Carbon deposition on patterned nickel/yttria stabilized zirconia electrodes for solid oxide fuel cell/solid oxide electrolysis cell modes

• Distribution and structural features of deposited carbon on patterned Ni stripes.
• Deposited carbon could directly participate in the electrochemical reaction C(Ni) + O2−(YSZ) ↔ CO(Ni) + (YSZ) + 2e−.
• Deposited carbon in crystal graphitic carbon structure.

Carbon deposition on patterned nickel/yttria stabilized zirconia (YSZ) electrode of solid oxide cells operating in CO2/CO mixture gas at 750 °C with different discharging voltages was studied. Patterned Ni electrode is a useful and effective tool for in-situ observation of the carbon distribution and structural features. The elemental analysis by energy dispersive spectrometer observed that the electricity significantly promoted the carbon deposition on Ni stripes for SOEC, but weakened the deposition for SOFC. Besides, the carbon content near TPB was obviously higher than that in the middle of Ni stripes for SOEC, but lower than that in the middle for SOFC. It is speculated that the deposited carbon could directly participate in the electrochemical reaction C(Ni) + O2−(YSZ) ↔ CO(Ni) + (YSZ) + 2e− at TPB. The in-situ Raman spectra represented that the deposited carbon, produced or consumed by the carbon electrochemical reaction, was mainly in crystal graphitic carbon structure.