Operando high-temperature near-ambient pressure X-ray photoelectron spectroscopy and impedance spectroscopy study of Ni−Ce0.9Gd0.1O2−δ solid oxide fuel cell anode. (21st September 2020)

• Record Type: Journal Article
• Authors: Kooser, Kuno; Käämbre, Tanel; Vestli, Mihkel; Joost, Urmas; Urpelainen, Samuli; Kook, Mati; Bournel, Fabrice; Gallet, Jean-Jacques; Lust, Enn; Kukk, Edwin; Nurk, Gunnar
• Is Part Of: International journal of hydrogen energy. Volume 45:Number 46(2020)
• Page Start: 25286
• Page End: 25298
• Publication Date: 2020-09-21
• Subjects: Solid oxide fuel cell -- Ni-GDC -- Surface chemistry -- Operando -- NAP-XPS -- EIS; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2020.06.228
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: In this study we present the results of operando high temperature near-ambient-pressure x-ray photoelectron spectroscopy (HT-NAP-XPS) measurements of a pulsed laser deposited thin film N i − C e 0.9 G d 0.1 O 2 − δ model electrode. In our measurements, we have used the novel three electrode dual-chamber electrochemical cell developed in our previous work at different H 2 pressures and at different electrochemical conditions at around 650 ° C . The possible redox reactions on the anode surface ( N i 2 + ↔ N i 0, C e 4 + ↔ C e 3 + ) were investigated by HT-NAP-XPS technique simultaneously with electrochemical impedance spectroscopy measurements. The oxygen partial pressure in counter and reference electrode compartment was controlled at 0.2 bar. Changes in electronic structure of the C e 3 d and N i 2 p photoelectron spectra caused by electrode potential and H 2 pressure variations were observed and estimated by curve fitting procedure. The O 1 s and valence band photoelectron signals were used for depth probing of the chemical composition and redox changes at Ni-GDC and for studying the influence of the electrochemical polarization on the chemical state of Ni-GDC surface atoms. As a result changes in oxidation state of electrode surface atoms caused by electrode polarization and oxide ion flux through the membrane were detected with simultaneous significant variation of electrochemical impedance. Highlights: Operando NAP-XPS study of SOFC anode at different electrochemical conditions. Depth probing of operating anode showed variations in the electron spectra. Photoelectron spectra of Ni and Ce depend on pH2 and electrode polarization. Electronic structure and impedance of Ni(O)-GDC were monitored simultaneously. Used setup enables operando quantification of the level of redox processes.