Study on the surface modification of submicron gadolinium-doped ceria electrolyte on nanoporous substrate using atomic layer deposition technique

Abstract

Oxygen-ion conducting and thin film solid oxide fuel cells fabricated by separate vacuum deposition methods (atomic layer deposition (ALD) and sputtering) were electrochemically evaluated at temperatures below 500oC and their material properties were investigated by means of chemical, structural, and microstructural analyses. An anodic aluminum oxide (AAO) membrane with well-arrayed nanopores was used as a reliable substrate to stack up the thin film components of the bottom anode, the top cathode, and the intermediate electrolyte. ALD-deposited yttria-stabilized zirconia of a few tens of nanometers directly deposited onto the anode-coated AAO substrate efficaciously prevented gadolinium-doped ceria (GDC) thin film electrolyte from being exposed to a high-temperature reducing atmosphere, a condition which lowers the physicochemical stability of ceria. Thinning of the ALD YSZ-blocked GDC thin film electrolytes on the anode-coated AAO substrate led to faster oxygen reduction reaction kinetics through electrolyte nanostructuring originating from substrate-dependent growth and an increase in the surface grain boundary density at the cathode/electrolyte interface. The nanothin and dense ALD-deposited platinum (Pt) deposited onto the nanostructured GDC thin film electrolyte exhibited highly catalytic activity, showing that it is capable of replacing the physical vapor deposition-deposited thicker Pt thin film cathode.