Enhanced visible-light-driven photocatalytic activity of Au@Ag core-shell bimetallic nanoparticles immobilized on electrospun TiO2 nanofibers for degradation of organic compounds

In this work, Au@Ag core-shell nanoparticles (NPs) with variable Ag shell thickness were synthesized and immobilized on TiO2 nanofibers (TNF). Further, the photocatalytic activity of such TNF was demonstrated using methylene blue (MB) dye as a model pollutant. Transmission electron microscopy (TEM) and the shift of surface plasmon resonance (SPR) absorption confirmed the formation of Au@Ag core-shell NPs. The Ag shell layer suppressed the defect related emission of TNF and significantly enhanced the charge separation at the interface. The photocatalytic activity of Au@TNF and Au@Ag@TNF was assessed by the degradation of MB dye under ultraviolet (UV) and solar light irradiation. Compared to the TNF and Au@TNF, Au@Ag@TNF revealed efficient photocatalytic activity attributable to the presence of two SPR generated hot electrons from the excited Au core and Ag shell under solar light irradiation. The photocatalytic activity of the Au@Ag@TNF was decreased with the increase in Ag shell thickness. The Au@Ag@TNF core-shell photocatalyst showed similar to 3 times higher photocatalytic activity than TNF under solar light irradiation. The recyclability results showed a slight reduction (similar to 18%) in the photocatalytic performance of Au@Ag@TNF after carrying out five consecutive runs of photodegradation of MB dye. Such NPs immobilized on TNF are thus a promising platform for the development of photocatalytic wastewater treatment and other applications such as sensing, photovoltaics and photocatalytic water splitting.