Singlet Oxygen Involved Luminol Chemiluminescence Catalyzed by Graphene Oxide

Singlet oxygen (O-1(2)) in the chemiluminescence (CL) of luminol has been rarely involved. In this work, graphene oxide (GO) was prepared and at first found to enhance the CL of luminol-H2O2 system in a weakly alkaline medium mainly through the intermediate of O-1(2), which was greatly different from the traditional catalyst in such CL system that occurred in a strongly basic medium through the intermediates such as superoxide anion radical (O-2(center dot-)) and hydroxyl radical (OH center dot). With the aid of CL spectral, UV-visible absorption spectral, and electron spin resonance (ESR) spectral measurements and investigations on the effects of various free radical scavengers on the GO-enhanced luminol CL, we identified the acceleration role of GO played in the electron-transfer processes and efficient catalysis on the decomposition of H2O2, generating a high yield of O-1(2) on the surface of GO. The resulted O-1(2) then reacted with luminol, producing an endoperoxide, which decomposed to the excited-state 3-aminophthalate anions (3-APA*), giving rise to light emission with the maximum wavelength at 440 nm. As a result, this O-1(2)-induced luminol CL, owing to the catalysis by GO, could have six-fold enhancement compared with that in the absence of GO. These investigations could be further extended to the use of GO as an amplified label for the CL determinations of H2O2 and glucose. The significant features of this GO-catalyzed luminol CL may open up new opportunities for its potential applications in a wide range of fields.