Speaker
Description
In the CatLab project, thin closed metal films (< 10nm) are deposited on a defined support material. In this way, the support material can influence the properties of the metal catalyst in a designed manner despite not being directly exposed to the reaction gas mixture. Such a sample configuration reduces the complexity of the catalyst – support perimeter region and simplifies the characterization of the catalyst and its catalytic activity. Deliberate tuning of energetic and geometrical properties of the catalyst paves the way for a dense population of active centers on the surface that is required for a catalytically active thin layer metal catalyst. Physical vapor deposition (PVD) of Pd- and Pt-based thin-film catalysts was performed at Helmholtz-Zentrum Berlin (HZB) using a custom-built sputtering facility embedded in the infrastructure of the Energy Materials In Situ Lab (EMIL), providing direct access to synchrotron-based (in situ) analyses (XPS, NEXAFS) jointly carried out with the Inorganic Chemistry Department (AC) from FHI. Various complementary analyses (XRD, (S)TEM, Thermal Methods, Calorimetry, IR measurements) were conducted by AC at IRIS in Adlershof. A wide range of targets is available to deposit metals including Pd, Pt, Cu, Au or Ir. For the catalyst support, sputtering, e-beam evaporation and chemical vapor deposition (esp. PECVD) allows for fabrication of dense and temperature stable materials like SiO$_{2}$, Si$_{3}$N$_{4}$, SiC, ZnO, Al$_{2}$O$_{3}$ or CeO$_{2}$. Coatings can be performed on substrates up to 8-inch or 100x100 mm². Smaller scale model functional thin films (<=1 cm ) are prepared at the Interface Science Department (ISC) of FHI by PVD under UHV conditions followed by ex and in-situ characterization (XPS and STM) in gas mixtures. Structural and chemical characterization is achieved with a high-resolution LEEM/PEEM system combining microscopy, spectroscopy (XPS at BESSY). Exploration and optimization of ideal conditions in this large factor space of deposition parameters is pursued with adaptive design of experiments in collaboration with the Theory Department (TH) of the FHI. The films are catalytically tested in dedicated reactors in the Catlab laboratories of AC (IRIS, Adlershof). One being a Berty reactor, which was successfully adapted for the use with flat surfaces. Additional reactor concepts are being developed in cooperation with external partners. In the Enerchem project (BASF, FHI, HZB) unique reactors for hydrogen generating reactions are being developed to allow the kinetic characterization of thin films. With Reacnostics, a reactor was adapted allowing spatial resolution of the reaction profile between two films.s built showing almost ideal CSTR behavior, allowing kinetic catalytic measurements on thin films. In another cooperation between HZB and Reacnostics, an existing profile reactor was adapted allowing a spatial resolution of the reaction profile between two films. Additionally, a design for a stagnation flow reactor was proposed allowing in situ spectroscopy on thin films under well defined, relevant conditions.
| Abstract Number (department-wise) | AC 6.4 |
|---|---|
| Department | AC (Schlögl) |
