Fluorescence Properties of ZnOQDs-GO-g-C3N4 Nanocomposites

Abstract

In this paper, the fluorescence properties of ZnOQD-GO-g-C₃N₄ composite materials (ZCGQDs) were studied. Firstly, the addition of a silane coupling agent (APTES) in the synthesis process was explored, and it was found that the addition of 0.04 g·mL^-1 APTES had the largest relative fluorescence intensity and the highest quenching efficiency. The selectivity of ZCGQDs for metal ions was also investigated, and it was found that ZCGQDs showed good selectivity for Cu²⁺. ZCGQDs were optimally mixed with Cu²⁺ for 15 min. ZCGQDs also had good anti-interference capability toward Cu²⁺. There was a linear relationship between the concentration of Cu²⁺ and the fluorescence intensity of ZCGQDs in the range of 1~100 µM. The regression equation was found to be F₀/F = 0.9687 + 0.12343C. The detection limit of Cu²⁺ was about 1.74 μM. The quenching mechanism was also analyzed.

Keywords: fluorescence probe; fluorescence properties; metal ion; nanocomposites.

Figure 1

(a) Fluorescence emission spectra of ZCGQDs; (b) relative fluorescence intensity with the addition of 20 µM Cu²⁺ to ZCGQDs.

Figure 2

The plot of relative fluorescence intensity versus time.

Figure 3

(a) Fluorescence spectra of the different heavy metal ions added; (b) relative fluorescence intensity of the different heavy metal ions added.

Figure 4

Relative fluorescence intensity of ZCGQDs in the coexistence of Cu²⁺ with other metal ions.

Figure 5

(a) Fluorescence spectra of different concentrations of Cu²⁺; (b) fitted curve of the linear relationship.

Figure 6

(a) HRTEM image of ZCGQDs; (b) HRTEM image of ZCGQDs after Cu²⁺ was added.

Figure 7

UV–vis absorption spectra of mixed colloids.