Synthesis of fluorescent carbon quantum dots from Manihot esculenta waste peels for nonlinear optical and biological applications

Abstract

The synthesis of carbon quantum dots using cassava (Manihot esculenta) waste peels by simple hydrothermal method. Carbon quantum dots were studied using PXRD, and HRTEM analysis, signifying an amorphous graphite carbon structure. The carbon quantum dots have two absorption peaks in the UV–vis spectrum, around 272 and 304 nm which lead to the π–π* and n–π* transitions. The produced CQDs exhibit excitation dependent fluorescence characteristics, with a fluorescence quantum yield of 4.664% at an excitation wavelength of 330 nm. The CQDs revealed a white light emitting diode with the Commission Internationale d'Eclairage (CIE) coordinates (0.35, 0.35). The nonlinear optical absorption 0.294×10−4 (cm/W), nonlinear refractive index 1.8138×10−8 (cm2/W), and third-order NLO susceptibility 5.5 × 10−6 (esu) were calculated using Z-Scan analysis. The synthesized CQDs were utilized for their antibacterial activity used S. aureus (23 mm), B. cereus (33 mm), E. coli (43 mm), and P. aeruginosa (30 mm) as harmful microbes. Our results suggest that Manihot esculenta waste peels CQDs have potential for application in NLO devices, optical switching, and pharmaceuticals.

Keywords

• Carbon quantum dots
• Fluorescence
• Light emitting diode
• Nonlinear optical
• Antibacterial activity