Photocatalysis with hybrid co-coated WS₂ nanotubes

Inorganic fullerene-like (IF) nanoparticles (NP) and inorganic nanotubes (INT) of layered compounds, such as WS₂, have been of particular interest due to their unique structural characteristics. Recently, the catalytic decomposition of thiophene using INT of WS₂ decorated with Co NP was demonstrated. This finding also suggests that these materials could be also suitable for the photocatalytic treatment of pollutants in wastewaters. In the present work, the photocatalytic decomposition of methyl orange (MO) in aqueous solution using Co-coated INT-WS₂ as well as other NP was investigated. The photocatalytic reactivity under visible light illumination of this photocatalyst was measured and compared with that of various IF and INT and TiO₂ (P25). The Co NP-coated INT-WS₂ exhibited the highest photodegradation of MO among the studied NP. The significant enhancement in the photoactivity of the hybrid nanostructure can be attributed to the combination of the metallic Co NP and the semiconducting WS₂ nanotubes. The hybrid nanostructure enables the efficient light absorption by the INT and the subsequent charge separation of the hybrid semiconductormetal NP under visible light illumination. In addition, Raman spectroscopy technique was used to verify that the MO was decomposed by Co-coated nanotubes and not adsorbed in large amounts on the hybrid NP surface.