研究目的
Investigating the fluorescence antenna-sensitizing effect of graphene quantum dots (GQDs) on the detection of terbium ions.
研究成果
The as-prepared GQD was successfully synthesized by a one-step chemical oxidation method starting from the regular commercial multilayer graphene oxide (GO) via the refluxing in a concentrated mixture of strong acids. The fluorescence and the antenna-sensitizing effect of the resulting GQD in the case on the detection of terbium ions were studied. This study identified the significant antenna sensitization effect of the as-prepared GQD on the detection of the terbium ion solution in a high selectivity. The detectable linear range of the terbium ion concentration was found to be0-30 ×10-6 mol L-1 (R2=0.9960) in a detection limit of 0.3 ×10-6 mol L-1 , based on the optimal fluorescence wavelength at 546 nm at an excitation at 230 nm. Further mechanism studies verified the important participation of carboxyl function groups of the as-prepared GQD to the characteristic line-typed f-f transition derived fluorescence emission of the terbium ion.
研究不足
The study focused on the interaction of GQDs with terbium ions in aqueous media, and the potential interference from other rare earth elements was not extensively explored.
1：Experimental Design and Method Selection
A simple one-step chemical oxidation method was applied for the preparation of GQDs starting from the regular multilayer graphene oxide (GO) via the refluxing in a concentrated mixture of strong acids.
2：Sample Selection and Data Sources
Multilayer graphene oxide (GO) was purchased from Tan Feng Tech.inc. (China). The nitrate salts of 16 rare earth metal ions were purchased from the Aladdin Industrial Corporation.
3：List of Experimental Equipment and Materials
High-resolution transmission electron microscopic (HRTEM, JEM-2100 microscope), FTIR Prestige-21, X-ray photoelectron spectrometer (ESCALAB 250Xi X-ray photoelectron spectrometer), Smart Lab 9KW diffract meter, ZETASZER ZS90, Shimadzu UV 3600 spectrophotometer, Hitachi F-2500 (Japan).
4：Experimental Procedures and Operational Workflow
GQDs were synthesized by refluxing the commercial GO suspension in mixture of concentrated acids at the ambient condition. The solution was stirred at a temperature of 110°C for 24 hours in an oil bath. The solution was cooled and poured into a beaker with ultrapure ice water (800 mL). The pH of solution was adjusted to neutral (pH=7~8) with sodium hydroxide salts to neutralize the unreacted acids. The final product solution was filtered off using a 0.22 μm membrane filter to remove large or unreacted multilayer graphene oxide. The final product solution was further dialyzed against purification water in a dialysis bag (retained molecular weight: 500 Da) for 7 days. Finally, the clear, light, brown GQDs aqueous was concentrated using a rotary evaporation (RE-52AA) and dried in a Freeze Drying Machine (Lab-1-80) to obtain solid GQDs.
5：Data Analysis Methods
The optical properties of the as-prepared GQD and the GQD-Tb solutions using the ultraviolet-visible (UV-Vis) absorption and the fluorescence emissions of the GQD-Tb solutions.
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