Bodík Michal, Annušová Adriana, Hagara Jakub, Mičušík Matej, Omastová Mária, Kotlár Mário, Chlpík Juraj, Cirák Július, Švajdlenková Helena, Anguš Michal, Roldán Alicia Marín, Veis Pavel, Jergel Matej, Majkova Eva, Šiffalovič Peter
Institute of Physics, Slovak Academy of Sciences, Dubravska cesta 9, 845 11 Bratislava, Slovakia.
Polymer Institute, Slovak Academy of Sciences, Dubravska cesta 9, 845 41 Bratislava, Slovakia.
Phys Chem Chem Phys. 2019 Jun 21;21(23):12396-12405. doi: 10.1039/c9cp01951k. Epub 2019 May 29.
It is generally accepted that liquid-phase exfoliation (LPE) enables large-scale production of few-layer MoS flakes. In our work, we studied in detail few-layer MoS oxidation in the course of standard LPE in a water/ethanol solution. We demonstrate that an increase of the initial MoS concentration above a certain threshold triggers a pronounced oxidation and the exfoliation process starts to produce MoO nanoparticles. A subsequent decrease of the water pH along with an increased content of SO suggests an oxidation scenario of few-layer MoS oxidation towards MoO nanoparticles. Moreover, the lowered pH leads to agglomeration and sedimentation of the few-layer MoS flakes, which significantly lowers their production yield. We employed a large number of physico-chemical techniques to study the MoS-to-MoO transformation and found a threshold value of 10 mg ml of the initial MoS concentration to trigger this transformation.
一般认为，液相剥离法（LPE）能够大规模生产少层MoS薄片。在我们的工作中，我们详细研究了在水/乙醇溶液中进行标准LPE过程中少层MoS的氧化情况。我们证明，初始MoS浓度增加到一定阈值以上会引发明显的氧化，并且剥离过程开始产生MoO纳米颗粒。随后水的pH值下降以及SO含量增加，表明少层MoS向MoO纳米颗粒氧化的情况。此外，pH值降低会导致少层MoS薄片团聚和沉淀，这显著降低了它们的产量。我们采用了大量物理化学技术来研究MoS向MoO的转变，发现初始MoS浓度的阈值为10 mg/ml时会引发这种转变。
