The World is facing major environment pollution due to rapid industrialized growth, which is governed by the increase in demand of products with continuous growth of population. Environmental hazards affect the serious health issue for human, aquatic and animal as well. Photocatalysis is a prominent process to degrade water and air pollutant such as methylene blue (MB), methyl orange, acetone, benzene etc. TiO2 has been mostly used photocatalyst due to low cost, chemical stability, resistant to corrosion etc., while it is active in UV light due to wide bandgap semiconductor. Metal nanoparticles have surface plasmon resonance (SPR) absorption in visible range, result in the improved optical property. Nanoparticles have tendency to form agglomerates, while this problem can be resolved by one-dimensional nanofibers and also this structure provides unidirectional path for photogenerated electrons, results suppression of excitons recombination. Here, we synthesized Au@Ag core-shell nanoparticles (NPs) with variable Ag shell thickness, later immobilized them on electrospun TiO2 nanofibers (TNF). Further, photocatalytic activity of TNF and different Au@Ag@TNF were demonstrated using MB dye as a model pollutant. The Au@Ag core-shell NPs were characterized by the transmission electron microscopy (TEM) and UV-vis spectra, a shift in the SPR absorption was observed. The Ag shell layer on Au@Ag@TNF reduced the defect related emission of TNF and significantly improves the charge separation at the Au@Ag and TNF interface. The photocatalytic activity of TNF, Au@TNF and Au@Ag@TNF was demonstrated for the degradation of MB dye under ultraviolet (UV) and solar light irradiation. Au@Ag@TNF showed higher photocatalytic activity due to the occurrence of two SPR generated hot electrons from excited Au core and Ag shell under solar light irradiance in compare to the TNF and Au@TNF. Au@Ag@TNF core-shell photocatalyst showed ~3 times higher reaction rate constant than TNF under solar light. The Au@Ag@TNF showed ∼18% reduction in the photocatalytic activity after five consecutive cycles. Morphology and crystallinity of Au@Ag@TNF did not significantly change after 5 cycles. Au@Ag core-shell NPs immobilized TNF are thus a promising materials for photocatalytic wastewater treatment and can be used in other applications such as photovoltaics and photocatalytic water splitting.

Effect of Ag shell thickness on photocatalytic degradation of organic compounds using Au@Ag core-shell bimetallic nanoparticles immobilized on electrospun TiO2 nanofibers

253rd National Meeting (2017)

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