Unraveling the mechanism to form MoS<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si94.svg" display="inline" id="d1e451"><mml:msub><mml:mrow /><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:math> lubricant layers from MoDTC by ab initio simulations

The morphology of molybdenum disulfide (MoS2) is a crucial aspect to ensure the functionality this remarkable 2D-material both in electronic and tribological applications. Indeed, dithiocarbamates (MoDTCs) can be tribochemically transformed into MoS2, which able reduce friction coefficient metallic moving parts. However, transformation influenced by temperature, sulfur/oxygen ratio, normal shear stresses, making mechanism process particularly challenging explain. Ab initio simulations based on density functional theory (DFT), including quantum mechanics/molecular mechanics (QM/MM) approach, are used here shed light crystallization MoS2 promoted mechanical stresses. Chemistry plays an important role during reorganization units MoSx obtained from MoDTC, because sulfur oxygen atoms tend move outside amorphous layer, surrounding creating structure that crystallize MoS2. Normal load sliding have synergistic effect rearranging crystalline structure, as former helps overcoming energy barriers associated bonds breaking forming, while latter allows misplaced pulled towards sites. A was ab calculations below 1000 K.