Photo-electrochemical PFAS oxidation for waste decomposition

After decades of successful application in products such as cookware, fire retardants, clothing and even cosmetics, the public and scientific opinion of perfluorocarbons has changed significantly. In recent years, the impact of PFAS on the environment and ourselves has been front page news on numerous occasions. Some members of this family of compounds have since been found to be carcinogenic or impacting hormone systems. Consequently, their once celebrated stability that led to the descriptive nickname "forever chemicals", pointing at their difficult breakdown and long-lasting presence in the environment, is now a point of immense concern.

Electrochemical oxidation of PFAS can play an important part in the breakdown of these pollutants in wastewater streams. This process, however, requires strong oxidizing species, such as ●OH or SO₄^●- radicals, which are generated from reactions involving highly reactive and aggressive compounds such as ozone and hydrogen peroxide. Environmental compatibility can be greatly improved by in situ generation of these reactive species on electrode surfaces, or as we propose here, by eliminating them entirely using direct oxidation of PFAS on UV photoanodes.

In this PhD project you will work on the photo-electrochemical oxidation of PFAS using direct oxidation on semiconductor electrodes under UV illumination. You will prepare and characterize novel thin-film TiO₂ electrodes using electrochemical and physical methods (sputtering, ALD). From photo-electrochemical and surface studies you will unravel reaction mechanisms for PFAS oxidation and build a fundamental understanding that will feed into improving the materials. By varying the stoichiometry, dopants and surface morphology you will gain insight into the relation between the material properties and their photo-electrocatalytic activity. After developing sufficiently active materials, you can further enhance their performance by depositing them on 3d-porous substrates to increase their surface area.

Through this research we will find pathways towards the optimal electrodes to degrade PFAS efficiently and in an environmentally responsible manner.