has given materials with combinations of properties such as electrical and thermal conductivity that were previously unseen, and the technological applications for such materials.

Nacre, however, is a fairly simple structure. Kotov’s group is developing experimental, theoretical, and computational techniques to engineer more sophisticated hierarchical structures.

Two key things drive the assembly of complex structures, he said. One is dispersity, which is a measure of the diversity of particle sizes, and the other is competing chirality-dependent assembly restrictions.

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His group has shown that inorganic nanoparticles with polydispersity, (i.e., non-uniform size distributions,) self-assemble into uniformly sized super-particles via a process driven by the tension between electrostatic repulsion and van der Waals attraction.

Chirality plays a key role in interparticle interactions which lead to self-assembly. The researchers assembled anisotropic iron diselenide nanoplatelets into spiky spheres, which they call hedgehog particles. By changing the chiral fraction of cysteine, they controlled the assembly of gold–cysteine nanoplatelets into visually complex hedgehog particles with twisted spikes. Utilizing electrostatic restrictions lets them form a wide range of chiral particles such as bowties, star-shaped, or a super-particle of super-particles.

The complexity of complex nanoparticles is related to functionality, he said. For example, super-particles made from chiral zinc sulfide and gold nanoparticles have a Goldilocks complexity—not too high, not too low—that provides new functionality. These super-particles serve as efficient photocatalysts for oxidative coupling of phenols, which is notoriously difficult to do.

Kotov has used graph theory to measure the complexity of the self-assembled nanoparticles, and found that they are more complex than “biological materials forged in nature,” he said. “We started to replicate strength but then took it further.”

His group is now using graph theory methods to understand where complexity comes from, and use the complexity measure to design desired particles with the aid of machine learning techniques. “Complexity emerges from the competition of restrictions, mainly electrostatic and symmetry restrictions,” he said. “If they have to fight each other that makes the system choose complex pathways to satisfy all the restrictions.”


Nicholas Kotov of the University of Michigan received the 2021 David Turnbull Lectureship for "foundational discoveries in interface-based engineering of self-organizing materials."

The David Turnbull Lectureship recognizes the career contribution of a scientist to fundamental understanding of the science of materials through experimental and/or theoretical research. In the spirit of the life work of David Turnbull, writing and lecturing also can be factors in the selection process.

Von Hippel Award Presentation

Wednesday_Von Hippel_800 Wide_3Harry Atwater, California Institute of Technology

Trip the Light Fantastic

Written by Don Monroe

We are in the throes of a second optics revolution, Harry Atwater asserted, as we continue to learn about manipulating light with structures that are smaller than the wavelength—unlike the lenses and mirrors of the first revolution. His talk illustrated the breadth and imagination that earned him the Von Hippel Award, covering three very different “Grand Challenges” for exploiting the interactions of light with nanostructured materials.

The first challenge concerns delivering solar energy whenever it is needed. For photovoltaic cells, this means continuing to improve efficiencies to make up for inevitable storage losses. The fundamental limits to quantum efficiency are well established, and several materials systems have been approaching these limits. A less familiar limitation arises from poor radiative efficiency, which can be improved with better optical design. Atwater (with Eli Yablonovitch) founded Alta Devices to accomplish this using thin materials that can be lifted off a substrate to allow better back-reflectors, setting efficiency records.

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A more direct approach to “dispatchable” solar energy emulates photosynthesis by generating hydrogen and reducing carbon dioxide in a photoelectrochemical cell. Atwater noted that the rhodium catalyst can be made transparent when it takes the form of 10-nm-scale particles, and the resulting cell converted solar energy to hydrogen with more than 15% efficiency. “There’s still lots of work to do” in these cells, he acknowledged, to ensure stability and continued catalytic activity in the extreme chemical environment.

His team has also explored novel Schottky-barrier structures in which photogenerated hot carriers cause CO2 reduction.

Atwater’s second grand challenge involves steering of light. Over the last 20 years, his group and many others have used patterned metasurfaces to manipulate optical wavefronts, to create flat lenses and other devices: “We can rewrite Snell’s Law” of refraction by introducing phase gradients across a surface, he said.

Atwater highlighted the opportunities in marrying these techniques with active devices to create metasurfaces with electronic control. He showed a flat lens with a tunable focal length, as well as beam steering with megahertz speeds. Inverse design methods allowed his team to generated non-intuitive phase profiles that eliminate extraneous diffraction orders. Applications could include LiDAR, “LiFi,” and holographic displays, among others.

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The third grand challenge is to “ride light to the stars,” or at least send humanmade structures to an exoplanet within the lifetime of people alive today. There is a habitable-zone planet orbiting the Proxima Centauri, “only” four light-years away. Ordinary rockets are limited by the speed of their exhaust, about 20 km/s for chemical propulsion (making the trip last tens of thousands of years) or 300 km/s for plasmas, Atwater said. “We have to break the speed limit.”

The Breakthrough Starshot initiative aims use reflected light to achieve 20% of the speed of light and reach that planet within 20 years of launch. This “audacious” plan “requires nearly miraculous technologies,” Atwater admitted, including the most powerful laser ever made, at about 100 GW, shining on a light sail many meters in size with a mass of order one gram.

Atwater and his team have explored nanophotonic techniques for the sail design, to provide very high reflectance with minimal absorption and weight. They have also devised (and tested at laboratory scale) optical metastructures that overcome the natural instability of flat objects under radiative force. Their designs could keep the sail centered on the driving laser, similar in principle to optical tweezers.

Even the sky is not the limit, it would seem, in this new optical age.

The Von Hippel Award, the Materials Research Society's highest honor, recognizes those qualities most prized by materials scientists and engineers—brilliance and originality of intellect, combined with vision that transcends the boundaries of conventional scientific disciplines.

Harry Atwater received the award “For fundamental research in light-matter interactions—particularly nanophotonics, plasmonics, photonic metamaterials, and solar energy conversion—and numerous applications of photon control of materials illustrating the value of fundamental research to technologies that improve the quality of life.”


Plenary Session Featuring The Fred Kavli Distinguished Lectureship in Materials Science

Plenary_HeadshotSir J. Fraser Stoddart, Northwestern University

Artificial Molecular Machines Going from Solution to Surfaces

Written by Don Monroe

Fraser Stoddart has been a pioneer in molecular machines, as recognized by sharing the 2016 Nobel Prize for Chemistry. A useful feature for these structures is the “mechanical bond,” such as that which holds together interlocking molecules, such as a ring-shaped molecule surrounding a dumbbell-shaped one. Among chemistry advances, “a new chemical bond is extremely rare,” he noted.

In his Kavli lecture, Stoddart focused on artificial molecular pumps that exploit this feature and add extra elements to achieve unidirectional motion. But he stressed that these pumps “don’t operate like the mechanical ones” that humans have used for millennia. “It’s a world of difference.”

In the nanomolecular pumps, the free-energy terrain is changed, allowing the molecules to jump around between different accessible states. “It’s all about kinetics,” rather than thermodynamics, he said. The kinetics of association and dissociation can be modulated by changing the charge state of radicals, for example by changing oxidizing or reducing conditions chemically, or electrochemically with an applied voltage.

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Many of the structures Stoddart described use a “pumping cassette” that loads a charged ring-shaped radical onto a “collecting chain” where it is mechanically bound. This process can be repeated to load additional rings, with little increase in the free-energy cost. His research team has loaded as many as 80 rings onto a star polyethylene glycol, incorporating 344 positive charges.

Attaching pumping cassettes to both ends of a chain can double the loading. Stoddart noted that this technique can create a symmetrical loading of molecules, which could in principle be used to make palindromic polymers of the rotaxane ring molecules.

Moving away from solution chemistry, Stoddart illustrated the tethering of molecular pumps to a metalorganic-framework membrane. The result is what he termed “mechanisorption” to the membrane. Unlike the well-known physisorption and chemisorption, driven by van der Waals or chemical bonding, respectively, this process is intrinsically far from equilibrium, and is made possible by mechanical bonding.

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Stoddart also mentioned the potential for molecular nanotopology (formerly called chemical topology) to form various interlocking ring-like structures, including knots, belts, and Möbius strips. (The linear molecules employed for his molecular pumps do not satisfy this description.) “There are eight million knots, so we can keep chemists and materials scientists occupied for centuries,” he said, since only about a dozen have been made so far.

Although Stoddart admitted that he is “not an applications scientist,” he expressed the hope that the tools and techniques his group has developed could be helpful for battery technology and hydrogen storage as well as capture of CO2 and methane. He also expects that there will be huge opportunities in medical science, in view of the profound importance of biological molecular pumps.

The Kavli Foundation is dedicated to advancing science for the benefit of humanity, promoting public understanding of scientific research and supporting scientists and their work.

Best Oral Presentation Awards

Akriti Akriti, Purdue University
EN06.02.06—Late News: Quantized Halide Diffusion in 2D Perovskite Vertical Heterostructures

Virgil Andrei, University of Cambridge
EN02.06.03—Late News: Rational Design of Photoelectrochemical Perovskite-BiVO4 Tandem Devices for Selective Syngas Production

Jesus Canas, Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, Universidad de Cádiz
EL04.11.05—Normally-OFF Diamond Reserve Blocking MESFET

Wei Chen, Université Catholique de Louvain
EN07.12.09—Late News: Origin of Low Conversion Efficiency of Cu2ZnSnS4 Kesterite Solar Absorber—The Actual Role of Cation Disorder

Jacob Cordell, Colorado School of Mines, National Renewable Energy Laboratory
EL03.05.02—Configurational Order-Disorder Transitions in ZnGeN2

Phillip Dang, Cornell University
NM01.03.05—Late News: An Epitaxial GaN/NbN Heterostructure Exhibiting Concurrent Superconductivity and Quantum Hall Effect

Shuo Feng, Pacific Northwest National Laboratory, Washington State University
EN09.04.02—Rational Design of Sulfur Cathode for High-Energy Lithium-Sulfur Batteries

Marco Gigantino, ETH Zürich
EN05.02.06—Pure and Mixed Metal Oxides for High-Temperature Thermochemical Energy Storage via Reversible Redox Reactions

Hongchen Guo, National University of Singapore
SM06.05.04—Artificially Innervated Foams—Biomimetic Self-Healing Synthetic Piezo-Impedance Sensor Skills

Justin Hoffman, Northwestern University
EL02.03.04—Long Periodic Ripple in a 2D Hybrid Halide Perovskite Structure Using Branched Organic Spacers

Jesse A. Johnson, University of Florida
CT02.05.02—Time Resolved Reflectometry With Pulsed Laser Melting of Implant Amorphized Si1-xGex Thin Films

Vincent Kadiri, Max Planck Institute for Intelligent Systems, Universität Stuttgart
SM06.01.03—Materials for Magnetically Actuated Micro and Nanorobots

Jonas Kaufman, University of California, Santa Barbara
EN03.03.03—Hierarchical Intercalent Orderings in Layered Oxides for Na- and K-Ion Battery Electrodes

Fabian Landers, Swiss Federal Institute of Technology (ETH) Zurich
SM06.01.06—3D Metal-Organic Microrobots

Ciana Lopez, University of Washington, Seattle Children's Research Institute
SM04.09.04—Late News: A Platform for Macrophage—Mediated Delivery of Polymeric Prodrugs to Solid Tumors

Hanieh Moradian, Helmholtz-Zentrum Geesthacht, Berlin-Brandenburg Center for Regenerative Therapies (BCRT), University of Potsdam
SM04.06.03—Nucleic Acid Co-Delivery-How to Modulate Protein Co-Expression by Formulation of Payload

Hyunseok Oh, Massachusetts Institute of Technology
ST04.02.02—Short-Range Order Strengthening in 3D Transition Metal-Based Complex Concentrated Alloys

Mizuki Ohno, The University of Tokyo
NM03.09.06—Late News: Two-Dimensional Quantum Oscillations Observed in Magnetic Topological Semimetal EuSb2 Films

Carlos Portela, Massachusetts Institute of Technology
ST03.03.06—Late News: Nano-Architected Carbon for Supersonic Impact Mitigation

Ahmed Tiamiyu, Massachusetts Institute of Technology
ST01.12.06—Microparticle Impact at Very High Velocities Does Not Necessarily Improve Bonding

Jiayue Wang, Massachusetts Institute of Technology
EN10.03.04—Tuning Metal Nanoparticle Exsolution on Perovskite Surface with Strain-Modified Point Defect Formation

Max Wood, NASA Jet Propulsion Laboratory, Northwestern University
EL03.07.02—The Effect of Multi-Band Transport on Thermal Conductivity Seen in Yb14Mg1-xAIxSb11

Yadong Yin, University of California, Riverside
EL06.02.03—Late News: Plasmonic Nanostructures for Photothermal Conversion

Edoardo Zatterin, European Synchrotron Radiation Facility
CT03.03.05—Local Structure and Switching of Ferroelectric/Ferroelastic Superdomains Probed by Scanning X-Ray NanoDiffraction

Wenjie Zhou, Northwestern University, International Institute for Nanotechnology
NM05.07.02—Shape-Driven, DNA-Mediated Engineering of Colloidal Superlattices

Congratulations to the 2021 Virtual MRS Spring Meeting Science as Art Winners!

First Place