Solar-active photocatalytic tandems. A compromise in the photocatalytic processes design

The paper presents a three-layered tandem system of SnO2/CuxS/TiO2, and proves its activity under artificial solar radiation in the phenol photodegradation. The effect of pH (3-9) is comparatively analysed considering the electrostatic interactions substrate - pollutant (based on pzc and pKa), the speciation of the oxidative species (particularly the pH-dependent equilibria) and the photocatalyst stability, evaluated based on changes in surface morphology and optical transmittance. The results show the need to optimize the photocatalytic process design with a compromise between the electrostatic attraction and the photo-corrosion conditions and outlines the neutral pH as best meeting the efficiency and stability prerequisites.