碳源组成对碳微球形貌及光谱学特性的影响

Chemical Compositions of Carbon Sources Affected on Surface Morphology and Spectral Properties of the Synthetic Carbon Microspheres

碳微球作为一种新型碳材料,具有较高的比表面积和电导率,且表面富含羟基、羧基、羰基等活性基团,这使碳微球在吸附、催化剂载体、电极电池等领域具有广泛的应用前景。该研究通过水热法,分别以生物质水解液(葡萄藤、紫茎泽兰)、糖(木糖、葡萄糖、蔗糖)为碳源制备碳微球。使用场发射扫描电子显微镜(field emission scanning electron microscope,FE-SEM)、衰减全反射红外光谱(attenuated total reflection fourier transform infrared spectroscopy,ATR-FTIR)和光电子能谱(X-ray photoelectron spectroscopy,XPS)对不同碳源碳微球的表观形貌及光谱学性质进行表征。并对红外光谱指纹特征区域(2000~800 cm^-1)的数据进行自动基线校正、自动平滑、归一化等处理,对处理后主要官能团的光谱数据进行主成分分析(principal component analysis,PCA),以探究不同碳源碳微球之间光谱学特性的差异。研究结果表明:碳微球得率、粒径分布与碳源种类相关。糖源碳微球粒径分布规律为蔗糖>葡萄糖>木糖,粒径分布在0.3~1.6μm之间;生物质源碳微球为紫茎泽兰>葡萄藤,粒径分布在0.1~0.6μm。红外光谱显示,生物质和糖源在碳化过程中均发生了脱水、脱羧、芳构化以及缩合反应,不同碳源制备的碳微球均含有芳香环结构;此外,碳微球表面存在O—H和CHO等含氧官能团。在主成分分析中,第一主成分(PC1)和第二主成分(PC2)代表了83.1%的指纹区变量信息,能够反映原始光谱的主要信息。在主成分得分图中,不同碳源碳微球的分布相对独立,说明碳微球在化学组成上有明显的差异性。因此,光谱学特性上的差异可作为鉴别和分类不同碳源制备碳微球的主要依据,研究结果为进一步探讨和不同碳源碳微球的光谱学特性提供理论依据和研究基础。

Carbon microspheres,as a new type of carbon material,have a high specific surface area and high electrical conductivity.There are a lot of reactive groups such as hydroxyl carbonyl and carboxyl groups on the surface of the microsphere,which makes it suitable for a wide range of application prospects on adsorbent materials,catalyst carriers,electrode battery materials,et cetera.By this research,the hydrothermal carbon microspheres were synthesized from different carbon sources including the natural biomass(Vitis vinifera and Eupatorium adenophorum)and saccharides(xylose,glucose and sucrose).To explore the effect of the composition of the carbon sources on the morphology and chemical structure,the properties of different carbon microspheres were characterized by Field Emission Scanning Electron Microscope(FE-SEM),Attenuated Total Reflection Fourier Transform Infrared Spectrometer(ATR-FTIR)and X-ray Photoelectron Spectroscopy(XPS).The infrared spectra of 2000~800 cm^-1 in the fingerprint characteristic region were selected.The original infrared spectra data were pretreated by automatic baseline correction,automatic smoothing,ordinate normalization and analyzed by principal component analysis(PCA)for probing the differences in spectral properties between different carbon microspheres.The results showed that the morphology and particle size distribution of carbon microspheres were closely related to the raw material.The carbon microsphere prepared by saccharides,which diameter was approximately in the 0.3~1.6μm range,sucrose>glucose>xylose.And the particle size distribution of biomass carbon microsphere was 0.1~0.6μm,Eupatorium adenophorum>Vitis vinifera.In the carbonation reaction,biomass and saccharides had a series of dehydration,decarboxylation,aromatization and condensation reaction.In terms of the chemical structure,no matter the complexity of carbon sources,the carbon microspheres all had aromatic ring structure and outer surface contained a high concentration of reactive oxygen groups,such as O—H,CHO.The PCA results showed that two main components represented 83.1%fingerprint region variable information,which could reflect the main information of the original spectrum.In the principal component scores figure,the distribution of different carbon microspheres was relatively independent,there were obvious differences in the chemical composition of the synthetic carbon microspheres derived from different carbon sources.Therefore,the difference in the intensity of absorption peak could provide an effective reference for the identification of carbon microsphere from different carbon sources.The results could provide a theoretical basis for further exploration of the spectral properties of carbon microspheres prepared by different carbon sources under hydrothermal conditions.