Controlling Selectivity in the Chlorine Evolution Reaction over RuO 2 ‐Based Catalysts

In the industrially important Chlor‐Alkali process, the chlorine evolution reaction (CER) over a ruthenium dioxide (RuO 2 ) catalyst competes with the oxygen evolution reaction (OER). This selectivity issue is elucidated on the microscopic level with the single‐crystalline model electrode RuO 2 (110) by employing density functional theory (DFT) calculations in combination with the concept of volcano plots. We demonstrate that one monolayer of TiO 2 (110) supported on RuO 2 (110) enhances the selectivity towards the CER by several orders of magnitudes, while preserving the high activity for the CER. This win‐win situation is attributed to the different slopes of the volcano curves for the CER and OER.