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O: Fachverband Oberflächenphysik

O 31: Heterogeneous Catalysis: Theory

O 31.4: Vortrag

Dienstag, 8. März 2016, 11:15–11:30, S053

Embedding of Vanadium Atoms into the Anatase TiO2(101) Surface — Stig Koust¹, Logi Arnarson^1,2, Paul Georg Moses², Igor Beinik¹, Zheshen Li¹, Jeppe Vang Lauritsen¹, and •Stefan Wendt¹ — ¹Interdisciplinary Nanoscience Center (iNANO) and Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark — ²Haldor Topsøe Research Labs, DK-2800 Lyngby, Denmark

Selective catalytic reduction (SCR) catalysis is widely used to reduce NOx into N2 and H2O in flue and exhaust gasses, often using ammonia (NH3) as H source. SCR reactions are best catalyzed by anatase TiO2-supported submonolayer VOx-catalysts that are promoted with W and/or Mo. Here we present atomically resolved STM images of sub-monolayer V on anatase TiO2(101). Following V deposition at 100 K, the surface was covered with small isolated V clusters that were distributed homogeneously on the terraces. Our STM studies revealed an embedding of V into the near-surface region upon warming the sample to room temperature. A significant decrease in the density of V clusters was observed and new features in the STM images appeared, which we assign to monomeric V at regular Ti surface sites. Thus, surface Ti atoms are substituted by V atoms. Additional XPS characterization revealed the oxidation state of V being 2+ directly after deposition at 100 K, indicating a preferred binding between V clusters and surface O atoms. Characteristic changes were observed in the V 2p region after warming the sample to room temperature, corroborating our STM data.