Here, we report a facile and efficient approach for the large-scale synthesis of highly fluorescent sulfur quantum dots (SQDs) from inexpensive elemental sulfur under a pure oxygen (O₂) atmosphere. The important finding of this work is that the polysulfide (S_x²⁻) ions could be oxidized to zero-valent sulfur (S[0]) by O₂, which is the accelerator of the reaction. The SQDs prepared by this method possess nearly monodisperse size (1.5–4 nm), high fluorescence quantum yield (21.5%), tunable emission, and stable fluorescence against pH change, ionic strength variation and long-term storage. Moreover, the reaction yield of SQDs reached as high as 5.08% based on the content of S element in SQDs, which is much higher than other reported approaches (generally <1%). The prepared SQDs could be easily processed for widespread applications thanks to their low toxicity and superior dispersibility both in water and common organic solvents. These high-quality SQDs may find applications similar to or beyond those of carbon QDs and silicon QDs.

中文翻译：

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氧气加速可扩展的高荧光硫量子点的合成

在这里，我们报告了一种简便有效的方法，可在纯氧（O ₂）气氛下从廉价的元素硫大规模合成高荧光硫量子点（SQD）。这项工作的重要发现是，多硫化物（S _x ^2-）可以被O ₂氧化成零价硫（S [0]）。，它是反应的促进剂。通过这种方法制备的SQD具有近乎单分散的尺寸（1.5–4 nm），高荧光量子产率（21.5％），可调发射以及对pH值变化，离子强度变化和长期存储稳定的荧光。此外，基于SQD中S元素的含量，SQD的反应收率高达5.08％，远高于其他报道的方法（通常<1％）。所制备的SQD毒性低，在水和普通有机溶剂中的分散性强，因此可以轻松地进行广泛应用。这些高质量的SQD可能会发现与碳QD和硅QD相似或超出的应用。