Synthesis, characterization, and testing of Pt-NPG catalysts developed by de-alloying of electrodeposited CuxAu(1−x) thin films. (January 2017)

• Record Type: Journal Article
• Authors: Xia, Jiaxin; Achari, Innocent; Ambrozik, Stephen; Dimitrov, Nikolay
• Is Part Of: Materials research bulletin. Volume 85(2017)
• Page Start: 1
• Page End: 9
• Publication Date: 2017-01
• Subjects: Pt -- Nanoporous Au -- Thin film -- Cu-Au alloys -- De-alloying -- Platinization -- Catalysis -- Formic acid oxidation; Materials -- Periodicals; Crystal growth -- Periodicals; Matériaux -- Périodiques; Cristaux -- Croissance -- Périodiques; Crystal growth; Materials; Periodicals; 620.11
• DOI: 10.1016/j.materresbull.2016.08.032
• Languages: English
• ISSNs: 0025-5408

Abstract

Graphical abstract: Cu-Au thin film de-alloying curves of Cu-Au alloys with three different compositions. Inset Images: SEM micrographs of 5:1 (red) and 1:1 (green) alloys. Inset Plot: Formic acid oxidation after 500 cycles for 5:1 (red) and 1:1 (green) alloys. Highlights: Nanoporous Au (NPG) is synthesized by de-alloying of electrodeposited Cu-Au thin films. Composition independent critical potentials are observed in the de-alloying of said films. The NPG in this work features three-fold larger surface area than Ag-Au counterparts. Pt coatings render the NPG films highly active formic acid (FA) oxidation catalysts. The developed Pt-NPG catalysts feature mass activity of 3–5 A/mg in FA oxidation. Abstract: Electrodeposited Cux Au(1−x) thin films with different compositions have been found to undergo selective dissolution (de-alloying) in three specific potential ranges unlike their bulk counterparts that are known to de-alloy at composition dependent critical potentials. The general potential trend associated with co-existence of different thermodynamically stable alloy phases suggests increasing de-alloying rate in positive direction with the decreasing Cu content in the alloy. Following de-alloying, the resulting nanoporous Au (NPG) thin films exhibit significant surface area (SA) development, manifested by about three-fold increase in comparison with de-alloyed Agx Au(1−x) precursor counterparts. SEM characterization have seconded the SA results by revealing a finer structure of the NPG films which feature pores and ligaments of less than 10 nm. Formic acid oxidation tests suggest that the platinization of accordingly synthesized NPG thin films leads to the synthesis of catalysts exhibiting initial mass activities of 3–5 A mg −1 (combined Pt-Au catalyst) and withstanding more than 2500 potential cycles.