High-throughput Photocatalytic Reactor With in Operando Characterisation for Fast Screening of Materials for the Photodegradation of Water-Borne Pollutants

A novel fast-screening photocatalytic reactor system (FaS-PhoReS) using simulated terrestrial sunlight is conceived and demonstrated. The instrument is capable of screening, automated data measurement and recording 32 samples at once with no external characterisation devices (e.g., spectrophotometer) required. The capabilities of the system are validated in operando via i) photolysis tests of 12 water-soluble organic dyes to investigate the photostability under simulated sunlight; and ii) photocatalytic degradation of the four most photostable dyes – methylene orange, tartrazine 85, rhodamine B and direct black 38 identified from the photolysis results – using TiO₂ thin films prepared by atomic layer deposition. The applicability of the instrument is also demonstrated: i) using alternate photocatalysts – ZnO films and TiO₂ nano-powders; and ii) for the in situ detection of reactive oxygen species. The findings indicate that FaS-PhoReS exhibits consistent and repeatable results without being affected by factors such as i) non-uniformity of light intensity; ii) temperature and humidity; and iii) artefacts due to evaporation of the dye solution. Methylene orange and tartrazine 85 dyes are chosen to evaluate photocatalytic degradation, TiO₂ thin films annealed at 500 to 600 °C and TiO₂ nano-powders of 0.1 to 0.3 mg exhibiting better performance.