Selenium-doped WS2 for improved humid-air lubricity via weakened interfacial hydrogen bonding

• • DFT calculations reveal that water forms O–H···Se hydrogen bonds with WSe2 at bond lengths of 3.02–3.25 Å, which are significantly longer (weaker) than O–H···S bonds with WS2 (2.80–2.98 Å), leading to a 35% lower interlayer sliding energy barrier for WSe2 under humid conditions. • • Selenium doping of WS2 (W–S–Se coating) achieves an 18% reduction in coefficient of friction and a 78% decrease in wear rate at 40% relative humidity compared to pristine WS2, demonstrating a viable strategy to mitigate moisture-induced degradation. • • The improved tribological performance is attributed to weakened interfacial hydrogen bonding, which reduces the energy penalty for interlayer shear, as confirmed by DFT and sliding friction experiments. • • The W–S–Se coating forms a reoriented, crystalline transfer layer with insignificant oxidation, indicating that the lubricious mechanism is preserved even in humid air, offering a robust solution for solid lubrication in ambient environments.