Effects of localized surface plasmon resonance of Ag nanoparticles on luminescence of carbon dots with blue, green and yellow emission

摘要

We disclose the effects of localized surface plasmon resonance (LSPR) of Ag nanoparticles (NPs) on luminescence properties of carbon dots (CDs) with blue, green and yellow emission, respectively. The Ag NPs without coating layer result in fluorescence quenching of CDs with blue, green and yellow emissions. The Ag NPs coated with SiO2 layer only quench the blue emitting CDs (B-CDs) since the overlap of emission and LSPR absorption of Ag NPs. However, the fluorescence enhancement of CDs with green (G-CDs) and yellow emission (Y-CDs) can be realized by adjusting the size of the Ag NPs and the distance between Ag NPs and CDs via silica coating (Ag@SiO2). The luminescence intensity of G-CDs and Y-CDs can be improved 5-6 times as the coating thickness of SiO2 is 15 nm. Fluorescence quenching and enhancement mechanism can be clarified by the electron transition and energy transfer process between CDs and Ag NPs, which provides guidance principle for LSPR enhanced fluorescence.