Due to the quantum confinement effect of graphene quantum dots (GQDs), the fluorescence properties of the GQDs can be adjusted by changing the size of the GQDs. We can obtain better fluorescence properties of the GQDs by varying the preparation conditions. GQDs were prepared by the pyrolysis method. To obtain GQDs with excellent fluorescence properties, the effect of different pyrolysis times and pH values on the properties of GQDs were studied. Fourier infrared spectroscopy, x-ray diffraction, transmission electron microscope, and fluorescence spectroscopy (PL) were used to characterize the morphology, structure, and fluorescence properties of GQDs. The experimental results show that with the increase of pyrolysis time, the carbonization of citric acid intensifies, the size of GQDs increases, the fluorescence peak of GQDs broadens, and the dependence of fluorescence emission increased gradually. Fluorescence property changes with the pyrolysis time, the fluorescence property is optimal with the pyrolysis time of 30 min, and the suitable pyrolysis time will cause the citric acid sufficient reaction to produce the maximum yield of GQDs. Besides, GQDs fluorescence properties are also affected by the acid-base environment. The fluorescence of GQDs solution has the strongest in an alkaline environment and quenched in an acidic environment.

中文翻译：

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不同热解制备条件对石墨烯量子点荧光性能的影响

由于石墨烯量子点 (GQD) 的量子限制效应，可以通过改变 GQD 的大小来调整 GQD 的荧光特性。我们可以通过改变制备条件来获得 GQD 更好的荧光特性。GQDs 是通过热解法制备的。为了获得具有优异荧光性能的GQDs，研究了不同热解时间和pH值对GQDs性能的影响。傅里叶红外光谱、X 射线衍射、透射电子显微镜和荧光光谱 (PL) 被用来表征 GQD 的形态、结构和荧光特性。实验结果表明，随着热解时间的增加，柠檬酸的碳化加剧，GQDs的尺寸增大，GQDs的荧光峰变宽，并且荧光发射的依赖性逐渐​​增加。荧光性质随热解时间而变化，热解时间为30 min时荧光性能最佳，合适的热解时间会使柠檬酸充分反应，产生最大的GQDs。此外，GQDs 的荧光特性也受酸碱环境的影响。GQDs溶液的荧光在碱性环境中最强，在酸性环境中猝灭。GQDs 的荧光特性也受酸碱环境的影响。GQDs溶液的荧光在碱性环境中最强，在酸性环境中猝灭。GQDs 的荧光特性也受酸碱环境的影响。GQDs溶液的荧光在碱性环境中最强，在酸性环境中猝灭。