Decomposition pathways of NO on carbide and oxycarbide-modified W(111) surfaces

Abstract The decomposition of NO has been studied on clean W(1 1 1), carbide-modified W(1 1 1), and oxycarbide-modified W(1 1 1) surfaces. The decomposition pathways are investigated using a combination of temperature programmed desorption, Auger electron spectroscopy, high-resolution electron energy loss spectroscopy, and soft X-ray photoelectron spectroscopy. All these surfaces exhibit high activity toward the decomposition of NO, and the only N-containing products are N 2 and N 2 O. Furthermore, all three surfaces preferentially produce N 2 over N 2 O from the decomposition of NO. Oxygen atoms, produced from the decomposition of NO, react with carbide surfaces to produce gas-phase CO at high temperatures. In addition, our results demonstrate that cycles of alternate NO/hydrocarbon treatments can regenerate the carbide overlayer on W(1 1 1), and the regenerated C/W(1 1 1) surface remains active in the decomposition of NO.