Nanoporous silver cathode surface-treated by aerosol-assisted chemical vapor deposition of gadolinia-doped ceria for intermediate-temperature solid oxide fuel cells

Abstract

Herein, a nanoporous silver surface treated with gadolinia-doped ceria (GDC) is evaluated as a cathode for intermediate-temperature solid oxide fuel cells operating below 500 °C. For uniform surface treatment on the porous silver, aerosol-assisted chemical vapor deposition (AACVD) is used; it is a non-vacuum process and is considered as an economical alternative to the expensive vacuum-environment thin-film fabrication methods. Consequently, a uniform coating of AACVD GDC on the Ag surface is successfully achieved, which is confirmed by high-resolution transmission electron microscopy. The optimized amount of AACVD GDC enhances fuel cell performance compared to cells with bare Ag, in terms of the power and long-term stability measured by current–voltage characteristics, electrochemical impedance spectroscopy, and potentiostatic amperometry. This performance is even more significant than that from the cell with a platinum cathode, which, to our best knowledge, is known as the best-performing catalyst for solid oxide fuel cells in the intermediate- and low-temperature regimes. The power enhancement is attributed to the improved kinetics with the GDC surface coating; moreover, this oxide decoration is proven effective in preventing the thermal agglomeration of Ag, as confirmed by the morphology comparison before and after the long-term test.