Directing Electron Flow and Intermediate Species to Catalytically Active Sites in Engineered Metal/Semiconductor Nanostructures
Abstract
We investigate carefully engineered metal/semiconductor nanostructures based on TiO2-passivated III-V compound semiconductors (i.e., GaP, InP, GaAs) to control the flow of electrons and intermediate species to catalytically active sites. The TiO2 passivation layer prevents photocorrosion of the III-V compound surface, providing a viable, long-term stable photocatalyst. Our primary reactions of interest include water splitting and the photocatalytic reduction of CO2 with H2O to various hydrocarbons, which is a complex reaction system requiring up to 8 electrons and many intermediate species, some of which have extremely high energy barriers. This system provides an interesting testbed for studying the control of energy transfer in catalytic processes. These carefully engineered structures provide control over the electron (hole) energy landscape, directing the flow of electrons to catalytically active sites through built-in fields, arising from a pn-junction formed between the III-V compound semiconductor and TiO2 passivation layer. These structures also enable us to control the adsorption/desorption kinetics ofreactant, intermediates, and products to ensure that a high density of intermediates are present at the catalytically active sites. We use vibrational sum frequency generation (vSFG) spectroscopy to identify reaction intermediate species and catalytically active sites on these photocatalytic surfaces. In order to explore and separate various mechanisms of catalysis and enhancement, we will perform a systematic study of sample morphology by varying the surface coverage, size, and shape of metal co-catalyst nanoparticles, and controllably introducing defects to determine their effect on the reaction surface-bound intermediates.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 2019
- Accession Number
- AD1096621
Entities
People
- Stephen B Cronin
Organizations
- University of Southern California