RESUMEN
Photoluminescent carbon dots (PL CDs) have drawn tremendous attention from researchers owing to their admirable properties and wide range of applications. Herein, highly PL nitrogen and sulfur doped carbon dots (N,S-CDs) were synthesized through a facile, green and rapid one-step microwave assisted method using goat hooves, a bio-waste and a green precursor. The structural and photophysical properties of as obtained N,S-CDs were thoroughly investigated. From the investigation, it is revealed that the N,S-CDs possess a spherical morphology with an average particle size of about 2 nm, highly amorphous nature, high functionality, negative zeta potential (-32 mV), good water-solubility, excitation dependant PL, high PL quantum yield (23.8%), nanosecond lifetime (τ avg = 3.38 ns) and excellent storage stability for 180 days without any agglomeration. In addition, the N,S-CDs exhibit high PL stability under diverse pH conditions, wide ionic strength and resistance towards photobleaching, which are very important properties for practical applications. The N,S-CDs selectively sense Au3+ ions and also reduce the Au3+ ions to metallic gold. Hence, the N,S-CDs were successfully applied as a potential candidate for sensing of Au3+ and simultaneous extraction of metallic gold in aqueous media without any further reducing agents. It is a significant green way for the recovery of gold in aqueous media.
RESUMEN
Synthesizing nano carbon from its bulk precursors is of recent research interest. In this report, luminescent carbon nanoparticles (CNPs) with tunable particle size and surface functionality are fabricated from lignite using ethylenediamine as the reactive solvent and surface passivating agent via different experimental methods. From the steady-state and time-resolved photophysical studies of these differently sized CNPs, it is unveiled that the energy of the excitons generated after photoexcitation is quantum confined, and it influences the observed photophysical behaviour significantly only when the particle size is less than 10 nm. A larger size of the CNPs and less surface functionalization lead to aggregation, and quenching of the fluorescence. But by dispersing smaller size CNPs in sodium sulfate matrix exhibits fluorescence in the solid state with an absolute fluorescence quantum yield of â¼34%. The prospective application of this hybrid material in sensing and removal of moisture in the atmosphere is illustrated.