Strain engineering of selective chemical adsorption on monolayer MoS2

Abstract

Nanomaterials are prone to influence by chemical adsorption because of their large surface to volume ratios. This enables sensitive detection of adsorbed chemical species which, in turn, can tune the properties of the host material. Recent studies discovered that single and multi-layer molybdenum disulfide (MoS₂) films are ultra-sensitive to several important environmental molecules. Here we report new findings from ab inito calculations that reveal substantially enhanced adsorption of NO and NH₃ on strained monolayer MoS₂ with significant impact on the properties of the adsorbates and the MoS₂ layer. The magnetic moment of adsorbed NO can be tuned between 0 and 1 μ_B; strain also induces an electronic phase transition between the half-metal and the metal. Adsorption of NH₃ weakens the MoS₂ layer considerably, which explains the large discrepancy between the experimentally measured strength and breaking strain of MoS₂ films and previous theoretical predictions. On the other hand, adsorption of NO₂, CO, and CO₂ is insensitive to the strain conditions in the MoS₂ layer. This contrasting behavior allows sensitive strain engineering of selective chemical adsorption on MoS₂ with effective tuning of mechanical, electronic, and magnetic properties. These results suggest new design strategies for constructing MoS₂-based ultrahigh-sensitivity nanoscale sensors and electromechanical devices.