Surface Engineering of MoS2 via Laser-Induced Exfoliation in Protic Solvents.

With excellent performance in the hydrogen evolution reaction (HER), molybdenum disulfide (MoS2 ) is considered a promising nonprecious candidate to substitute Pt-based catalysts. Herein, pulsed laser irradiation in liquid is used to realize one-step exfoliation of bulk 2H-MoS2 to ultrastable few-layer MoS2 nanosheets. Such prepared MoS2 nanosheets are rich in S vacancies and metallic 1T phase, which significantly contribute to the boosted catalytic HER activity. Protic solvents play a pivotal role in the production of S vacancies and 2H-to-1T phase transition under laser irradiation. MoS2 exfoliated in an optimal solvent of formic acid exhibits outstanding HER activity with an overpotential of 180 mV at 10 mA cm-2 and Tafel slope of 54 mV dec-1 .