Title: Photocatalytic Applications of TIO2 For Catechol Degradation and α-FE2O3 for Carbon Dioxide Reduction

Abstract: Natural and anthropogenic processes are emitting organic and inorganic pollutants, such as phenolic compounds and carbon dioxide (CO₂), and polluting the atmosphere. In addition, to meet the energy demand of the world’s growing population, the use of nonrenewable fossil fuels is causing their depletion. Heterogenous semiconductor photocatalysis is a clean and low-cost methodology, which can simultaneously contribute to solve the above energy and environmental problems. In this work, photocatalytic degradation of catechol, an organic pollutant, is explored with Degussa P25 (mixed phase of titanium dioxide, TiO₂), and CO₂ reduction is accomplished with potassium doped iron oxide.

Degussa P25 is used to study the degradation of catechol at the air solid interface because of low cost, stability, and abundant sources of TiO₂. Catechol forms a chelate with TiO₂ and shows an absorption band in the visible range through ligand to metal charge transfer transition. The photocatalytic activity of catechol degradation on TiO₂ surface is reported at variable wavelength of irradiation. The generation and quantification of reactive oxygen species and redox pairs has been studied with scavengers. Finally, the apparent quantum efficiency (AQE) for catechol loss and CO₂ and carbon monoxide (CO) growths are determined.

Potassium doped iron oxides of varying composition (100 Fe:x K, 0 £ x £ 5) are synthesized using an incipient wetness impregnation method. The structure, composition, and properties of the catalysts are investigated by diffraction methods, thermal analysis, and multiple spectroscopies. UV-visible light excites the catalysts in the presence of pure CO₂ or air under a saturated water vapor atmosphere. The AQE for the CO(g) production shows maximum for 100 Fe:1 K catalyst.

The study creates a path for the application of semiconductor photocatalysis in air purification, water splitting, and fuel production.

Faculty Advisor: Dr. Marcelo Guzman