Parametric study and characterization of nitrogen-doped carbon quantum dots synthesized via hydrothermal method

Abd Razak, Jeefferie and Zulkarnain, Wan Putri Najihah and Munawar, Rose Farahiyan and Mohamad, Noraiham and Othman, Intan Sharhida and Abdul Latif, Nurul Ayunni and Puspitasari, Poppy (2025) Parametric study and characterization of nitrogen-doped carbon quantum dots synthesized via hydrothermal method. Malaysian Journal on Composites Science and Manufacturing, 16 (1). pp. 111-124. ISSN 2716-6945

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Abstract

Carbon quantum dots (CQDs) are zero-dimensional nanomaterials known for their chemical stability, water dispersibility, low cytotoxicity, small size, biocompatibility, and photoluminescence. This study reports the synthesis of nitrogen-doped carbon quantum dots (N-CQDs) using urea and citric acid derived from calamansi lime via a simplified hydrothermal method. A 2³full factorial Design of Experiments (DOE) was employed to optimize synthesis parameters, comprising temperature, reaction time, and precursor ratio, with optimal conditions identified as 140 °C, 2 hours, and a 1:1 precursor ratio. The resulting N-CQDs exhibited strong photoluminescence, excellent colloidal stability, and particle sizes ranging from 5 to 10 nm. Tauc plot analysis indicated bandgap energies up to 5.81 eV, influenced by particle size and quantum confinement. UV-Vis and FTIR spectroscopy confirmed the absorption behavior and the presence of nitrogen and oxygen functional groups, respectively, while photoluminescence measurements showed intense emission. FESEM, TEM, and EDX analyses revealed uniform spherical morphology and confirmed successful nitrogen doping. Overall, the tunable surface chemistry and optical properties of N-CQDs make them promising for bioimaging, sensing, and optoelectronics applications. At the same time, the sustainable, cost-effective hydrothermal synthesis method supports scalable production for use as functional fillers in nanocomposites.

Item Type:	Article
Uncontrolled Keywords:	N-CQDs, Hydrothermal synthesis, Photoluminescence, Green chemistry, Tauc plots, Functional filler
Divisions:	Faculty Of Industrial And Manufacturing Technology And Engineering
Depositing User:	Sabariah Ismail
Date Deposited:	11 Aug 2026 04:12
Last Modified:	11 Aug 2026 04:12
URI:	http://eprints.utem.edu.my/id/eprint/30215
Statistic Details:	View Download Statistic

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