User research at BESSY II: Formation of a 2D meta-stable oxide in reactive environments
Illustration of a CuxOy structure formed on a AgCu alloy in oxidizing environments described in this work. (c) ACS Applied Materials & Interfaces. © (2020) ACS Publishing
The chemical behaviour of solid material surfaces is an important physical characteristic for applications of catalysis, chemical sensors, fuel cells and electrodes. A research team from the Max Planck Institute for Chemical Energy Conversion has now described an important phenomenon that can occur when metal alloys are exposed to reactive environments at the synchrotron source BESSY II.
In a recent work published in ACS Applied Materials & Interfaces, a researchers’ team led by Dr. Mark Greiner (Surface Structure Analysis, Department of Heterogeneous Reactions) demonstrates an important phenomenon that can occur when metal alloys face reactive environments. They can form meta-stable 2D oxides on their surfaces. Such oxides exhibit chemical and electronic properties that are different from their bulk counterparts. Due to their meta-stability, their existence is also difficult to predict.
This publication displays the results of a thorough investigation of one such oxide, confirming previous theoretical predictions of its existence, and helps to advance the understanding of the complexity of solid surfaces in reactive environments. The investigations were performed using in-situ photon electron spectroscopy at the ISISS beamline and the UE49-PGM beamline at BESSY II.
This investigation was a collaborative research effort between the Max Planck Institute for Chemical Energy Conversion, the Max-Planck-Institut für Eisenforschung, the Fritz Haber Institute of the Max Planck Society, the Helmholtz Zentrum Berlin and the Italian National Research Council Institute of Materials (CNR-IOM).
- Metallic nanocatalysts: what really happens during catalysisUsing a combination of spectromicroscopy at BESSY II and microscopic analyses at DESY's NanoLab, a team has gained new insights into the chemical behaviour of nanocatalysts during catalysis. The nanoparticles consisted of a platinum core with a rhodium shell. This configuration allows a better understanding of structural changes in, for example, rhodium-platinum catalysts for emission control. The results show that under typical catalytic conditions, some of the rhodium in the shell can diffuse into the interior of the nanoparticles. However, most of it remains on the surface and oxidises. This process is strongly dependent on the surface orientation of the nanoparticle facets.
- KlarText Prize for Hanna TrzesniowskiThe chemist has been awarded the prestigious KlarText Prize for Science Communication by the Klaus Tschira Foundation.
- Shedding light on insulators: how light pulses unfreeze electronsMetal oxides are abundant in nature and central to technologies such as photocatalysis and photovoltaics. Yet, many suffer from poor electrical conduction, caused by strong repulsion between electrons in neighboring metal atoms. Researchers at HZB and partner institutions have shown that light pulses can temporarily weaken these repulsive forces, lowering the energy required for electrons mobility, inducing a metal-like behavior. This discovery offers a new way to manipulate material properties with light, with high potential to more efficient light-based devices.