Hydrothermal synthesis and ionic sensing properties of graphitic carbon nitride quantum dots

• Published in: Journal of the Taiwan Institute of Chemical Engineers Vol. 150; p. 105031
• Main Authors: Patra, Rashmiranjan, Yang, Po-Chih, Shu, Da-You, Hsieh, Chien-Te
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.2023
• Subjects: Biocompatibility; Fluorescent sensing; Graphitic carbon nitride; Hydrothermal method; Ionic detection; Quantum dots; Fluorescent sensing; Biocompatibility; Hydrothermal method; Ionic detection; Quantum dots; Graphitic carbon nitride
• ISSN: 1876-1070; 1876-1089
• DOI: 10.1016/j.jtice.2023.105031

•C3N4 quantum dots (QDs) are synthesized via hydroxylation and hydrothermal cutting.•The QD suspension shows a maximal fluorescence intensity (420 nm) at 360 nm.•The QD suspension exhibits high sensitivity toward iron ions with ppm-level.•The QD suspension offers satisfactory biocompatibility toward 3T3 cell after 24 h.•We provide a promising approach to engineering highly fluorescent C3N4 QDs. This work adopts an efficient method including thermal calcination, surface hydroxylation, and hydrothermal cutting to synthesize graphitic C3N4 quantum dots (CNQDs) for detecting metal ions in aqueous solutions. Functionalized CNQDs, ranged from 2 to 6 nm in particle size, were of layered crystalline and contain a large amount of surface functionalities such as carbonyl, carboxylic, and amino groups. The CNQD suspension exhibited a maximal fluorescence intensity at 420 nm with high quantum yield of 13.6% under UV irradiation. The CNQD suspension demonstrated superior sensitivity and selectivity toward iron ions with ppm-level detection limit in liquid phase. The Stern-Volmer analysis revealed that CNQD suspension was appropriate for the detection of Fe3+ and Fe2+ ions with LOD of 6.5 and 7.7 ppm, respectively. The fluorescence quenching mechanism of CNQD suspension mainly originates from a strong interaction between the ions and the surface functionalities followed by the photoinduced energy transfer effect, thus inducing the fluorescence extraction. Moreover, the CNQD suspension also offers a satisfactory biocompatibility toward 3T3 cell after 24 h. Accordingly, the robust design of CNQDs developed in this work paves the way for developing highly sensitive and selective probes for detecting target species in aqueous solutions. [Display omitted]