Effect of a humid environment on the surface structure ofRuO2(110)

Combining density-functional theory and thermodynamics we compute the phase diagram of surface structures of rutile ${\mathrm{RuO}}_{2}(110)$ in equilibrium with water vapor in the complete range of experimentally accessible gas phase conditions. Through the formation of hydroxyl or waterlike groups, already lowest concentrations of hydrogen in the gas phase are sufficient to stabilize an oxygen-rich polar oxide termination even at very low oxygen pressure.