Enhanced detection of nitrite ions over copper acetylacetonate/polymeric carbon nitride composites

Abstract

Nitrogen containing compounds such as nitrite ions (NO2 -) may cause contaminations to the environment, food and drinking water, and they have a negative effect on human health. In this study, a novel fluorescence sensor was developed by modification of polymeric carbon nitride (CN) with copper(II) acetylacetonate (Cu(acac)2). The polymeric CN was prepared by using urea as a precursor via thermal polymerization technique, while the Cu(acac)2 was introduced onto the polymeric CN via an impregnation method. The formation of polymeric CN can be confirmed from the Fourier transform infrared (FTIR) and the diffuse reflectance ultraviolet visible (DR UV-Vis) spectroscopies. The polymeric CN exhibited three excitation peaks at 277, 315, and 370 nm owing to the presence of CN, CO, and CN groups, respectively, while there was only one emission peak observed at 455 nm. The emission intensity was decreased with the increase of Cu(acac)2 loading, suggesting certain interactions between the polymeric CN and the added Cu(acac)2. The performances of the polymeric CN and Cu(acac)2/CN composites as fluorescence sensors were evaluated for (NO2 -) detection with concentration range of 0.5-4 μM. It was revealed that the CN sites in the polymeric CN were the most favored quenching sites for the (NO2 -). With the addition of Cu(acac)2 (0.1 mol%), the quenching rate for CN sites was enhanced two times higher than that of the polymeric CN. This study demonstrated that the composite is a promising fluorescence sensor for the detection of (NO2 -).