Environmentally friendly InP quantum dots as a visible-light catalyst for water treatment

In this study, we demonstrate the first successful application of InP quantum dots (QDs) as an environmentally friendly visible light photocatalyst for water treatment. The QDs were synthesized using a hot injection method followed by a surface ligand exchange with sulphide ions (S2-) to render them water-dispersible. The photocatalytic activity of the QDs was assessed by examining their ability to degrade two common water contaminants: caffeic acid (CA) and 4-hydroxyphenylacetic acid (4-HPA) under visible light irradiation. After 4 hours of irradiation, 60% of CA was removed as compared to 30% of 4-HPA. In contrast, no significant degradation was observed using TiO2. The decomposition kinetics of CA was further studied and was found to follow a first order kinetic model.