Rapid Screening of Oxygen States in Carbon Quantum Dots by Chemiluminescence Probe

The oxygen states (O-states) of carbon quantum dots (CDs) play an important role, with regard to their optical properties and analytical applications. However, the rapid screening of O-states in CDs is still a great challenge, because of the complicated surface composition. In this study, it is found that the chemiluminescence (CL) intensity of prepared CDs in the presence of peroxynitrite (ONOO^-) is proportional to the content of C-O group-related O-states. The related mechanism discloses that the O-state-dependent CL is due to the fact that abundant C-O functional groups in CDs with high O-states could facilitate the electron transfer of the produced smaller energy gaps for strong CL emission. Hence, ONOO^--induced CL can be utilized as a facile probe for the rapid screening of O-states in CDs with some advantages, such as rapid response, low cost, and easy operation. Its practicability is verified by detecting the CL of phosphorus-doped CDs with variable phosphorus-doping contents. The content of C-O group-related O-states in sulfur-/phosphorus-doped CDs measured by the proposed CL probe is consistent with X-ray photoelectron spectroscopy (XPS) characterization. This strategy can also be extended to distinguish O-states in different types of nanoparticles by tuning the CL probe molecules.