| AVS 60th International Symposium and Exhibition | |
| Atom Probe Tomography Focus Topic | Wednesday Sessions |
| Session AP+AS+MI+NS+SS-WeA |
| Session: | APT and FIM Analysis of Catalysts and Nanoscale Materials |
| Presenter: | T. Li, Oxford University, UK |
| Authors: | T. Li, Oxford University, UK P.A.J. Bagot, Oxford University, UK S.C.E. Tsang, Oxford University, UK G.D.W. Smith, Oxford University, UK |
| Correspondent: | Click to Email |
Bimetallic heterogeneous catalysts have proven remarkably successful in catalysing a wide range of important processes, in fuel-cells, exhaust emission control and in hydrocarbon processing. However, the effects of the operating environment on the surface composition, structure and stability of the noble metal catalysts are poorly understood at the atomic-scale. This knowledge will be required to produce the improved catalysts needed for future energy- and materials-efficient technologies.
Atom probe tomography offers a unique method for studying these materials, offering atomic-scale chemical identities of the catalyst surfaces and chemisorbed species. We have used APT to show a rich variety of behaviour in Pt-based alloys, investigating the effects of high temperature/pressure oxidation. These reveal pronounced surface segregation behaviour, strongly dependent on the treatment conditions, crystallographic plane and alloy composition. Furthermore, while subsequent reduction treatments remove formed oxides, the marked changes to the metallic surface compositions remain. Such results suggest using sequential oxidation and reduction treatments as an alternative synthesis method for designing and preparing nano catalysts with controlled surface compositions.
Another aspect of our work focuses on the investigation of the use of APT for characterizing catalyst nanoparticles either in colloidal dispersions or on the carbon supports. It is very challenging to fully characterize these complex 3D architectures by conventional electron microscope technique. In this work, we have for the first time demonstrated the use of APT for the analysis and characterization of such materials in atomic detail. Alongside a description of the preparations, we will also present a range of results from these catalysts materials, highlighting the correction between catalytic efficiency and the atomic-scale chemical/structural information uniquely provided by APT.