ABSTRACT
Yolk-shell (Y-S) structured Fe3O4@void@CdS nanoparticles (NPs) are synthesized through a one-pot coating-etching process with Fe3O4@SiO2 as the core, where the coating of an outer CdS shell from a chemical bath deposition (CBD) process is simultaneously accompanied by the gradual etching of an inner SiO2 shell. The as-prepared Fe3O4@void@CdS NPs (ca. 200 nm) possess good monodispersity and a uniform CdS shell of ca.15 nm. This composite exhibits excellent photo-Fenton (ph-F) activity toward the degradation of methylene blue (MB) in a wide pH working range of 4.5-11 under the visible light irradiation. A series of control experiments demonstrate the unique Y-S structure contributes to the enhanced activity, where the separation of hole-electron pair from CdS and the reduction of Fe(2+) from Fe(3+) are mutually promoted. The similar efficiency can also be achieved when the shell component changes to TiO2 or CeO2, demonstrating a general strategy for the design of robust ph-F agent.
ABSTRACT
Highly sensitive surface-enhanced Raman scattering (SERS) detection was achieved on plasmon-free TiO2 photonic artificial microarray, which can be quickly recovered under simulated solar light irradiation and repeatedly used. The sensitive detection performance is attributed to the enhanced matter-light interaction through repeated and multiple light scattering in photonic microarray. Moreover, the SERS sensitivity is unprecedentedly found to be dependent on the different light-coupling performance of microarray with various photonic band gaps, where microarray with band gap center near to laser wavelength shows a lower SERS signal due to depressed light propagation, while those with band gap edges near to laser wavelength show higher sensitivity due to slow light effect.
