Biomaterials Interfaces for Photoactive Proteins

Vanderbilt University, Nashville TN

Investigators

Abstract

Non-Technical: This award to Vanderbilt and Tennessee State Universities will explore fundamental advances in the integration of proteins into devices to speed the development of biohybrid solar cells for the generation of affordable, renewable power. A team of two chemists, and a chemical engineer will collaborate in this project to develop nature-inspired solar cells that use proteins from green plants as the photo-active elements. The protein complexes Photosystem I (PSI) and Photosystem II (PSII) drive photosynthesis in plants and are highly efficient solar converters. Members of this team have experience in integrating PSI and PSII films with electrode surfaces to design and construct photoelectrochemical cells with photocurrents that have improved by a factor of nearly 106 over the past five years and are now within an order of magnitude of many mature technologies. This research project will address key fundamental biomaterials issues to greatly enhance the performance of photosystem-based solar cells. The research team for this project will build on their strong track record of integrating research with education at Vanderbilt and Tennessee State University, an HBCU, by promoting the interdisciplinary education of graduate and undergraduate researchers in engineering and chemistry through research experiences and interdisciplinary coursework. An established outreach program to include students from under-represented groups through Fisk and Tennessee State HBCUs is combined with K-12 classroom outreach in the Vanderbilt Summer Academy and Vanderbilt Student Volunteers for Science. Technical: In this project, the team from Vanderbilt and Tennessee State will develop a biomimetic approach to orient PSI on electrode surfaces, explore new ways of interfacing these proteins with conductive materials to facilitate electron flow to/from the proteins, and promote band energy alignment with the goal to achieve another quantum leap in biohybrid solar energy conversion. First, PSI orientation at electrode surfaces will be greatly enhanced by selectively modifying the exposed stromal face of PSI within the thylakoid membrane with surface-active ligands before releasing the modified protein for directed assembly onto surfaces. Achieving uniform orientations of these biomolecular photodiodes without the reliance on expensive and slow alternative methods would greatly advance biohybrid performance. Second, the conductivity within PSI films will be promoted by wiring reduced graphene oxide, redox polymers, and semiconductor nanoparticles to the active PSI sites. These oriented and more conductive PSI films will be interfaced with two types of electrode systems in both wet and solid-state systems. Building from the group's recent success, PSI films will be interfaced with semiconductors with appropriate energy levels to guide electron flow unidirectionally through the circuit. In addition, an all-carbon-based solar cell in which PSI films are sandwiched between oppositely doped, atomically thin graphene sheets to yield "stacked" architectures with only slight impedance of incoming light will be designed, fabricated, and optimized. These advances will also be applied to the interfacing and photoelectrochemistry of PSII onto substrate electrodes. The PIs will create outreach components and kits for building and demonstrating these devices in the middle school and high school settings.