Periodic Reporting for period 1 - NATFOX (Novel nano thin film oxygen electrodes for solid oxide cells)
Periodo di rendicontazione: 2023-03-20 al 2025-03-19
The project, NATFOX, focuses on studying the fundamental properties of materials to support the development of advanced, efficient oxygen electrodes for reversible solid oxide cells (SOCs), contributing to a greener economy. A key outcome is the development of a novel technique—isotopic exchange Raman spectroscopy (IERS)—which offers the research community new tools for investigating oxygen electrode materials. This technique not only provides valuable insights for designing new materials but also builds a knowledge base that supports both current and future industrial applications. The IERS technique has been significantly improved to overcome the intrinsic limitations of Raman spectroscopy. It now applies to bulk samples, enabling deeper structural and chemical analysis, and has been integrated with other techniques to offer a more complete understanding of oxygen mass transport dynamics in oxygen ionic conducting materials under various atmospheric conditions.
The novel IERS method, based upon the Raman frequency shift due to the changes in isotope concentration, has been demonstrated as a powerful technique to study the oxygen diffusion and surface exchange kinetics in situ with unprecedented time resolution. However, the existence of at least one active oxygen vibrational Raman mode is the prerequisite to apply IERS to characterize oxygen transport of a given material. This confines its application to a limited range of materials, with its applicability determined on a case-by-case basis.
To address this limitation, we demonstrate that by an innovative method, it is possible to apply this novel universal IERS technique to study the oxygen surface exchange dynamics independent of the vibrational properties of the functional materials. A multilayer thin film configuration has been designed with the main components of the functional layer, the probe layer, and the blocking layer. It is anticipated that this universal IERS method will quickly establish itself as a standardised in situ methodology for studying ion transport dynamics, benefiting research on ionic conducting and mixed materials for a broad range of solid-state electrochemical energy devices.
In addition, the IERS technique has been extended to bulk samples. Our results provide significant insights for understanding the structure, defect chemistry, composition, and oxygen mass transport dynamics in the doped ceria single phase and dual phase composites, where the oxygen surface exchange and bulk diffusion kinetics are in good agreement with the secondary ion mass spectrometry (SIMS) results. This study will be a starting point for more sophisticated and quantitative analysis on broader solid state ionic materials systems, particularly combined with more advanced data analysis techniques involved with machine learning.
Furthermore the IERS was carried out to understand the environmental effects. A combination of different in situ kinetic measurements such as Raman, electrical conductivity relaxation and time-resolved X-ray diffraction was applied to achieve holistic information on structure, mass and charge transport.
To address this limitation, we demonstrate that by an innovative method, it is possible to apply this novel universal IERS technique to study the oxygen surface exchange dynamics independent of the vibrational properties of the functional materials. A multilayer thin film configuration has been designed with the main components of the functional layer, the probe layer, and the blocking layer. It is anticipated that this universal IERS method will quickly establish itself as a standardised in situ methodology for studying ion transport dynamics, benefiting research on ionic conducting and mixed materials for a broad range of solid-state electrochemical energy devices.
In addition, the IERS technique has been extended to bulk samples. Our results provide significant insights for understanding the structure, defect chemistry, composition, and oxygen mass transport dynamics in the doped ceria single phase and dual phase composites, where the oxygen surface exchange and bulk diffusion kinetics are in good agreement with the secondary ion mass spectrometry (SIMS) results. This study will be a starting point for more sophisticated and quantitative analysis on broader solid state ionic materials systems, particularly combined with more advanced data analysis techniques involved with machine learning.
Furthermore the IERS was carried out to understand the environmental effects. A combination of different in situ kinetic measurements such as Raman, electrical conductivity relaxation and time-resolved X-ray diffraction was applied to achieve holistic information on structure, mass and charge transport.
The impact enabled by this project will be significant and wide ranging due to the versatile applications of the technique. The IERS method has demonstrated as an alternative approach to the conventional isotopic exchange depth profiling (IEDP)-SIMS method to study the oxygen mass transport dynamics in nano thin films. Compared to the conventional method, it is more efficient, non-destructive and provides additional structural information and time resolution. Additionally, the IERS method can be further upgraded to various isotopic elements in solid state materials enabling mechanism studies on ion transport dynamics. This results in wider applications of the materials in energy section, as many energy devices such as solid state batteries, solid oxide cells (SOCs), proton conducting fuel cells are all based upon solid state ionics where ionic mass transport plays a key role.
Economically and societally, the low-cost IERS is more easily accessible compared to IEDP-SIMS method, therefore screening of appropriate oxygen electrode materials for the applications of SOCs will be significantly accelerated. The impact from innovative materials with direct applications in reversible micro-SOCs can be indirectly achieved by the fast material screening of IERS. Additionally, the materials studied in this work are used in SOC devices which are fully conformant with the EU’s goal of decarbonisation.
This preliminary initiative will continuously stimulate innovation on advanced characterisation on ionic mass transport studies: the results from this project have successfully demonstrated that this IERS technique can be further extended to a universal situation regardless of the intrinsic limitations for the measured materials and its dimensional scale.
Economically and societally, the low-cost IERS is more easily accessible compared to IEDP-SIMS method, therefore screening of appropriate oxygen electrode materials for the applications of SOCs will be significantly accelerated. The impact from innovative materials with direct applications in reversible micro-SOCs can be indirectly achieved by the fast material screening of IERS. Additionally, the materials studied in this work are used in SOC devices which are fully conformant with the EU’s goal of decarbonisation.
This preliminary initiative will continuously stimulate innovation on advanced characterisation on ionic mass transport studies: the results from this project have successfully demonstrated that this IERS technique can be further extended to a universal situation regardless of the intrinsic limitations for the measured materials and its dimensional scale.