Phase-Reversed MoS₂Nanosheets Prepared through Femtosecond Laser Exfoliation and Chemical Doping

Metallic 1T MoS2 nanosheets are highly desirable for application in catalysis, energy storage, and energy production due to their high electrical conductivity and abundant active sites. Here, this work presents a new strategy to prepare 1T-phase MoS2 nanosheets through light exfoliation and chemical doping by femtosecond laser ablation of bulk 2H-phase MoS2 crystals in a Fe ion solution. Femtosecond laser induces the light exfoliation of MoS2 with the breakage of chemical bonds and increased chemical activity of MoS2, which is conducive to the chemical adsorption and doping of Fe atoms on MoS2 and hence to the reversion of the original 2H phase to a 1T phase, finally obtaining 1T-phase MoS2 nanosheets. The prepared MoS2 nanosheets have a uniform shape and size, high crystallinity, coexisting 1T and 2H phases, highly active S, and are chemically combined with Fe atoms. Moreover, the prepared phase-reversed MoS2 nanosheets can be applied as electrocatalysts for the electrochemical hydrogen evolution reaction (HER) and exhibit a considerable enhancement of the HER catalytic activity compared with the common 2H-phase and ion-intercalated MoS2 nanosheets, thus proving their huge potential for catalysis and energy applications.