Visible-Light Photocatalyst CuO/SnO2/Ag: Synthesis, Performance Evaluation and Phytotoxicity Studies

Abstract

Nanocomposite photocatalysts are promising for removing pollutants from wastewater. Despite intensive studies, less attention is paid to toxicity of nanocomposites. In our work, we have obtained a new hetero-photocatalyst based on nanostructured CuO (1.5 μm), decorated with Ag (100 nm) and low crystallinity SnO₂. The composition and morphology were studied by XRD, SEM, EDX and AFM. The photocatalytic decomposition of the methyl orange under natural sunlight was investigated. About 84% of the dye decomposed in 120 min, in contrast to unmodified CuO (only 50%). The mechanism of photocatalysis is proposed. The degradation process corresponded to the pseudo-first order kinetics. A decrease in the optical band gap of the nanocomposite compared to unmodified CuO was noted. The nanocomposite efficiency associated with the surface increasing and the heterojunction formation. The phytotoxic effect on the aquatic plant Ceratophyllum demersum was studied. A decrease in phytotoxicity in contrast to the initial CuO was established. The nanocomposite provided a stimulating effect on the chlorophyll a concentration. The results expand the knowledge about the phytotoxicity of photocatalytic nanocomposites.