Heat-treatment induced evolution of the morphology and microstructure of zirconia prepared from chloride solutions during

Nafion/Surface Modified Ceria Hybrid Membranes for Fuel Cell Application

“…The following solutions were used as ceria precursors: 0.01 M Ce(NO 3 ) 3 ( Before the modification, Nafion-117 membranes were conditioned by sequential boiling in 3% H 2 O 2 solution, 5% HCl solution, and deionized water for 2 h. Then, they were placed in a ceria precursor solution for 1 h, treated with a diluted aqueous ammonia solution and re-conditioned by keeping in 5% HCl solution and deionized water at 25 • C for 1 h. Hybrid membranes prepared using Ce(NO 3 ) 3 and (NH 4 ) 2 Ce(NO 3 ) 6 solutions were treated with 0.2 or 1 M sulfuric acid or phosphoric acid for modification of the surface of ceria in membrane pores and channels with sulfonic or phosphoric acid groups, respectively. Since oxides of polyvalent elements prepared by precipitation from aqueous precursor solutions are usually nanocrystalline, their surface contains a significant amount of ions sorbed from solutions [42,43]. It can be assumed that ceria precipitation from cerium sulfate solution will lead to a modification of the surface of obtained oxide by sulfonic acid groups.…”