Biosynthesis of the Narrowband Deep-Red Emissive Carbon Nanodots from Eggshells

Safely recycling high-performance fluorescent materials from waste is an appealing route to reduce environmental pollution. This work presents one facile approach to massively producing high-performance carbon nanodots (CNDs) from discarded cooked eggshells. The obtained CND solution exhibits two excitation-independent deep-red emission peaks at 632 and 700 nm with a high photoluminescence quantum yield of 19.98% and a narrow full width at half-maximum (FWHM) of 16.2 nm. The deep-red emission of the CNDs originates from the porphyrin-like structure in the CNDs, which are formed in the eggshells and further carbonized by cooking. In addition, the deep red emission and unprecedented narrow FWHM of the CNDs deliver promising applications in bioimaging as an imaging agent. The recycled deep-red emissive CNDs pave a new strategy to design nanomaterials from biomass and provide a novel green pathway to recycle high-performance fluorescent nanomaterials sustainably.