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Regensburg 2016 – scientific programme

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O: Fachverband Oberflächenphysik

O 31: Heterogeneous Catalysis: Theory

O 31.4: Talk

Tuesday, March 8, 2016, 11:15–11:30, S053

Embedding of Vanadium Atoms into the Anatase TiO2(101) SurfaceStig Koust1, Logi Arnarson1,2, Paul Georg Moses2, Igor Beinik1, Zheshen Li1, Jeppe Vang Lauritsen1, and •Stefan Wendt11Interdisciplinary 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.

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