Improved SERS Sensitivity on Plasmon-Free TiO₂ Photonic Microarray by Enhancing Light-Matter Coupling

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

Synthesis of Yolk–Shell Structured Fe₃O₄@void@CdS Nanoparticles: A General and Effective Structure Design for Photo-Fenton Reaction

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 Fe²⁺ from Fe³⁺ 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