Chemiluminescence Arising from the Decomposition of Peroxymonocarbonate and Enhanced by CdTe Quantum Dots

CdTe quantum dots (QDs) capped with mercaptoacetic acid were applied to the hydrogen peroxide-sodium hydrogen carbonate chemiluminescence (CL) system. The CL emission intensity was significantly enhanced by different sizes of CdTe QDs. Peroxymonocarbonate (HCO4-) was formed in the reaction of hydrogen peroxide and sodium hydrogen carbonate, which was a reactive oxygen species. Decomposition of HCO4- generated superoxide ion radical (center dot O-2(-)) and hydroxide radical (center dot OH). The enhanced CL was induced by the excited CdTe QDs, which could be produced from the combination of hole (oxidized QDs (h(+))) and electron (reduced QDs (C)) injected QDs. Radical scavengers and organic reagents such as nitro blue tetrazolium chloride (NBT), cytochrome c, sodium azide, ascorbic acid, thiourea, tert-butanol, and dimethyl sulphoxide were used to study the emitting species. The intermediate hydroxide radical and superoxide ion were key species for producing hole and electron-injected QDs. Four emitters such as O-1(2), (O-2)(2)*, (CO2)(2)* and CdTe* were detected in the CL system. The mechanism was discussed based on the CL emission spectra, electron spin resonance spectra, fluorescence spectra, and UV-vis absorption spectra. The CL properties of CdTe QDs will be helpful to study semiconductor nanocrystals and will open new avenues for the application of QDs in many fields, such as chemistry, biology, microbiology, and biochemistry.