Controlled Preparation of Uniform TiO2-Catalyzed Silver Nanoparticle Films for Surface-Enhanced Raman Scattering

Abstract

Silver nanoparticle (AgNP) film is a kind of useful material in biochemical and biomedical fields as it can be used as a sensor based on its surface plasmon resonance for surface enhanced Raman scattering (SERS) analysis. In this work, a uniform AgNP film with controlled nanoparticle size, shape, and density have been prepared on TiO2 film in a AgNO3 solution by photocatalysis reduction method. The influences of TiO2 film thickness and morphology on the AgNP’s growth have been systemically studied. It is found that a thicker TiO2 film with nanocrystalline morphology leads to a higher AgNP’s growth rate, while a thinner TiO2 film with membrane morphology leads to a lower AgNP’s growth rate. Experimental SERS results show that the AgNP film prepared with different TiO2 films and ultraviolet light irradiation time exhibit different SERS signals of rhodamine 6G (10–6 M). Atomic force microscope and scanning electron microscope analysis reveal that the size effect is a key factor affecting the SERS of our prepared AgNP films, which has also been evaluated by finite-difference time-domain simulation. It is found that the larger the average AgNP’s size (≤λ/4) and roughness, the higher the Raman enhancement. The SERS mapping images exhibit a good uniform Raman enhanced results in our prepared TiO2-catalyzed AgNP film with a low relative standard deviation of approximately 10%.