Importance of the catalytic effect of the substrate in the functionality of lubricant additives: the case of molybdenum dithiocarbamates

Molybdenum dithiocarbamates (MoDTCs) are lubricant additives very efficient in reducing the friction of steel and they employed a number industrial applications. The functionality these is ruled by chemical interactions occurring at buried sliding interface, which key importance for improvement lubrication performance. Yet, tribochemical processes difficult to monitor real time. Ab initio molecular dynamics simulations ideal tool shed light into such complicated reactivity. In this work we perform ab simulations, both static tribological conditions, understand effect surface oxidation on reactivity MoDTC find that when surfaces covered oxygen, first dissociative steps significantly hindered. Our preliminary tests oxidized discs support results. Bare metallic necessary stable adsorption additives, their quick decomposition, formation durable MoS$_2$ tribolayer. This demonstrates catalytic role substrate confirms full capability computational protocol pursuit materials compounds more friction.