Molecular Interfaces to Single-crystal Anatase Surfaces:
Surface Chemistry and Impact on Charge Dynamics
EMSL Project ID
39998
Abstract
The anatase form of TiO2 is of great interest as a substrate for a variety of photochemical and photoelectrochemical pathways for solar-to-electrical and solar-to-fuel conversion. The resulting charge separation can be used to generate an electrical current or to induce catalytic oxidation reactions, depending on the nature of the molecular complex. The integration of TiO2 with the unique chemical properties of molecular catalysts could lead to significant increases in efficiency of solar-to-electrical and solar-to-fuel conversion. However, the nature of the ligand-to-TiO2 charge transfer process remains poorly understood. Numerous studies have shown that the (001) surface of TiO2 in the anatase crystal form is the most active form for both photocatalysis and photovoltaic energy conversion, but this face is not easily formed under typical growth conditions. Researchers at EMSL have developed methods for growing thin films of anatase(001). The primary goal of the proposed research is to investigate the use of molecular monolayers as highly tunable interfaces between anatase TiO2 and organic molecules relevant to photovoltaic energy conversion and photocatalysis. In this proposed research, the Hamers group at Wisconsin will team with team with EMSL scientists to investigate new strategies for interfacing organic molecules with single-crystal anatase, and to characterize how different surface functionalization strategies affect charge-carrier dynamics. Experiments will be conducted on single-crystal anatase to achieve a fundamental understanding of the molecular interfaces and how the molecular interfaces affect electron-transfer properties through the layers. In the proposed research, we will use XPS and FTIR to characterize the chemistry of the molecule-anatase interface. Time-resolved microwave conductivity and other optical measurements will be used to characterize the dynamics of charge carriers. Charge dynamics on ultrafast time scales will be achieved through a collaboration with Martin Zanni's group to explore charge transfer to anatase on femtosecond time scales, providing fundamental insights into the fastest charge transfer processes relevant to efficient conversion of optical energy into chemical and electrical energy.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2010-10-01
End Date
2011-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members