Three-dimensional hexagonal GDC interlayer for area enhancement of low-temperature solid oxide fuel cells

• Three-dimensional hexagonal GDC interlayer is fabricated with enhanced active area by a factor of 1.7.
• Electrode resistance with 3-D interlayer decreased by half of that of plane interface.
• Superior exchange current density was obtained compared to previous studies of interfaces between electrode and electrolyte.

A three-dimensional hexagonal gadolinium-doped ceria (GDC) interlayer is fabricated to enhance the cathodic surface area of low-temperature solid oxide fuel cells (LT-SOFCs). By using modified nanosphere lithography method, 3-D nanostructure is successfully fabricated. As a result of the nanostructuring, the 3-D hexagonal GDC interlayer has a 70% increase in cathodic surface area. Electrochemical impedance spectroscopy reveals a 2-fold decrease in the electrode resistance compared with a plane cell, resulting in a current–voltage behavior with a 60% higher peak power density. The superior electrode reaction is attributed to the large surface area (~ 1.7 times larger) due to the 3-D hexagonal cathodic interlayer. This novel fabrication method can be applied to almost all kinds of LT-SOFC structures, including large-scale and substrate-supported platforms, and thereby it will contribute to commercializing LT-SOFCs.