Remarkable luminescent carbon quantum dots: green synthesis from orange juice using microplasma-liquid method

Abstract

Green carbon quantum dots (CQDs) were fabricated through microplasma-liquid interactions, involving the treatment of an orange juice solution at atmospheric pressure and room temperature. Morphological analyses of the CQDs revealed a spherical shape with an average size of approximately 2.5 nm. The emission peak at a wavelength of 440 nm was observed for the blue emissive CQDs, with an excitation wavelength of 350 nm. The CQDs exhibited excellent luminescence activity, with emission dependent on the excitation wavelength, shifting towards longer wavelengths. The Raman spectrum of the CQDs displayed two peaks at 1425.3 and 1625.4 cm−1, representing predominantly disorder and graphitic bands. These green-synthesized CQDs possess tunable luminescence and biocompatibility, making them promising candidates for potential applications in biolabelling, antibacterial agents and optoelectronics.