Hollow transition metal hydroxide octahedral microcages for single particle surface-enhanced Raman spectroscopy

Abstract

Semiconductor materials with roughened surfaces offer great advantages for surface enhanced Raman spectroscopy (SERS) based on a chemical enhancement mechanism. Herein, M(OH)_x (M = Fe, Co, Ni) hollow octahedral microcages are synthesized and explored as novel SERS-active substrates for sensitive dye molecule detection. A single as-prepared hollow M(OH)_x micro-octahedron particle with hierarchical surface architecture can be used as a highly sensitive SERS platform without interference from the surrounding environment. A comparative study indicates that Ni(OH)₂ microcages can provide optimal Raman enhancement of various dye molecules with an enhancement factor of up to 2.35 × 10³, due to stronger coupling interactions between the dye molecule and metal center, which greatly facilitate the electron transfer process. This work can expand the availability of SERS substrates with higher sensitivity and stability, and focus more attention on an in-depth understanding of chemical enhancement mechanisms.