Rosales Stephania, Zapata Karol, Medina Oscar E, Rojano Benjamin A, Taborda Esteban A, Cortés Farid B, Pérez-Cadenas Agustín F, Bailón-García E, Carrasco-Marín Francisco, Franco Camilo A
Grupo de Investigación en Fenómenos de Superficie-Michael Polanyi, Departamento de Procesos y Energía, Facultad de Minas, Universidad Nacional de Colombia, Sede Medellín Medellín 050034 Colombia
Grupo de Investigación Química de los Productos Naturales y los Alimentos, Escuela de Química, Facultad de Ciencias, Universidad Nacional de Colombia, Sede Medellín Medellín-Antioquia 050034 Colombia.
Nanoscale Adv. 2025 Jul 14. doi: 10.1039/d5na00554j.
This study investigates the influence of the chemical nature of nitrogen sources on the optical properties of Carbon Quantum Dots (CQDs) and evaluates their suitability for various industrial applications through a series of stability tests. Four nitrogen sources, -diethanolamine, diethylamine, ethylenediamine, and 1,2-phenylenediamine- were used to synthesize surface-active CQDs a one-step microwave-assisted carbonization method. All CQDs exhibited a negative surface charge, ranging from -24.1 to -26.2 mV, indicating excellent colloidal stability at the working pH of 7. Nitrogen was successfully incorporated in all cases; however, CQDs synthesized with ethylenediamine and phenylenediamine showed significantly higher nitrogen contents. This increased incorporation was directly correlated with higher fluorescence quantum yields (QYs), reaching 20.44% with ethylenediamine and 22.61% with phenylenediamine, representing an improvement of up to 220% compared to those synthesized with other nitrogen sources. In addition to the nitrogen content, the carbon structure also influences the QY. Higher proportions of C[double bond, length as m-dash]C bonds contribute to more extensive sp-conjugated domains, promoting electron delocalization and enhancing both electronic transitions and fluorescence efficiency. However, physical properties, such as particle size and thermal stability, remained unaffected by the choice of the nitrogen precursor. The CQDs demonstrated excellent thermal stability, ionic strength resistance, and long-term fluorescence retention, maintaining up to 90% of their initial fluorescence intensity under various storage conditions, making them suitable for use in harsh environments. However, an extremely acidic pH had the most detrimental effect, causing fluorescence intensity losses of up to 80% in CQD-phenylenediamine and CQD-diethylamine. These findings highlight the important role of nitrogen in enhancing the optoelectronic properties of the CQDs. Appropriate selection of the nitrogen source can significantly improve the fluorescence performance and optimize the response for practical applications.
本研究调查了氮源的化学性质对碳量子点（CQDs）光学性质的影响，并通过一系列稳定性测试评估了它们在各种工业应用中的适用性。使用四种氮源——二乙醇胺、二乙胺、乙二胺和1,2-苯二胺——通过一步微波辅助碳化法合成了表面活性CQDs。所有CQDs均表现出负表面电荷，范围为-24.1至-26.2 mV，表明在工作pH值为7时具有优异的胶体稳定性。在所有情况下氮均成功掺入；然而，用乙二胺和苯二胺合成的CQDs显示出明显更高的氮含量。这种增加的掺入与更高的荧光量子产率（QYs）直接相关，乙二胺合成的CQDs的QYs达到20.44%，苯二胺合成的CQDs的QYs达到22.61%，与用其他氮源合成的相比提高了高达220%。除了氮含量外，碳结构也影响QY。较高比例的C=C键有助于形成更广泛的sp共轭域，促进电子离域并增强电子跃迁和荧光效率。然而，诸如粒径和热稳定性等物理性质不受氮前驱体选择的影响。CQDs表现出优异的热稳定性、抗离子强度性和长期荧光保留能力，在各种储存条件下可保持高达其初始荧光强度的90%，使其适用于恶劣环境。然而，极端酸性pH值的影响最为不利，导致CQD-苯二胺和CQD-二乙胺的荧光强度损失高达80%。这些发现突出了氮在增强CQDs光电性质方面的重要作用。适当选择氮源可显著改善荧光性能并优化实际应用中的响应。
