Acetaldehyde dynamics on TiO₂ surfaces

In photocatalysis, the interfacial charge transfer across a solid/gas interface to a surface bound species requires the initial adsorption of reactants. A particular set of reactions, photo-oxidation of organic compounds by semiconductors are of significant relevance in environmental remediation applications and air purification technologies. At the surface, these species can be bound in several conformations and also undergo thermally catalyzed reactions. By using Chemical Ionization Mass Spectrometry (CIMS) to study the adsorption properties of acetaldehyde on TiO₂ of different morphologies, we resolve the kinetics of acetaldehyde at the surface for its adsorption on reversibly and irreversibly bound sites as well as the chemical reaction that takes place. The pressure dependence is explored and complemented with FT-IR spectroscopy to reveal the surface species formed. A detailed understanding of the dynamics of organics at the surface of photocatalysts is necessary to explain their photocatalytic activity.