In Situ and Surface-Enhanced Raman Spectroscopy Study of Electrode Materials in Solid Oxide Fuel Cells

Abstract

Solid oxide fuel cells (SOFCs) represent next-generation energy sources with high energy conversion efficiencies, low pollutant emissions, good flexibility with a wide variety of fuels, and excellent modularity suitable for distributed power generation. As an electrochemical energy conversion device, the SOFC's performance and reliability depend sensitively on the catalytic activity and stability of electrode materials. To date, however, the development of electrode materials and microstructures is still based largely on trial-and-error methods because of the inadequate understanding of electrode process mechanisms. Therefore, the identification of key descriptors/properties for electrode materials or functional heterogeneous interfaces, especially under in situ/operando conditions, may provide guidance for the design of optimal electrode materials and microstructures. Here, Raman spectroscopy is ideally suited for the probing and mapping of chemical species present on electrode surfaces under operating conditions. And to boost the sensitivity toward electrode surface species, the surfaceenhanced Raman spectroscopy (SERS) technique can be employed, in which thermally robust SERS probes (e.g., Ag@ SiO 2 core-shell nanoparticles) are designed to make in situ/operando analysis possible. This review summarizes recent progresses in the investigation of SOFC electrode materials through Raman spectroscopic techniques, including topics of early stage carbon deposition (coking), coking-resistant anode modification, sulfur poisoning, and cathode degradation. In addition, future perspectives for utilizing the in situ/operando SERS for investigations of other electrochemical surfaces and interfaces are also discussed.

Synergetic Interaction of Additive Dual Nanocatalysts to Accelerate Oxygen Reduction Reaction in Fuel Cell Cathodes

“…In comparison with the emerging protonic ceramic fuel cells, − the solid oxide fuel cells (SOFCs) − are these days commercially available with applications including stationary power supply and advanced hybrid fuel cell and engine systems that have the potential of achieving ultrahigh efficiency of greater than 70%. , Nevertheless, there is an urgent need for further improvement of the SOFC performance in terms of power density and long-term stability to increase their market competencies. The typical power density of a yttria-stabilized zirconia (YSZ)-based commercial SOFC is currently reported to be in the range of ∼0.2–0.8 W/cm 2 depending on the cell configuration (either electrolyte-supported or anode-supported), cathode materials, and the cell operating conditions. − Regardless of the intense research effort during the past decade, the high activation energy for oxygen reduction reaction (ORR) in the cathode is still the major cause hindering the power density of the state-of-the-art SOFCs.…”

In situ and operando characterisation techniques for solid oxide electrochemical cells: recent advances

“…Raman spectroscopy constitutes a very simple and effective tool which has been extensively used in situ and ex situ to probe surface species such as oxygen, sulfur, hydrocarbons and water [6] and to probe structural changes upon oxidation or reduction, resulting in changes in the vibration modes of the electrode materials' structure. For further details on this technique the reader is addressed to the following comprehensive reviews [3], [6], [18]. Being one of the limitations of Raman spectroscopy its lack of sensitivity to many surface species, enhanced Raman spectroscopy (SERS) has aroused as a promising solution.…”

A Mini Review on the Application of Proton-Conducting Solid Oxide Cells for CO2 Conversion

“…It is critical to determine the reaction intermediates to reveal the reaction path. To reveal the reaction mechanism, in situ technologies, such as synchrotron-based near ambient XPS/X-ray adsorption spectroscopy, ,− in situ Raman, in situ scanning probe microscopy, , in situ XRD, and in situ FTIR, are critical for investigating the materials’ properties during operation and determining the reaction intermediate. Combining experimental results with multiscale calculation approaches is also required to reveal the reaction kinetics and provide critical information for the rational design of novel materials.…”