Comparative investigation of the vibrational properties of bulk 2<i>H</i>–MoS₂ and its exfoliated nanosheets under high pressure

Abstract

In this paper, we present a comparative study of the vibrational properties of bulk MoS 2 and its exfoliated nanosheets under high pressure by resonant Raman spectroscopy. The X‐ray photoelectron spectroscopy measurements demonstrate that the nanosheets made by chemical lithium insertion method are mainly consisted of metallic 1 T phase. The wavenumbers of the and A lg Raman modes for the few layer nanosheets show a linear relationship with pressure which is different from the multilayer MoS 2 . This phenomenon is due to the differences in their electronic band structure. The systematic research about the 2LA (M) in bulk 2 H –MoS 2 suggests that the high pressure behaviour of this double resonance Raman mode arises from the pressure‐induced metallization and band gap closure. These difference vibrational properties for few and multilayer MoS 2 can be applied for exploring pressure‐modulated advanced devices. Copyright © 2017 John Wiley &amp; Sons, Ltd.