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Enhanced oxygen-release/storage properties of Pd-loaded Sr 3 Fe 2 O 7-δ .

Authors :: Beppu K
Hosokawa S
Shibano T
Demizu A
Kato K
Wada K
Asakura H
Teramura K
Tanaka T
Source :: Physical chemistry chemical physics : PCCP [Phys Chem Chem Phys] 2017 May 31; Vol. 19 (21), pp. 14107-14113.
Publication Year :: 2017
Abstract: This study proves that a small amount of Pd loading (1 wt%) on Sr <subscript>3</subscript> Fe <subscript>2</subscript> O <subscript>7-δ</subscript> can dramatically enhance the oxygen-storage properties of Sr <subscript>3</subscript> Fe <subscript>2</subscript> O <subscript>7-δ</subscript> . The topotactic oxygen intake and release between Sr <subscript>3</subscript> Fe <subscript>2</subscript> O <subscript>6.75</subscript> and Sr <subscript>3</subscript> Fe <subscript>2</subscript> O <subscript>6</subscript> takes place in response to gas switching between an O <subscript>2</subscript> flow and H <subscript>2</subscript> flow, regardless of the presence or absence of Pd loading. The effect of Pd loading is significant for the oxygen-release process under H <subscript>2</subscript> atmosphere; that is, highly dispersed Pd metal nanoparticles sized less than 1 nm formed on Pd/Sr <subscript>3</subscript> Fe <subscript>2</subscript> O <subscript>7-δ</subscript> to promote H <subscript>2</subscript> dissociation, resulting in the improvement of the oxygen-release temperature and rate. Pd/Sr <subscript>3</subscript> Fe <subscript>2</subscript> O <subscript>7-δ</subscript> with a layered perovskite structure has a higher oxygen-release property at lower temperature than Pd/SrFeO <subscript>3-δ</subscript> with a perovskite phase without the layered structure. These facts indicate that the surface reaction as well as the crystal structure are responsible for the oxide ion mobility in perovskite structure, and also provide guidelines for designing novel oxygen-storage materials.