Economizing on Precious Metals in Three‐Way Catalysts: Thermally Stable and Highly Active Single‐Atom Rhodium on Ceria for NO Abatement under Dry and Industrially Relevant Conditions**

Abstract

We show for the first time that atomically dispersed Rh cations on ceria, prepared by a high-temperature atom-trapping synthesis, are the active species for the (CO+NO) reaction. This provides a direct link with the organometallic homogeneous Rh^I complexes capable of catalyzing the dry (CO+NO) reaction. The thermally stable Rh cations in 0.1 wt % Rh₁ /CeO₂ achieve full NO conversion with a turn-over-frequency (TOF) of around 330 h^-1 per Rh atom at 120 °C. Under dry conditions, the main product above 100 °C is N₂ with N₂ O being the minor product. The presence of water promotes low-temperature activity of 0.1 wt % Rh₁ /CeO₂ . In the wet stream, ammonia and nitrogen are the main products above 120 °C. The uniformity of Rh ions on the support, allows us to detect the intermediates of (CO+NO) reaction via IR measurements on Rh cations on zeolite and ceria. We also show that NH₃ formation correlates with the water gas shift (WGS) activity of the material and detect the formation of Rh hydride species spectroscopically.