Publications

DOE/BES/NSET annual report on growth of metal and semiconductor nanostructures using localized photocatalysts

Shelnutt, John A.; Brinker, C.J.; Van Swol, Frank; Haddad, Raid E.; Shelnutt, John A.; Medforth, Craig J.; Pereira, Eulalia P.; Singh, Anup K.

Our overall goal is to understand and develop a novel light-driven approach to the controlled growth of unique metal and semiconductor nanostructures and nanomaterials. In this photochemical process, bio-inspired porphyrin-based photocatalysts reduce metal salts in aqueous solutions at ambient temperatures to provide metal nucleation and growth centers. Photocatalyst molecules are pre-positioned at the nanoscale to control the location and morphology of the metal nanostructures grown. Self-assembly, chemical confinement, and molecular templating are some of the methods used for nanoscale positioning of the photocatalyst molecules. When exposed to light, the photocatalyst molecule repeatedly reduces metal ions from solution, leading to deposition and the synthesis of the new nanostructures and nanostructured materials. Studies of the photocatalytic growth process and the resulting nanostructures address a number of fundamental biological, chemical, and environmental issues and draw on the combined nanoscience characterization and multi-scale simulation capabilities of the new DOE Center for Integrated Nanotechnologies, the University of New Mexico, and Sandia National Laboratories. Our main goals are to elucidate the processes involved in the photocatalytic growth of metal nanomaterials and provide the scientific basis for controlled synthesis. The nanomaterials resulting from these studies have applications in nanoelectronics, photonics, sensors, catalysis, and micromechanical systems. The proposed nanoscience concentrates on three thematic research areas: (1) the creation of nanoscale structures for realizing novel phenomena and quantum control, (2) understanding nanoscale processes in the environment, and (3) the development and use of multi-scale, multi-phenomena theory and simulation. Our goals for FY03 have been to understand the role of photocatalysis in the synthesis of dendritic platinum nanostructures grown from aqueous surfactant solutions under ambient conditions. The research is expected to lead to highly nanoengineered materials for catalysis mediated by platinum, palladium, and potentially other catalytically important metals. The nanostructures made also have potential applications in nanoelectronics, nanophotonics, and nanomagnetic systems. We also expect to develop a fundamental understanding of the uses and limitations of biomimetic photocatalysis as a means of producing metal and semiconductor nanostructures and nanomaterials. The work has already led to a relationship with InfraSUR LLC, a small business that is developing our photocatalytic metal reduction processes for environmental remediation. This work also contributes to science education at a predominantly Hispanic and Native American university.