Facile synthesis of sulfur quantum dots with red light emission: Implications for electrochemiluminescence analysis...

Sulfur quantum dots (SQDs) have been reported as a potential candidate due to their low toxicity and high luminescent performance. Here, SQDs with red light fluorescence (FL) emission were synthesized by a one-step hydrothermal method using Na₂CO₃ as an etching agent, using sublimed sulfur powder as a sulfur source, and using bovine serum albumin (BSA) as a stabilizer. The choice of etching agent (NaOH or Na₂CO₃) realized the tuning of SQDs' FL emission with blue and red light. The synthesized SQDs showed good FL stability and high FL efficiency, with a quantum yield of 1.03 % in an aqueous solution at 575 nm. In addition, stable and efficient electrochemiluminescence (ECL) emission was achieved by employing SQDs as ECL emitters with K₂S₂O₈ as the co-reactant. The resorcinol (RS) can enhance the ECL intensity of the SQDs-K₂S₂O₈ system, and the ECL intensity had a good linear relationship with the concentration of RS in a range from 2.5 nM to 25 nM with a detection limit of 0.61 nM. This work provides an emerging red-light luminescent SQDs, which would open up a way for the development of new types of luminophor in FL or ECL analysis. It also provides convenience for bio-labeling of live cells, in vivo imaging and provide new materials for photoelectric devices.