428604 Understanding Solar-Fuel Systems from the Nanoscale to the Device Level

Sunday, November 8, 2015
Exhibit Hall 1 (Salt Palace Convention Center)
Miguel Modestino, School of Engineering, École polytechnique fédérale de Lausanne, Lausanne, Switzerland

The world’s development and the implementation of a sustainable lifestyle depend on significant advances in the alternative energy sector. These advances will require basic scientific developments in energy generation, capture and storage as well as large scale economic policy drivers to motivate the necessary changes in our current energy infrastructure. Developing viable energy conversion technologies can significantly help trigger these changes. I have actively participated in the search for solutions to energy challenges with deep fundamental and technological implications in the field of artificial photosynthesis. Artificial photosynthesis devices are complex energy conversion systems that need to absorb sunlight, create and transport charges, and electrochemically generate energy rich molecules such as hydrogen that can be used as a fuel. Given the complexity of the process, integrated systems need to be designed to efficiently carry-out all of these processes in parallel. My research has tackled aspects ranging from the materials nanostructure level to the overall device design structure, with particular emphasis on the role of hybrid polymeric materials for solar-fuel generation. Here I will highlight research insights from the basic understanding of functional nanoparticle self-assembly in polymer membranes, to the structural and transport characteristics of ion-conducting polymers at inorganic interphases for electrochemical water splitting. Also, broader aspects on the implementation and device design of cost-effective solar-fuels technologies will be discussed.

Electrochemical energy conversion devices, such as the solar-fuel generators described above, rely strongly on active multifunctional materials in order to perform various electrochemical processes involved in their operation. Polymer composites can play a key role in the functioning of energy conversion devices, as they act as a versatile platform for the achievement of properties unattainable by single component material systems. Additionally, combining the properties of polymeric and inorganic materials, multifunctionality can be achieved with the potential to impact a wide range of energy applications. My proposed group’s research will focus in underpinning structure-property relationships of polymer composites in order to enable deployable energy conversion devices. We will depart from classical research schemes, and we will not only focus on fundamental aspects of particular material systems, but we will close the loop and design active materials envisioned to enable a particular technology or application. This would allow us to not limit ourselves to existing material problems of current devices, but to create disruptive technologies where the materials and device design go hand-in-hand and achieve unconventional functionalities. Within my scientific program, I will implement a research model that will iteratively circle around 3 pillars: (a) development of energy conversion devices and processes based on material properties, (b) development of multifunctional polymer composite materials to enable device functionality and (c) strong structural and physicochemical characterization of materials and devices.

Specifically, we will first design materials using basic physical models to understand the drivers for performance and potential for a particular application, as well as devise the required morphologies to achieve the desired functionality. Basic continuum models to describe transport properties (i.e. mass, heat and electrical), chemical processes, and the mechanical behavior of materials will inform my group about particular materials morphologies or device designs that satisfy the desired requirements for a given application. Then, we will devote the bulk of our research efforts to understand the self-assembly aspects of composites that lead to the required morphologies and functionalities. To achieve this goal, a wide range of polymer processing techniques and structural characterization tools will be used to obtain and assess composites’ internal structure. Methodologies to obtain materials that self-assemble into the desired morphology will be employed, as well as processing steps to kinetically trap morphologies that are not thermodynamically equilibrated. Characterization tools that will be instrumental into assessing the internal microstructure of materials include basic electron microscopy techniques such as scanning or transmission electron microscopy, as well as X-ray diffraction or scattering tools that can probe large volumes of materials. Specifically, my group will leverage my expertise in synchrotron materials characterization techniques such as small- and wide-angle X-ray scattering, SAXS and WAXS respectively, together with scattering modeling tools to elucidate the internal structure of active materials as they change during operation.  Lastly, understanding the effects of composites’ nanostructures on their properties (e.g. electrical, chemical and physical) will allow us to achieve optimized hybrid materials that can be implemented into devices and will also point out directions for improvements in their design.

Initially, this research model going from materials design to device implementation will be employed (i) to reinvent hybrid membrane-electrode assemblies used in water–splitting devices and (ii) to develop solid-state photocatalytic hybrid materials. In the future, and as my research program grows, I will leverage the knowledge, protocols and the infrastructure created in the initial projects to divert and expand my research program to other energy conversion systems. I anticipate that the initial proposed projects will provide the basic foundations and understanding of new hybrid materials that will enable a wide range of applications. Energy applications that the family of hybrid materials described above can tackle involve:  chemically resistant transparent conductors for solar-fuel applications, supercapacitor electrodes, and materials used in flow batteries.

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