Laser Light Induced Transformation of Molybdenum Disulphide-Based Nanoplatelet Arrays

One-pot hydrothermal synthesis of MoS₂ nanoplatelet arrays on various substrates is perhaps the most promising approach to fabricate efficient electrocatalysts for hydrogen evolution reaction. However, the main challenges in this synthesis remain the purity and crystallinity of MoS₂. In this study, we show for the first time that irradiation of amorphous, defect-rich MoS₂ nanoplatelets with a green nanosecond laser at a proper irradiation dose, ca ≤0.35 J cm^-2, can significantly improve the crystallinity and purity of MoS₂ nanoplatelets. The effect was confirmed by Raman spectroscopy investigations demonstrating a surprising intensity increase of the A¹_g and modes after the laser irradiation. Further increase of irradiation energy, however, resulted in the photocorrosion and destruction of MoS₂ nanoplatelets. The variation of A¹_g and Raman mode intensities ratio depending on the green light irradiation dose was also presented and is discussed below.