Phase-Reversed MoS₂ Nanosheets Prepared through Femtosecond Laser Exfoliation and Chemical Doping

Metallic 1T MoS 2 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 MoS 2 nanosheets through light exfoliation and chemical doping by femtosecond laser ablation of bulk 2H-phase MoS 2 crystals in a Fe ion solution. Femtosecond laser induces the light exfoliation of MoS 2 with the breakage of chemical bonds and increased chemical activity of MoS 2, which is conducive to the chemical adsorption and doping of Fe atoms on MoS 2 and hence to the reversion of the original 2H phase to a 1T phase, finally obtaining 1T-phase MoS 2 nanosheets. The prepared MoS 2 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 MoS 2 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 MoS 2 nanosheets, thus proving their huge potential for catalysis and energy applications.