Rapid Synthesis of Sulfur Nanodots by One-Step Hydrothermal Reaction for Luminescence-Based Applications

As a single-element nanomaterial, sulfur nanodots are emerging as a kind of heavy-metal-free nanomaterials which are believed to excel over traditional undesirable compound semiconductor nanocrystals in practical applications. Attaining their potential shall rest on the facile fabrication of high quality samples. Yet, so far the reported fabrication techniques for fluorescent sulfur nanodots have been time-consuming and cost-ineffective. Instead, we employed a strategy of hydrothermal reaction to synthesize sulfur nanodots, which reduces the synthesis time remarkably from generally required 125 h to 4 h. As-synthesized sulfur nanodots (without any post-treatment) manifest good monodispersity and a reasonable photoluminescence quantum yield up to 4.02%. The fission-aggregation mechanism has been proposed to account for the reaction dynamics in the formation of sulfur nanodots. Optical spectroscopic analysis indicates the existence of tail states in the electronic structures of sulfur nanodots, and the photoluminescence properties are governed by both the core and surface states of the sulfur nanodots, which may provide usable hints for manipulating and harnessing the luminescence properties. Besides the insight into both the synthesis and emission mechanism of luminescent sulfur nanodots, our findings pave the way to the bio-related expedite exploitation of these materials.