Operando Absorption and Emission Spectroscopy at EMIL

In context of the growing need for a more sustainable energy sector, significant efforts have been devoted to the quest for more efficient electrocatalyst materials for energy conversion and storage devices such as water electrolyzers, fuel cells and batteries. In-situ x-ray spectroscopic studies of promising energy materials in conditions close to real operation are of crucial importance for understanding of the performance-limiting mechanisms occurring at the electrochemical interfaces.

The OAESE instrument - an infrastructure that allows x-ray absorption spectroscopic (NEXAFS) studies of energy materials under operating conditions - is part of the Energy Materials in-situ laboratory EMIL, which is a unique infrastructure designed to allow for in-system, in-situ, and operando X-ray analysis of an unprecedented range of materials and devices for energy conversion and storage. The interchange of samples between the instrument and all tools allows novel multipart experiments to be performed.

The EMIL beamline has two branches – soft (80 eV – 1800 eV) and hard (1800 eV – 10 keV) x-rays – which converge at the OAESE instrument.

Selected Applications:

• Investigation of electrocatalyst materials by means of operando x-ray absorption spectroscopy (operando NEXAFS) at the soft and tender x-ray regime
• Study of transition metal (TM)-based electrocatalysts under operating conditions mainly by TM L-edge soft NEXAFS and K-edge hard NEXAFS
• Fundamental understanding of the electronic structure and degradation mechanisms of lithium-ion battery electrodes during operation
• Operando NEXAFS following the in-situ electrodeposition of catalytical active materials

Schematics of the OÆSE endstation in EMIL@BESSY II. An integrating photon detector at 45°collects the fluorescence photons emitted by the sample

Methods

RIXS, NEXAFS

Remote access

not possible

3-electrode flow-through cell designed for operando spectroscopic experiments with reliable electrochemistry

A thin x-ray transparent membrane separates the UHV environment from the examined material allowing for photon-in/photon-out spectroscopic techniques while working simultaneously as electrode

The instrument setup is based on a three-electrode electrochemical liquid flow-cell attached to an ultra-high vacuum chamber (UHV) dedicated for in-situ/operando studies. To isolate the cell environment containing liquid electrolyte from the UHV of the analysis chamber, a very thin (about 100 nm) x-ray transparent window is mounted in the flow-cell. The modular design of the electrochemical cell easily allows for project-specific modifications besides the standard use with liquid electrolyte. The system is installed at the open port interaction point SISSY-II of the 2-color undulator-based EMIL beamline covering a probing energy range from the extreme ultraviolet (~80 eV) up to the hard x-ray regime (~10 keV). Photon-in/photon-out NEXAFS spectra of all relevant elements can be collected at appropriately fast timescales (i.e., several minutes) enabling measurements during normal operation of a myriad of energy materials.