Evaluation of photocatalytic activity of commercial red phosphorus towards the disinfection of E. coli and reduction of Cr (VI) under direct sunlight

Abstract

Elemental photocatalysts are getting the attention of material scientists as a new class of visible light photocatalysts in recent years. Hence it is important to understand and evaluate their phtocatalytic activity for the rationale design and development of new catalysts at low cost. In this regard, we choose commercial red phosphorus as elemental photocatalyst and we evaluate its activity towards the disinfection of E. coli and reduction of Cr (VI) under natural sunlight. The measured bandgap of red phosphorus is 2.0 eV matches with theoretical value and indicates the suitability of the material as photocatalyst under direct sunlight. Moreover, red phosphorus also has optimum valence and conduction band levels for the successful photo-generation of reactive oxygen species (ROS). These photogenerated ROS could help to achieve the disinfection of E. coli in 50 min. In the case of photocatalytic reduction of Cr (VI), 98% of Cr (VI) reduction has been achieved is in 60 min at pH 2. The rate of Cr (VI) reduction decreases with an increase in pH value similar to the reports with other metal oxide photocatalysts.