HUMAN BEINGS HAVE BEEN CONSUMING ENERGY on a large scale for only a few centuries, but nature has been perfecting her techniques for billions of years. Whether it is transforming sunlight into fuel or producing chemicals without unwanted byproducts, nature has a lot to teach us. The new Kavli Energy NanoSciences Institute (Kavli ENSI) at the University of California, Berkeley, and the Lawrence Berkeley National Laboratory was founded to learn those lessons. Its goals are to study how nature manages energy at the nanoscale – sustainably and often with exceptionally high efficiencies – and to develop entirely new ways to capture, store, and harness energy for the world’s growing population. Strongly cross-disciplinary, its 17 members – many of them influential leaders in nanosciences –bring perspectives that span the fields of physics, biology, chemistry, and engineering to their institute collaborations.
The Kavli Foundation brought together the institute’s director, Paul Alivisatos, and its two co-directors, Omar Yaghi and Peidong Yang, to discuss the Kavli ENSI's goals and the emerging science of energy conversion at the nanoscale.
- Paul Alivisatos is the director of the new Kavli Energy NanoSciences Institute and former director of the Lawrence Berkeley National Laboratory. He is currently Vice Chancellor, Provost, and holder of the Samsung Distinguished Chair in Nanoscience and Nanotechnology at the University of California, Berkeley.
- Omar Yaghi, Kavli ENSI co-director, is the James and Neeltje Tretter Chair Professor of Chemistry at University of California, Berkeley.
- Peidong Yang, Kavli ENSI co-director is the S.K. and Angela Chan Distinguished Professor of Energy and Professor of Chemistry at University of California, Berkeley.
The following is an edited transcript of the discussion.
PAUL ALIVISATOS: We created the Kavli Energy NanoSciences Institute to do two things: to study how nature manages energy at the nanoscale, and to create synthetic systems that use these principles.
Nature is an incredibly clean and efficient producer of energy, yet the principles and concepts at work at the nanoscale are new to us. Our goal is to try to understand the basic science of these processes.
OMAR YAGHI: I think about energy nanoscience in terms of chemical structure, so I'll answer that question from that perspective. We want to learn from nature to build unusual chemical structures, then use what we learn to create synthetic materials. For example, one concept we are just beginning to understand is the beautiful balance in nature between diversity and order.
What do I mean by that? Well, think of plastics. Their molecules consist of a single unit repeated over and over again. They are very regular and not at all diverse. But nature combines regular order with diversity, such as with DNA, which has a familiar backbone with a variety of chemicals hanging off it. This combination of order and diversity makes life possible. We see it everywhere, in teeth, bone, and blood vessels. We want to better understand this concept to make new materials so we can study how light and electrons propagate through their energy landscapes.
PEIDONG YANG: As Omar points out, nature provides many examples of nanoscopic components pieced together in molecules to achieve a certain function. Another example involves energy conversion in a leaf. All sorts of nanoscopic components must interface with one another in order to do photosynthesis effectively. We would like to put together synthetic nanoscopic components that mimic nature to convert sunlight into fuel. My goal is to work with other collaborators at the institute to take different nanoscopic components, each of which does something different, and program them to assemble into more complex systems. Then we can try to channel energy to the right place at the right time and introduce the right chemistry to convert and store solar energy like a leaf.
TKF: So the goal is to learn at the nanoscale how nature creates clean, efficient energy, then use what we learn to create technologies that help meet energy needs at the large scale, or in areas where other clean and renewable energy sources are not easily available, correct?
ALIVISATOS: Yes. There is no question that meeting the growing demands for energy reasonably is one of the world’s most important challenges in this coming decade. It relates to such issues as sustainability, and whether people in the developing world will have the energy to enjoy a modern lifestyle. Yet most energy research efforts today are based technologies that have been around for decades and even centuries.
Nature may hold the key here. Again, nature is producing energy renewably and very efficiently, using principles we are only beginning to understand. Peidong, for example, mentioned the leaf. The leaf directs and channels light and energy in ways that are very, very different from what we do today. Omar and Peidong are leaders in mimicking what goes on in biological systems. Right now, it's important scientifically to understand those processes. And one day we may be able to apply those processes to energy systems that are used every day. We plan to start with the science and hopefully one day end up with the technology for commercial products that can make this happen.
YANG: Agreed. We want to learn how nature moves electrons, ions, photons, and molecules in very specific directions and then mimic these processes. Once we learn these tricks, we can turn this science into larger scale technology.
YAGHI: We have so much to learn. Take even the simplest transformation at the molecular level, how plants turn carbon dioxide into sugar or fuel. We have no deep knowledge of how that transformation actually takes place, much less how to design synthetic materials that can do this efficiently. But if we can do what Peidong suggests, and truly understand energy transformation at a deep level, we might be able to design materials that make exactly what we want – fuels and chemicals – and fewer unwanted by-products.
TKF: Why is this the right time to launch the Kavli ENSI?
YAGHI: We face great problems in the energy sector, such as the impact of carbon emissions on the environment. Before we can create new technologies to address these problems, we first need to do the basic research. To have an institute like this – an institute focused on the fundamental questions about nanoscale energy science – is something completely new and will be an important catalyst for one day developing these technologies.
YANG: I agree, and see two other reasons as well. The first is that we are really beginning to understand how nature links together nanoscopic components to form molecules and larger structures. It is an exciting time for studying nature. Second, nanoscience has come a long way. Today, we can design nanocrystals and nanostructures with specific properties. Now is a good time to think about how to assemble nanoscopic components and program their functionality to channel energy so all the synthetic units can work together cooperatively to accomplish something, like making fuel.
ALIVISATOS: Yes, we want to understand how nature operates on a very fundamental level. Nature has very tight control over its molecules. DNA, for example, stores, accesses, and process information in a very small scales. We've understood that for a long time.
What we're just beginning to understand now is that nature also employs tricks, some of them just as sophisticated or even more so, in energy conversion. Now is the time to investigate that.
YAGHI: Right. We are not only learning how to create complex objects, but also how to arrange them in a particular sequence to achieve a very specific property related to energy.
TKF: The Kavli ENSI brings together a number of top researchers from many different fields. What do they have in common?
YAGHI: Most of us are explorers. We want to go into some unusual areas. We're interested in how energy is used and manipulated at the nanoscale. By bringing together scientists and engineers from different backgrounds, we're creating a fertile ground for uncovering new concepts.
ALIVISATOS: The institute covers the range of disciplines - physics, chemistry, biology, engineering, mathematics – needed to make progress in energy nanoscience. What interested me was what happened when we began to discuss the institute. Everyone was working on similar problems involving nature's control of energy, but from very different perspectives.
For example, [Professor of Chemistry and Chemical Biodynamics] Graham Fleming was trying to measure what happens in photosynthetic systems, while Peidong was creating a synthetic photosynthesis system. [Professor of Condensed Matter Physics and Materials Science] Alex Zettl was trying to get nanostructures to move heat in one direction, while [Professor of Mechanical Engineering] Xiang Zhang was trying to do the same thing with photons. It made us feel that something united us. Yet our differences are important too. We all work in highly specialized fields, but it is communications between these narrow fields that leads to new ideas. I'm optimistic that will happen here.
TKF: This is a very diverse group. Do you have anything in common in terms of how you conduct your research?
ALIVISATOS: We've tried to bring together people who have really different approaches so we can look at problems from many different perspectives. These are approaches we each have taken a lot of thought and time to master in order to produce interesting results. For example, Omar, Peidong, and I all synthesize new materials, but we do this in very different ways. For instance, I work on controlling the shapes and connectivity of nanocrystals made in liquid solution while Omar does the exact inverse. He makes materials that have holes with intricate connections and shapes inside them. Peidong does many different things, but he tends to make objects that are more directional.
YANG: That is why our collective focus on fundamental discovery is so important. When we talk about energy conversion at the nanoscale, we're really talking about how we move heat, photons, ions, and molecules. There is a different set of scientific principles and mechanisms involved in moving each one of them. To build synthetic systems, we need to understand those principles but that is not enough. Our investigators need to interact so that we are not just focusing on transporting individual elements, but instead programming nanostructures to transport all these things cooperatively to do useful work.
ALIVISATOS: I'm looking forward to working with [Assistant Professor of Chemistry] Naomi Ginsberg and Graham Fleming, who have looked very deeply at the membranes of photosynthetic cells. These membranes contain intricately arranged patterns of light-absorbing molecules. People have always wondered why they needed to be so intricate. Naomi and Graham have shown that these arrangements reduce some interference effects as excited electrons move through the system, so plants can channel the electrons where they want them to go. That's pretty nifty. We'd like to try to make nanostructures, perhaps an arrangement of nanocrystals, which mimic that effect.
YAGHI: I see similar potential, but from a different perspective. The mystery we want to understand is how nature arranges its molecules to determine how they interact with molecules that pass through their space.
We can now place molecules where we want them. But can we arrange them so they channel molecules in a single direction along a prescribed path? We can think of it like an assembly line, but most assembly lines make just one thing. We want to program this assembly line to do things that are much more sophisticated than that. This is a new way of thinking about synthesizing synthetic molecules. It might enable us to make materials that can sort, count, or code molecules for particular transformations. We want to create synthetic enzymes, highly repeatable structures with irregularly shaped pockets that can synthesize chemicals. We want to understand what happens when we apply pressure or stretch them. As we design and test these structures, we will develop fundamental insights into nanoscale energy flow and transformation.
I'm looking forward to collaborating with Paul and Peidong to see what concepts are transferable. The center also brings together people who understand electron and photon flow, such as Alex Zettl, [Professor of Condensed Matter Physics and Material Science] Michael Crommie, and Xiang Zhang. So there are many researchers and colleagues who address these issues from different perspectives and who are potential collaborators.
YANG: I'm interested in working with many of the same people Omar mentioned, as well as [Professor of Chemistry] Gabor Somorjai. We are all interested in placing molecules in very specific sequences. Omar talked about multiple-step chemical transformations, and that is one potential project we could work on. By programming the assembly of a nanostructure with multiple interfaces, we could start with one reaction and then do sequential reactions on the same molecule and control the transport of energy through the system.
TKF: What are some technologies that make this research possible that weren’t available 10 or 20 years ago?
YAGHI: In the world I’m familiar with, new technologies for making better measurements have made a real difference. We have sophisticated x-ray diffraction and electron imaging techniques that let us acquire and analyze data rapidly. With electron microscopy, we can observe single molecules on a surface and even study their dynamics. In spectroscopy, solid state two-dimensional nuclear magnetic resonance technologies can measure the distance between molecules in very complex environments, so for the first time, we can map their exact arrangements.
ALIVISATOS: I think we're all seeing the same things: better instruments to observe nature, new capabilities to pattern and control matter, greater understanding of how nature manages energy at the nanoscale.
ALIVISATOS: As we learn from nature and then use what we learn to build new types of systems, I think we are going to see energy nanoscience advance along a very broad front.
YAGHI: I agree. Through collaborations we are already learning how to control the rate and directionality of the energy flow, and to do many things we only dreamt of a few years ago. Let me give an example based on my own research. As Paul noted, I make hollow materials with irregularly shaped pockets that connect to one another. This is the same type of structure some enzymes use to convert methane, the main component of natural gas, into methanol, which we could use as a liquid fuel or chemical feedstock. This is done by a complex enzyme, methane monooxygenase, which has two linked compartments. One is hydrophobic and attracts methane molecules, while the other is hydrophilic and attracts water. An iron-based catalyst sitting between them combines the two to form methanol. This exquisite arrangement of channels and catalysts is going to be a reality in synthetic materials. And as we build these structures, they will help us really understand the underlying energy transformations at the nanoscale.
YANG: Some part of my past research focused on controlling the heat and ion flow within individual nanostructures. I'm excited about exploring ways to combine these structures with the molecular components developed by other institute research groups. We want to do this in ways that synchronize the flow of energy and particles, so that these molecules work cooperatively to perform a desired function, like producing fuel.
TKF: Now looking ahead 20 years, what do you see as the impact of this research?
YANG: This institute's emphasis on cross-disciplinary research is likely to produce many fundamental discoveries over the next 10 or 20 years. I think we are going to learn how to synthesize nanostructures and systems that convert energy and produce fuel. These findings will form the basis of commercial technologies that will ultimately enable us to generate gigawatts of power.
ALIVISATOS: Peidong is exactly right. The things we're talking about could have real, practical impacts one day. By opening new fields of discovery, we will be stimulating new technologies.
— Summer 2013
"Nature is producing energy renewably and very efficiently, using principles we are only beginning to understand."
"Most of us are explorers. We want to go into some unusual areas. We're interested in how energy is used and manipulated at the nanoscale."
"This institute's emphasis on cross-disciplinary research is likely to produce many fundamental discoveries over the next 10 or 20 years."