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Journal of Metals, Materials and Minerals

Publication Date

2026

Abstract

This study reports the synthesis of graphene quantum dots (GQDs) via a bottom-up carbonization approach using citric acid as a precursor under various reduced pressure conditions. The carbonization process was carried out at 250℃ in an ethanol medium, with atmospheric pressures ranging from normal to 20 inHg below atmospheric pressure. The effects of pressure reduction on the size and optical properties of GQDs were systematically investigated. Dynamic light scattering (DLS), UV–Vis spectroscopy, and fluorescence spectroscopy revealed that pressure reduction during synthesis decreased GQDs size and induced a blue-shift in both absorption and emission spectra. The optical bandgap of GQDs was tunable by varying the synthesis pressure, and strong blue fluorescence was observed under UV excitation. FT-IR analysis confirmed the formation of functional groups on the GQD surface, while the absence of epoxy-related bands indicated complete carbonization of the precursor. These findings demonstrate that pressure-controlled carbonization offers an effective method for tailoring the structural and photoluminescent properties of GQDs, enabling their application in optoelectronic and sensing devices.

DOI

10.55713/jmmm.v36i1.2412

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