The Chemical Catalysis Program supports Professors Thomas Spiro, David Baker, Daniel R. Gamelin, and Christine K. Luscombe, all of the University of Washington, who seek support for research on the creation of metallo-macrocycle-protein constructs as novel photocatalysts for H2 production from water. The central idea of this project is to combine photon capture and H2 production into a single chemical assembly. This proposal brings together the key design elements needed to produce an effective H2-evolving solar photocathode. Progress toward the goal of efficient H2 photoproduction will provide more in-depth understanding of photoelectrochemistry and catalysis. Both topics are of intense current interest, but are generally studied separately. Should the project succeed, it will bring both scientific and practical dividends. Water splitting is a major scientific focus for the future, and these results will garner wide interest.
With the support of the Chemical Catalysis Program, Professors Thomas Spiro, David Baker, Daniel R. Gamelin, and Christine K. Luscombe, all of the University of Washington (UW), will perform research on a project that may point the way toward efficient and inexpensive photocatalysts, which could play a significant role in the development of a solar-hydrogen economy. This work is motivated by the urgency of developing new and clean sources of energy. The capture and conversion of sunlight can meet a major fraction of future human energy needs; however, energy storage and conversion to transportation fuels pose major challenges. Broader impacts include communicating with the public through participation in the University of Washington's CLEAN ENERGY initiative, which maintains a website and runs conferences and workshops for energy stakeholders. The PIs will also participate in Seattle's Pacific Science Center outreach activities. In addition, the general public will be recruited to contribute to the protein design aspects of the project through the popular fold.it (http://fold.it) on-line computer game developed by the Baker group and collaborators. They will also participate in the successful high-school outreach program run by the NSF Center for Enabling New Technologies through Catalysis, housed at UW, which also provides us a mechanism for recruiting minority undergraduates to their laboratories.
This project was motivated by the urgency of developing new and clean sources of energy. Sunlight can meet a major fraction of future human energy needs if it can be efficiently converted to useful forms of energy; conversion to chemical fuels is especially desirable, to meet transport and energy storage needs. Hydrogen from water represents an abundant resource, if solar energy can be used to drive the water splitting reaction. This project was undertaken to point the way toward efficient and inexpensive, based on relatively abundant metals, photocatalysts for hydrogen production. The objective of this research was to establish the feasibility of creating an integrated system for proton photoreduction using protein-functionalized metallomacrocycles. The constructs are based on metal complexes, metalloporphyrins, that efficiently absorb solar photons and then channel the energy into the separation of charge; the electron ends up on the metal ion, which is then capable of generating hydrogen from water. To ensure successful proton reduction, the constructs were envisioned to have small protein scaffolds that bind the macrocycle and deliver protons to the photoreduced metal center, thereby inducing the catalytic reaction. Much has been learned during the course of the awarded project. Different strategies for the protein structures to bind metallomacrocycles were explored, which led to promising protein designs. In one approach, the porphyrin-peptide constructs were crowd-source-designed via the protein folding online computer game Foldit, which recruits the general public to play and compete to design new protein functions. A puzzle to design a protein that would strategically fold around the macrocycle catalyst was introduced to the players of the fold.it game, allowing the general public to directly contribute to the project, and increasing awareness of approaches to capture solar energy, educating the players on basic principles of solar hydrogen production. A new ultrafast Raman spectroscopy–based technique was developed and applied to a model photocatalyst, in order to structurally characterize processes occurring on the ultrafast time scale after the photon absorption event. This work laid the foundation for further application of this technique to other ultrafast processes in solar energy research. Electrochemical and spectroscopic experiments and peptide modeling and synthetic efforts, performed during the course of the project, assessed feasibility and addressed significant scientific issues, providing the groundwork for future research. Under this project, several early career scientists were trained in an interdisciplinary setting to collaboratively tackle major scientific challenges in global energy supply and utilization. The interdisciplinary nature of the project enhanced their experience by broadening their scientific perspective and fostering a collaborative spirit.
