Highly Efficient CH4-assisted CO2 Electrolysis for Syngas Production in a Quasi-Symmetric Ni-ceramic Electrolyzer

Solid oxide electrolysis cells (SOECs) can efficiently utilize renewable energy to achieve efficient CO 2 reduction and CH 4 reforming for syngas production. In this work, a high-performance quasi-symmetric Ni-based electrolyzer with Ni -Gd 0.1 Ce 0.9 O 2 (GDC) porous cathode and Ni -Y 0.16 Zr 0.84 O 1.92 (YSZ) microchannel anode, is designed for efficient CO 2 electrolysis and electrochemical oxidation of CH 4 . The electrolytic current density of SOEC reaches 3.2 A cm-2 at the voltage of 1.5 V for CH 4-assisted CO 2 electrolysis. Highly efficient and stable electrolysis of CO 2 is achieved at the thin porous Ni-GDC cathode without external protective gases through the regulation of methane concentration and increasing the electrolysis current. The designed SOECs exhibits a stable operation for 400 h at a highly electrolysis current density of 2 A cm-2 without external protective gases and does not experience detrimental effects from the carbon deposits, despite the presence of a small amount of carbon deposits observed in the anode channels confirmed by the EDS analysis. This study has demonstrated that the design of quasi-symmetric Ni-ceramic electrolyzer is a highly efficient strategy for achieving electrochemical reforming of CH 4 with CO 2 .