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

Abstract

Oxygen activity and surface stability are two key parameters in the search for advanced materials for intermediate temperature solid oxide electrochemical cells, as overall device performance depends critically on them. In particular in situ and operando characterisation techniques have accelerated the understanding of degradation processes and the identification of active sites, motivating the design and synthesis of improved, nanoengineered materials. In this short topical review we report on the latest developments of various sophisticated in situ and operando characterization techniques, including transmission and scanning electron microscopy, surface-enhanced Raman spectroscopy, electrochemical impedance spectroscopy, x-ray diffraction and synchrotron-based x-ray photoelectron spectroscopy and x-ray absorption spectroscopy, among others. We focus on their use in three emerging topics, namely: (i) the analysis of general electrochemical reactions and the surface defect chemistry of electrode materials; (ii) the evolution of electrode surfaces achieved by nanoparticle exsolution for enhanced oxygen activity and (iii) the study of surface degradation caused by Sr segregation, leading to reduced durability. For each of these topics we highlight the most remarkable examples recently published. We anticipate that ongoing improvements in the characterisation techniques and especially a complementary use of them by multimodal approaches will lead to improved knowledge of operando processes, hence allowing a significant advancement in cell performance in the near future.

Nanostructure Engineering and Modulation of (Oxy)Nitrides for Application in Visible‐Light‐Driven Water Splitting

“…4) (Oxy)nitride‐based heterostructures remain a hot spot for future investigations, and additional challenges such as forming intimate interfaces at the atomic level, constructing efficient built‐in electric fields, and exploring innovative synthetic methods still need to be overcome. 5) Theoretical simulations, [ 89 ] time‐ and space‐resolved spectroscopy, [ 5 ] and in situ/operando characterization methods [ 90 ] should be widely employed in the field of (oxy)nitride‐based semiconductors to investigate structure‐related characteristics and guide their syntheses for the modulation of the structures.…”

Silica: ubiquitous poison of metal oxide interfaces

“…70,71 A large number of operando methods have been developed to examine SOFC/SMOX. [72][73][74] In the field of SMOX based gas sensing, operando x-ray adsorption spectroscopy is used to study the oxidations state and structural parameters of surface additives on the interaction with the surrounding atmosphere. 75,76 Operando vibration spectroscopy, both Raman and diffuse Please do not adjust margins Please do not adjust margins reflectance infrared Fourier transform (DRIFT) are widely used to look at the surface chemistry of SMOX based gas sensor and have recently been used to examine fuel cells.…”

Tailored nano-columnar La2NiO4 cathodes for improved electrode performance

“…1,2 Consequently, signicant efforts have been undertaken to improve and conserve the surface exchange activity of various electrode materials at low temperatures, 3 with a strong focus on perovskite and perovskite related oxides, 4 accompanied by the development and advance of new experimental techniques to access fundamental knowledge of elementary processes. 5,6 As described by Yang et al, high cathode activity is a combination of (i) intrinsic activity, dened by physicochemical properties including charge carrier densities and their mobilities, defect formation enthalpies, etc. and (ii) apparent activity, e.g.…”