Task Descriptions

Center for Bio-Inspired Solar Fuel Production

Central to design of a complete system for solar water oxidation and hydrogen production is incorporation of synthetic components inspired by natural systems into one operational unit. The research effort of the Center is naturally divided into the following subtasks:

 

 

 

  • Subtask 1. Total systems analysis, assembly and testing  The solar water splitting device consists of four subsystems, each of which is being investigated by one of the four subtasks listed below. Combining the subsystems into an efficient, functional unit in the face of thermodynamic and kinetic constraints and emergent phenomena is one of the most intriguing aspects of the project. We know that this can be accomplished, because photosynthetic organisms have done so. Researchers working on other subtasks will be involved in assembling the final construct, but assembly can be best coordinated by scientists with a broad knowledge of energy flow and control in natural systems and experience in the limitations of artificial analogs.
  • Subtask 2. Water oxidation complex  This unit is the analog of the photosynthetic oxygen evolving complex, and will catalyze the oxidation of water to O2 and hydrogen ions. Given the difficulties researchers have encountered in developing a robust water oxidation catalyst based on abundant materials and having both low overpotential and high turnover, the Center is investigating several approaches to this part of the project. Researchers at ASU and elsewhere have uncovered the structure of the peptide framework of the natural PSII water oxidation complex, although the details of the metal complex itself and its mechanism of operation still await discovery. Our knowledge and expertise are now sufficient to allow construction of an artificial oxygen evolving complex whose catalytic site is based on the natural one. We are investigating a novel design wherein DNA is used as a self-assembling framework upon which a peptide-based catalyst is constructed. Another approach is based upon design of water soluble analogs of the natural water oxidation complex. In a collaborative project, a totally artificial porphyrin-based system whose design is drawn from the natural complex is being studied. A final approach involves investigating the structure, properties and function of a natural oxygen-consuming enzyme whose active site will be used as the basis for a new type of bioinspired water oxidation catalyst.
  • Subtask 3. Fuel production complex  The initial fuel production goal is hydrogen. The subunit responsible for this employs a de novo peptide based on the natural hydrogenase enzymes that organisms use for proton reduction. Electrons for this reduction will be provided by the artificial reaction center (Subtask #4). Because two electrons are required for hydrogen production, the fuel production complex will also contain a synthetic electron accumulator based on biological iron-sulfur proteins.
  • Subtask 4. Artificial reaction center-antenna complex This system consists of two main parts. One is an antenna system to collect light efficiently throughout the useable solar spectrum and transfer it to the other component, an artificial photosynthetic reaction center that uses excitation energy to initiate photoinduced electron transfer. The result is a pair of long-lived, energetic radical ions that will supply the redox energy necessary for water splitting. This unit will eventually incorporate photoprotective and photo-regulatory mechanisms to limit damage from excess solar light flux.
  • Subtask 5. Functional nanostructured transparent electrode materials  Requirements for the electrodes that bear the antenna-reaction center complexes and catalysts for hydrogen and oxygen production are a high surface area to serve as a binding site for these units, transparency, high electrical conductivity, specifically-tuned semiconductor properties, chemical inertness, and physical robustness. Meeting these requirements will necessitate new materials based on nanostructured metal oxides and other inorganic materials suitable for eventual inexpensive, large-scale fabrication.
Center for Bio-Inspired Solar Fuel Production 
Arizona State University, Room ISTB-5 101, Box 871604, Tempe, AZ 85287-1604 
phone: (480) 965-1548 | fax: (480) 965-5927 | Contact Us