Particle-arrayed silver mesocubes synthesized via reducing silver oxide mesocrystals for surface-enhanced raman spectroscopy

In this study, we demonstrate an easy particle-mediated protocol using the specific structure of mesocrystal Ag₂O sacrificial templates to synthesize highly rough-cubic Ag mesocages. To the best of our knowledge, the mesocrystal particles are reported for the first time as sacrificial templates for synthesizing metal particles. The obtained Ag mesocages show high surface-enhanced Raman scattering (SERS) sensitivity because of the highly rough topography formed by arrays of uniform individual Ag nanoparticles. Abundant "hot spots" with greatly enhanced local electromagnetic field are promoted densely on the mesocage surface by the plenty of deep and narrow gaps and the hollow structure. The single-particle SERS signal generated by the Ag mesocage has an enhancement factor of approximately 10⁹, which is approximately four times higher than the Ag mesocage synthesized using single-crystal Ag₂O particle as a template. Meanwhile, this signal displays a linear dependence on the detected analyte concentration, sensitively down to 1.0 × 10^-12 m. Mesocrystal particles are developed for the first time as a sacrificial template to synthesize metal mesocages and porous mesoparticles. The obtained highly rough Ag mesocages show high sensitivity for enhanced Raman spectroscopy because of the abundance of narrow and deep nanogaps formed by the array of uniform Ag nanoparticles on the shell.