Carbon dots-initiated luminol chemiluminescence in the absence of added oxidant

This paper reports for the first time the chemiluminescence (CL) of luminol in the absence of added oxidant with carbon dots (CDs) as the catalyst. By means of CL spectra, UV–vis spectra, electron spin resonance spectra, Fourier transform infrared and X-ray photoelectron spectra, the possible CL reaction mechanism is proposed. The CL luminophor was still 3-aminophthalate, the CL enhancement of luminol system was supposed to originate from the intrinsic catalytic activity of CDs, which can efficiently catalyze the decomposition of dissolved oxygen to generate superoxide radical anion in luminol solution. Then, the resulting superoxide radical anion reacted with luminol to cause CL emission. Furthermore, the effects of size and surface states on the catalytic activity of CDs were investigated. The results suggested that the catalytic activity of CDs are mainly affected by the surface states, and the size of CDs display little influence on the catalytic activity of CDs. Therefore, the catalytic activity of CDs can be tuned by modulating functional groups on the surface of CDs, which sheds new light on the characteristic of CDs.