Fritz-Haber-Institut der Max-Planck-Gesellschaft  

Inorganic Chemistry – Electrochemistry Group
  

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Electrochemistry Group:
Sébastien Cap
 
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Electrochemistry and charge transport at interfaces
 
Research area

The electrochemistry research group, hosted by the Department of Inorganic Chemistry of the FHI, is composed of a multidisciplinary team of scientists performing experimental and fundamental research on a vast portfolio of solid state materials. The principal aim of the electrochemistry group is to study the fundamental physicochemical processes that are involved in energy storage systems for storing intermittent renewable energy. More specifically, we are systematically varying the structural (topography, allotropes) and electronic properties (doping, surface chemical functionalization) of solid state materials, followed by a comprehensive characterization of their consequent functional properties using a variety of complementary in situ or in operando analytical techniques. This robust methodology aims to derive fundamental relationships between the material’s structural and electronic peculiarities and several performance metrics (e.g. selectivity and stability) to ultimately establish a basis for further and more rational material optimization.

Scientific scope

The electrochemistry research group, performs fundamental and applied experimental research framed within three research areas, namely energy storage, water electrolysis, and charge transport characterization across interfaces.
Silicon based anode investigations for lithium ion batteries

The development of electrochemical devices with high energy density accompanied by long cycling life is essential to store energy produced by intermittent and renewable energy sources. Contemporary efforts aim at substituting the remarkably stable graphite anode in lithium ion batteries by other solid state materials, such as silicon. This substitution has a significant impact on the electrochemical dynamics and stability of the electrode, and consequently on the energy accumulator. It is our principal aim to better understand the fundamental relationship between structural and electronic factors at the electrode-electrolyte interface and their influence on the mechanically and electrochemically irreversible mechanisms, i.e. the electrode stability and dynamics.
Water electrolysis

Accompanying the development of energy storage devices, electrocatalysis will play definitive role in energy storage technologies and energy conversion systems of the near future, such as water electrolysis. While the desired product of water splitting is hydrogen, which can be used as combustion gas or as a reactant to produce synthetic fuels, the limiting catalytic process is related to the oxygen evolution reaction (OER). The objective of this research is to develop complementary in situ methods to improve our mechanistic understanding of the OER and of the electrode stability and dynamics under working conditions. As example, we are devoting efforts to develop in situ near-ambient-pressure XPS and grazing angle XRD as analytical tools for the in situ studies of novel iridium based electrocatalysts for the OER.
Charge carrier characterisation using microwave based techniques

At its most fundamental level, the transformation and storage of chemical energy, as well as the product formation in heterogeneous catalysis, is accompanied by a local displacement of charge carriers, often across an interface. Our group has developed a set of tools, based on the Microwave Cavity Perturbation Technique (MCPT) and Microwave Hall Effect (MHE) to characterize in situ and contactless the dielectric properties of materials including thermally activated catalysts, for example VPP or MoVTeNbOx. More specifically, these powerful instrumental techniques enable us to characterize a catalyst’s conductivity, its charge carrier concentration and mobility. We have recently demonstrate the applicability of semiconductor physics and gas sensor theory to gain valuable mechanistic understanding of vanadium based catalysts using the MCPT technique complemented by near-ambient-pressure XPS and NEXAFS.
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