Facile synthesis of high-performance sulfur quantum dots via an effective ethylenediamine-assisted acceleration strategy for fluorescent sensing

The present quest for sulfur quantum dots (SQDs) has been to circumvent the inefficient and laborious process involved in previous synthesis strategies. Here, intensely blue-emitting SQDs with a quantum yield up to 14.22 % are prepared by an effective ethylenediamine-assisted acceleration strategy with sublimated sulfur to SQDs conversion on the order of 6 h. The forming of SQDs includes the cleavage of bulk sublimated sulfur powders into small particles of sulfur-nitrogen compounds in the presence of ethylenediamine, which are oxidized to SQDs. The critical finding of this work is that sublimated sulfur can be rapidly converted from zero-valent sulfur to polysulfide by simple heating in the effect of ethylenediamine that dramatically boosts preparation efficiency. Significantly, the combination of SQDs and MnO2 nanosheets achieve fluorescence/scattered light ratiometric sensing of ascorbic acid with a limit of detection of 11.31 nM. This work provides a facile and rapid method for the fabrication of SQDs that could even enable SQDs to be applied in more expansive fields than carbon QDs and silicon QDs in the future.