Surface-Enhanced Raman Scattering Activity of ZrO(2) Nanoparticles: Effect of Tetragonal and Monoclinic Phases

The effect of the ZrO(2) crystal form on surface-enhanced Raman scattering (SERS) activity was studied. The ratio of the tetragonal (T) and monoclinic (M) phases of ZrO(2) nanoparticles (ZrO(2) NPs) was controlled by regulating the ratio of two types of additives in the hydrothermal synthesis method. The SERS intensity of 4-mercaptobenzoic acid (4–MBA) was gradually enhanced by changing the M and T phase ratio in ZrO(2) NPs. The degree of charge transfer (CT) in the enhanced 4–MBA molecule was greater than 0.5, indicating that CT was the main contributor to SERS. The intensity of SERS was strongest when the ratio of the T crystal phase in ZrO(2) was 99.7%, and the enhancement factor reached 2.21 × 10(4). More importantly, the proposed study indicated that the T and M phases of the ZrO(2) NPs affected the SERS enhancement. This study provides a new approach for developing high-quality SERS substrates and improving the transmission efficiency of molecular sensors.