Abstract:
Recently, carbon nanodots (CNDs), the zero-dimensional carbon nanomaterials,
have attracted immense research interest. Besides inherent traits like
biocompatibility, eco-friendliness, electron mobility, and water-soluble nature, CNDs, as
a green material with inherent luminescence, have grabbed a lot of attention and have
opened up applications in more real-world contexts. In the present study, we project
methionine-derived N, S co-doped CNDs as an efficient candidate for white-light-emitting
diode (WLED) applications and dual-mode multianalyte sensing, based on their covetable
fluorescence. Here, a scalable, dry white-light-emitting solid material is achieved from the
aqueous dispersion of CNDs through freeze-drying process, without encountering the usual
hurdles that are met with in solid-state CND systems, such as aggregation-caused
quenching (ACQ) in luminescence, incomplete dryness, and low yield. The present system
stands distinct, as warm white light is achieved by simply integrating the white light
emitting single-component derived CND powder with near ultraviolet LED chips (370
nm) without ACQ resistors or additional phosphors. WLEDs with a low correlated color temperature of 3762 K and a moderately
high color rendering index, which are suitable for interior lighting, are achieved. Along with the optoelectronic application, the
system is potent enough to respond to the presence of two biologically significant species, folic acid and Fe3+ ions, through a dualmode
operation, viz, fluorescence turn-on and turn-off strategies, respectively. Excellent selectivity from a galaxy of 34 analytes is
noted for the system, with attractive detection limits of 0.709 and 14.08 μM for folic acid and ferric ion, in the respective order. A
detailed investigation of the mechanisms proves the inner filter effect (IFE) and Forster resonance energy transfer-mediated
fluorescence enhancement and IFE-mediated quenching effect, operating here.
