Sub-hour pulsed laser ablation synthesis of dual-emissive carbon nanoparticles from lemon leaves

Plant leaf carbon nanoparticles (C NPs) are growing in green nanotechnology for their affordability, sustainability, and safety. Here we show that a 30-minute pulsed-laser ablation in distilled water converted intact lemon leaves into C NPs averaging 26 nm in diameter. The study demonstrated for the first time dual emissions from intact lemon-leaf matrices under nanosecond laser ablation. The morphological and optical properties of the resulting C NPs were characterized using transmission electron microscopy, UV–Vis spectrophotometry, Fourier transform infrared spectrometry (FTIR), and photoluminescence analyses. These C NPs absorbed strongly at 283 and 314 nm, corresponding to the π–π* transitions of C = C and the n–π* transition of C = O bonds, respectively and displayed dual photoluminescence at 336 nm (blue) and 460 nm (cyan-green) arising from core and oxygenated surface states, respectively. FTIR analysis confirmed the presence of surface traps on the surface of the C NPs. The reagent-free, sub-hour process yielded dual-band emitters suitable for various applications such as ratiometric sensing or optoelectronics.