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<p>In this work, we confirmed the presence of Carbon Quantum Dots (CQDs) by optical techniques such as UV-visible and photoluminescence (PL), after filtering the result of carbonization and sulfonation of microcrystalline cellulose (MCC), which are synthesis processes for obtaining these nanomaterials. The high-resolution transmission electron microscopy (HR-TEM) confirmed, not only the size of the particles, but the crystalline pattern of the carbon-based nanoparticles. The HR-TEM also indicates the presence of Graphene Quantum Dots (GQDs), as anisotropic-shaped particles were observed. Fluorescence and absorbance indicate the pH dependence on optical and structural properties, as well as on the production of CQDs and GQDs. The pH may influence the syntheses of CQDs and GQDs and the origin of their fluorescence, due to presence of functional groups such as hydroxyl, carboxyl, carbonyl, epoxy, and sulfoxide at low pH, and in the edge regions of these particles, with sp² hybridization. The Fourier Transform Infrared (FTIR) spectra was also measured, allowing to understand the functional groups present in the samples, and so, understand the groups responsible for the fluorescence.</p>

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Influence of the pH on the Synthesis of Carbon Quantum Dots and Graphene Quantum Dots

  • 期刊论文

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  • 发表日期：

    2026年6月19日

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  • Pedro Holland de Oliveira,
  • Ana Champi

摘要

In this work, we confirmed the presence of Carbon Quantum Dots (CQDs) by optical techniques such as UV-visible and photoluminescence (PL), after filtering the result of carbonization and sulfonation of microcrystalline cellulose (MCC), which are synthesis processes for obtaining these nanomaterials. The high-resolution transmission electron microscopy (HR-TEM) confirmed, not only the size of the particles, but the crystalline pattern of the carbon-based nanoparticles. The HR-TEM also indicates the presence of Graphene Quantum Dots (GQDs), as anisotropic-shaped particles were observed. Fluorescence and absorbance indicate the pH dependence on optical and structural properties, as well as on the production of CQDs and GQDs. The pH may influence the syntheses of CQDs and GQDs and the origin of their fluorescence, due to presence of functional groups such as hydroxyl, carboxyl, carbonyl, epoxy, and sulfoxide at low pH, and in the edge regions of these particles, with sp² hybridization. The Fourier Transform Infrared (FTIR) spectra was also measured, allowing to understand the functional groups present in the samples, and so, understand the groups responsible for the fluorescence.