Molybdenum Disulfide Quantum Dots Prepared by Bipolar-Electrode Electrochemical Scissoring

A convenient bipolar-electrode (BPE) electrochemical method was engineered to produce molybdenum disulfide (MoS₂) quantum dots (QDs) using pure phosphate buffer (PBS) as the electrolyte and the MoS₂ powder as the precursor. Meanwhile, the corresponding by-product precipitate was studied, in which MoS₂ nanosheets were observed. The BPE design would not be restricted by the shape and size of the MoS₂ precursor. It could lead to the defect generation and 2H → 1T phase variation of the MoS₂, resulting in the formation of nanosheets and finally the QDs. The as-prepared MoS₂ QDs exhibited high photoluminescence (PL) quantum yield of 13.9% and average lateral size of 4.4 ± 0.2 nm, respectively. Their excellent PL property, low cytotoxicity, and good aqueous dispersion offer promising applicability in PL staining and cell imaging. Meanwhile, the as-obtained byproduct containing the nanosheets could be used as an effective electromagnetic wave (EMW) absorber. The minimum reflection loss (RL) value was -54.13 dB at the thickness of 3.3 mm. The corresponding bandwidth with efficient attenuation (<-10 dB) was up to 7.04 GHz (8.8-15.84 GHz). The as-obtained EMW performance was far superior over most previously reported MoS₂-based nanomaterials.