Functional Hybrid Biotic/Abiotic Materials

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Non-Technical: This award by the Biomaterials Program in the Division of Materials Research to Emory University is to develop hybrid biotic/abiotic functional materials that will achieve light driven, multi-electron chemistry. Two essential features of living systems are self organization of complex structures and the associated compartmentalization of function, enabling them to extract energy from the environment and store it as fuel used to power all life processes. This proposal seeks to mimic these essential characteristics of living systems by developing artificial materials that use biotic/abiotic interfaces to enable efficient harvesting of light energy and its storage as fuel in high energy density chemical bonds. The proposed work will develop a new class of biotic/abiotic materials based on the integration of nano-structured semiconductor materials, so-called quantum dots, with enzyme biocatalysts. The quantum dots are designed to efficiently collect light and in the process generate electrons that can be used for doing chemistry. The biocatalyst efficiently generates the fuel hydrogen from water when given a ready supply of electrons. The unique properties of the biological catalyst (self assembly and the ability to tailor the interface by structural evolution) will be used to properly wire the two components together into a hybrid material that is stable, robust and efficient at converting light into hydrogen fuel. This project also provides a unique training opportunity for high school and undergraduate students because it integrates multiple disciplines, including molecular biophysics, spectroscopy and materials science, to solve a problem of direct practical relevance.Technical: Storing light energy in high energy density chemical bonds requires new functional materials to achieve: 1) efficient light harvesting; 2) long-lived charge separation; 3) interfacial charge transfer to a catalyst; and 4) robust catalysts for multi-electron chemistry. The proposal is to develop hybrid materials that integrate a light harvesting and charge separation component with a highly efficient biocatalyst. The specific objectives are: 1) to design, synthesize and characterize hybrid hydrogenase:quantum dot functional materials; 2) to determine the interfacial structures and dynamics that affect function; and 3) to develop photo-electrodes based on the hybrid materials that are capable of light driven hydrogen production. A major challenge is the inherent single electron nature of photosensitizers, which has been the primary limitation of their efficient application to light driven redox chemistry. The proposed work will test whether quantum confined semiconductor materials are capable of acting as multi-electron photosensitizers, by generating and harvesting multiple excitons to drive catalytic chemistry. The proposed work will serve as a foundation for teaching and training students highly interdisciplinary skills in molecular biophysics, spectroscopy and materials science, through the Emory Chemistry Intern Program for high school students, and the Emory Summer Undergraduate Research Experience.