One-pot synthesis of carbon dots from neem resin and the selective detection of Fe(ii) ions and photocatalytic degradation of toxic dyes

Abstract

The sustainable utilization of biomass has attracted great interest worldwide. A remarkably brand-new, environmentally friendly technique is created to prepare fluorescent carbon dots (CDs). This study used neem resin as a hydrothermal precursor to synthesize neem resin-derived CDs (NR-CDs). Electron microscopy- and spectroscopy-related techniques were used to characterize these NR-CDs. These NR-CDs exhibited a fluorescence peak at 420 nm with a quantum yield of 21%, allowing them for sensitive detection of Fe²⁺ ions with a corresponding limit of detection as low as 14 nM. The as-synthesised NR-CD fluorescent probe was applied to determine Fe²⁺ in real samples of drinking, river, and tap water, highlighting its practical applications. Additionally, these NR-CDs were utilized as a photocatalyst to degrade Rhodamine B, Fast Green, and Naphthol Yellow dyes in industrial wastewater in the presence of NaBH₄ as a surface defect modifier. Under exposure to visible light, NR-CDs were highly efficient for degrading Rhodamine B, Fast Green, and Naphthol Yellow, with degradation rates of 93.13%, 93.01%, and 91.29%, respectively. The proposed mechanism outlines a multi-step process for photocatalytic degradation of organic dyes by using the NR-CDs; further this study demonstrates the multifaceted utility of NR-RCDs in diverse applications, from ion detection in environmental samples to bio-imaging and efficient catalytic degradation of various dyes.