Operando characterization of metallic and bimetallic electrocatalysts for SOFC fuel electrodes operating under internal methane reforming conditions

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2022-03, Vol.10 (10), p.5550-5560
• Main Authors: Drasbæk, Daniel B., Welander, Märtha M., Traulsen, Marie L., Sudireddy, Bhaskar R., Holtappels, Peter, Walker, Robert A.
• Format: Article
• Language: English
• Subjects: Anodes; Bimetals; Carbon; Carbon dioxide; Catalytic activity; Cell anodes; Electrocatalysts; Electrochemical analysis; Electrochemical impedance spectroscopy; Electrochemistry; Electrode polarization; Electrodes; Fuels; Methane; Niobium; Operating temperature; Oxidation; Raman spectra; Raman spectroscopy; Reforming; Spectroscopy; Spectrum analysis
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/D1TA07299D

Linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and operando Raman spectroscopy were used to study the electrochemical performance and carbon tolerance of SOFCs operating with niobium doped SrTiO 3 (STN) anodes infiltrated with combinations of Ni, Co, and Ce 0.8 Gd 0.2 O 2 (CGO) added to improve catalytic activity. Cell anodes were exposed to fuel feeds of humidified H 2 , pure CH 4 and combinations of CO 2 and CH 4 at an operating temperature of 750 °C. Under pure CH 4 , Raman data show that carbon forms on all anodes containing Ni. In cells with CGO, deposited carbon results in a decreased polarization resistance. This behavior may be due to benefits conferred by CGO to the electrocatalytic activity of triple phase boundaries, presumably through improved oxide ion conductivity and/or due to carbon securing a better electrical connection in the electrodes. Raman spectra from Co-only containing anodes show no sign of carbon deposition. The absence of observable carbon together with low frequency processes observed in the EIS suggest that Co may play a role in oxidizing carbon before measurable amounts accumulate.