In situ SERS monitoring of photocatalytic organic decomposition using recyclable TiO₂-coated Ag nanowire arrays

Recently, semiconductor and noble metal complex nanomaterials have attracted ever-increasing attention because of the realization of multiple functionalities in a single entity. In this study, Ag-TiO₂ core-shell nanocomposites were synthesized by hydrolysis of butyl titanate on the surface of Ag nanowires. Due to efficient electron transfer at the Ag-TiO₂ interface, the as-prepared nanocomposites exhibit much higher photocatalytic activity than bare TiO₂ films, as demonstrated by the enhanced photodegradation rate of R6G and methyl blue molecules. In the meanwhile, such nanocomposites serve as a high-sensitivity surface-enhanced Raman scattering (SERS) substrate for in situ monitoring of the photocatalytic decomposition reaction, and the substrate is recyclable due to its self-cleaning function. Full-wave numerical calculations reveal that the improved photocatalysis and SERS efficiencies are attributed to the largely enhanced electromagnetic near-field in the nanocomposites. Our results point out that bifunctional semiconductor-metal hybrids hold great promise for simultaneously detecting and decomposing organic pollutants in the environment.