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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. 

Operando Raman spectroscopy and electrochemical techniques were used to examine carbon deposition on niobium doped SrTiO 3 (STN) based SOFC anodes infiltrated with Ni, Co, Ce 0.9 Gd 0.1 O 2 (CGO) and combinations of these materials. Cells were operated with CH 4 /CO 2 mixtures at 750 °C. Raman data shows that carbon forms on all cells under operating conditions when Ni is present as an infiltrate. Additional experiments performed during cell cool down, and on separate material pellets (not subject to an applied potential), show that chemically labile oxygen available in the CGO infiltrate will preferentially oxidize all deposited surface carbon as temperatures drop below 700 °C. These observations highlight the benefit of CGO as a material in SOFC anodes but more importantly, the value of operando spectroscopic techniques as a tool when evaluating a material's susceptibility to carbon accumulation. Solely relying on ex situ measurements will potentially lead to false conclusions about the studied materials’ ability to resist carbon and improperly inform efforts to develop mechanisms describing electrochemical oxidation and material degradation mechanisms in these high temperature energy conversion devices.