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

Abstract

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 (HCO(4)(-)) was formed in the reaction of hydrogen peroxide and sodium hydrogen carbonate, which was a reactive oxygen species. Decomposition of HCO(4)(-) generated superoxide ion radical (·O(2)(-)) and hydroxide radical (·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 (e(-))) 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 (1)O(2), (O(2))(2)*, (CO(2))(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.

Quantum dot induced phototransformation of 2,4-dichlorophenol, and its subsequent chemiluminescence reaction

“…The other pathway involving superoxide radicals may also exist. The oxidation of RSH by dissolved oxygen can produce superoxide radicals, which then inject electrons into the 1Sh quantum-confined orbital of CdTe QDs, leading to the formation of the excited QDs * [9,15]. Upon returning to their ground states, the extra energy will be released in form of light at 550 nm.…”

“…Upon returning to their ground states, the extra energy will be released in form of light at 550 nm. Recombination of the superoxide radicals can form singlet oxygen molecular pairs ( 1 O 2 ) 2 * , which emit light in the wavelength range from 435 to 500 nm [9,15,31,37].…”

“…According to the CL energy match theory, the decrease in particle size will result in an increase in energy band gap, hence more energy is needed to form the excited QDs in the small diameter [16]. In contrast, when large diameter particles are used, the surface-to-volume ratio will decrease, which may reduce the area of QDs and thus the efficient electron transfer [15]. The CdTe QDs with the size of 2.69 nm and the concentration of 0.44 mg mL −1 was therefore used for subsequent experiment.…”

“…They have been widely applied to both fundamental research and sensing technologies [3][4][5][6]. Since the first work on the electrochemiluminescence (ECL) of silicon QDs was reported by Bard et al in 2002 [7], many other CL reactions mediated by QDs have also been studied in recent years [8][9][10][11][12][13][14][15].…”

Quantum dot-based photoelectric conversion for biosensing applications

“…Wider applications required development of a substitute for the physical light source. Chemiluminescence (CL) is a good substitute for the traditional physical light source [94][95][96][97][98][99]. By controlling the CL reaction conditions, emission with different wavelengths of light could be obtained for PEC detection free of a physical light source.…”