Maximization of photocatalytic activity of Bi2S3/TiO2/Au ternary heterostructures by proper epitaxy formation and plasmonic sensitization

Ternary Bi2S3/Tio(2)/Au heterostructure has been successfully synthesized by decorationg Au nanoparticls onto binary Bi2S3/Tio(2) heterostructure. Structural analysis suggests that the heterostructure consists of orthorhombic Bi2S3, tetragonal anatase TiO2 and face centered cubic Au. The appearance of extra Raman peak at 123 cm(-1) and the modification of Raman peaks of Bi2S3 and TiO2 phases indicates a significant molecular interaction during growth of TiO2 nanocrystals (NCs) on the surface of Bi2S3 nanorods. Self assembly of nanorods triggered by oleic acid results in urchin like morphology of pure Bi2S3. The {011} facet of TiO2 nano crystals grow epiaxially on {013} facet of Bi2S3 nanorods. Periodic arrangement of (111) plane of Au and (011) plane of Bi2S3 favors epitaxial growth in Bi2S3/TiO2/Au heterostructure. Unique design of the ternary heterostructure makes a preferable pathway for the photogenerated electrons by suppressing the electron-hole recombination. The observation of decreased electron spin resonance signal intensity based on spin label technique confirms the electron transfer from photoexcited heterostructure. Favorable energetic positions of conduction and valence band edges of semiconductors (Bi2S3 and TiO2) and Fermi level of metal (Au) are the key factors to enhance the photo catalytic activity of ternary heterostructure. Plasmonic phenomenon of metal (Au) nanoparticles by changing their size and shape was also investigated to remove organic pollutants from waste water. (C) 2017 Elsevier B.V. All rights reserved.