High-quality carbon dots: synthesis, peroxidase-like activity and their application in the detection of H2O2, Ag+ and Fe3+

In this paper, bright and high-quality carbon dots (CDs) were prepared by refluxing a membranous carbonized beta-cyclodextrin in nitric acid. The structure and optical properties of the CDs were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), fluorescence spectrophotometry (FL), X-ray diffraction (XRD) and Raman spectroscopy. The mechanism for the formation of the CDs is also discussed. As-prepared CDs could be used as peroxidase mimics for the detection of H2O2. The results indicate that the CDs are capable of rapid and sensitive detection of H2O2 in the linear range from 2 x 10(-6) to 5 x 10(-4) mol L-1 and the limit of detection of H2O2 is as low as 1 x 10(-6) mol L-1. More importantly, the peroxidase- like activity of the CDs is expanded to the detection of some oxidative ions ( such as Fe3+ and Ag+). The linear ranges for Fe3+ and Ag+ were 8 x 10(-6) to 1 x 10(-4) mol L-1 and 5 x 10(-6) to 1 x 10(-4) mol L-1 respectively, with corresponding detection limits of 8 x 10(-7) mol L-1 and 5 x 10-(7) mol L-1 respectively.