Energy Conversion Catalysis by Operando Spectroscopy /BElChem-PGM

The scientific aim at the BElChem-PGM instrument is to study the electronic surface/near surface structure of functional materials in the presence of a reactive environment. This includes both gas/solid interfaces (e.g. heterogeneous catalysis) and liquid/solid interfaces (e.g. catalytic water splitting).

The instrument is located at the BElChem-PGM beamline which covers the soft X-ray energy range from approximately 100 eV to 2000 eV with a plane grating monochromator. Its source is a planar undulator with a period length of 49.4 mm (U49-2) and minimum gap of 16 mm. The optical elements and layout of the beamline have been optimized to deliver a high photon flux over a broad energy range, in particular at energies above 800 eV, with moderate spectral resolution. This helps to facilitate in-situ and operando experiments that are conducted at elevated gas pressures or in liquids.

Selected Applications:

• X-ray photoelectron spectroscopy (XPS) under high vacuum (p=10^(-8) mbar) and near ambient pressure conditions (maximum 20 mbar, typically 1 mbar)
• X-ray aborption spectroscopy (XAS) at pressure up to 20 mbar with NAP-HE-XPS endstation
• log-in methodology applying the beamline chopper to modulate the incoming X-ray induced signal

Methods

NEXAFS, XRF, Time-resolved absorption, XPD, NAP-XPS, XPS, XPD, Time-resolved PES, Mass Spectrometry

Remote access

not possible

Obviously, the understanding of the interaction of a catalyst surface with the reactants plays a key role in a detailed description of catalytic processes. X-ray photoelectron spectroscopy (XPS) is a well-established powerful tool to study in detail the outermost surface of solids, but it was traditionally restricted to high vacuum and low pressure conditions. However, recently a methodology based on a differentially pumped electrostatic lens system has gained much interest and opened the possibility to study catalytic processes in more diverse environments.

The Berlin Joint Lab for Electrochemical Interfaces (BElChem) is located at the BESSY II synchrotron in Berlin, Germany, and co-run by the Fritz-Haber-Institut (FHI), the Max Planck Institute for Chemical Energy Conversion (MPI-CEC) and the Helmholtz-Zentrum Berlin. BElChem focuses on providing a molecular-level description of (photo)electrochemical interfaces that are of high relevance for solar fuel production and renewable energy storage.

The BElChem facility consists of two instruments in two separate hutches and an additional sample preparation/chemical lab. BElChem-PGM (plane grating monochromator) covers the soft X-ray energy range, whereas BElChem-DCM (a dipole magnet sourced beamline) with a double crystal monochromator (DCM) covers the tender X-ray energy range.