Effects of Coal Rank and High Organic Sulfur on the Structure and Optical Properties of Coal‐based Graphene Quantum Dots
Effects of Coal Rank and High Organic Sulfur on the Structure and Optical Properties of Coal‐based Graphene Quantum Dots
复制标题
DOI：
10.1111/1755-6724.13600
复制
发表时间：
2018-06
期刊：
影响因子：
--
通讯作者：
Yuegang Tang;Xu Huan;Chunyuan Lan;Miaoxin Xu
中科院分区：
文献类型：
--
作者：
Yuegang Tang;Xu Huan;Chunyuan Lan;Miaoxin Xu
采用六种不同煤阶的一步化学合成方法成功制备了煤基石墨烯量子点（GQDs），其中选择了两种超高有机硫（SHOS）煤作为天然S掺杂碳源制备了S掺杂GQDs。采用高分辨率透射电子显微镜（HRTEM）、X射线衍射（XRD）、傅里叶变换红外光谱（FTIR）、X射线光电子能谱（XPS）、紫外-可见（UV - Vis）吸收光谱和荧光发射光谱分析了煤的性质对煤基GQDs的影响。结果表明，所有的煤样品都可以制备出在紫外光下发出蓝绿和蓝色荧光的GQDs。无烟煤基GQDs具有无缺陷的六方晶体结构，尺寸最大，片层中碳环排列密集；高阶烟煤基GQDs尺寸相对减小，其六方晶体结构仅依稀可见；低阶烟煤基GQDs最小，具有稀疏的晶格条纹和可见的内部缺陷。随着原煤变质作用的增加，产率降低，荧光量子产率（QY）先增大后减小。此外，使用高阶煤（高阶烟煤）制备的GQDs表面即使经过强氧化也能保持丰富的硫含量，这有效地调节了带隙，提高了荧光QY。因此，含SHOS的高阶烟煤可作为天然S掺杂碳源制备S掺杂GQDs，扩大了低品位煤的清洁利用。
Coal‐based graphene quantum dots (GQDs) were successfully produced via a one‐step chemical synthesis from six different coal ranks, from which two superhigh organic sulfur (SHOS) coals were selected as natural S‐doped carbon sources for the preparation of S‐doped GQDs. The effects of coal properties on coal‐based GQDs were analyzed by means of high‐resolution transmission electron microscopy (HRTEM), X‐ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, X‐ray photoelectron spectroscopy (XPS), ultraviolet‐visible (UV‐Vis) absorption spectroscopy, and fluorescence emission spectra. It was shown that all coal samples can be used to prepare GQDs, which emit blue‐green and blue fluorescence under ultraviolet light. Anthracite‐based GQDs have a hexagonal crystal structure without defects, the largest size, and densely arranged carbon rings in their lamellae; the high‐rank bituminous coal‐based GQDs are relatively reduced in size, with their hexagonal crystal structure being only faintly visible; the low‐rank bituminous coal‐based GQDs are the smallest, with sparse lattice fringes and visible internal defects. As the metamorphism of raw coals increases, the yield decreases and the fluorescence quantum yield (QY) initially increases and then decreases. Additionally, the surface of GQDs that were prepared using high‐rank SHOS coal (high‐rank bituminous coal) preserves rich sulfur content even after strong oxidation, which effectively adjusts the bandgap and improves the fluorescence QY. Thus, high‐rank bituminous coal with SHOS content can be used as a natural S‐doped carbon source to prepare S‐doped GQDs, extending the clean utilization of low‐grade coal.