Bio-Genic Synthesis of Nitrogen-Doped Carbon Nanodots (NDCNDs) Using Aristolochia bractealata for MO Catalytic Activity and Security Ink

This study presents a straightforward hydrothermal method for synthesizing fluorescent nitrogen-doped carbon nanodots (NDCNDs). The Aristolochia bractealata (A. bractealata) extract is utilized as a carbon source, while aqueous ammonia serves as a nitrogen source. An analysis of the optical characteristics of synthesized NDCNDs is conducted utilizing UV–visible and fluorescence spectroscopy. The NDCNDs are analyzed for their morphology, functional groups, crystallinity, and elemental composition using advanced analytical techniques such as HR-TEM with EDS, XRD, and FT-IR. The chemically produced nitrogen-doped carbon nanodots emit intense blue fluorescence with a wavelength of 400 nm when excited by light with a wavelength of 320 nm. In addition, the fluorescence of produced NDCNDs also exhibits excitation-dependent emission characteristics. The HR-TEM analysis indicates that the synthesized nitrogen-doped carbon nanodots (NDCNDs) exhibit a sphere shape with a typical diameter of 2.5 nm. The XRD result demonstrates the graphitic characteristics of the synthesized NDCNDs. The EDS and FT-IR analyses provide evidence of nitrogen doping. The resulting non-doped carbon nanodots (NDCNDs) acted as an environmentally friendly catalyst, significantly improving the reducing ability of sodium borohydride (NaBH₄) in the catalytic reduction of methyl orange (MO) dye. Furthermore, the fluorescent characteristics of synthesized NDCNDs in a vibrant blue color were employed as a means of identification in anti-counterfeiting applications.