Palladium and Gold Nanotubes as Oxygen Reduction Reaction and Alcohol Oxidation Reaction Catalysts in Base

Abstract

Palladium (PdNTs) and gold nanotubes (AuNTs) were synthesized by the galvanic displacement of silver nanowires. PdNTs and AuNTs have wall thicknesses of 6 nm, outer diameters of 60 nm, and lengths of 5-10 and 5-20 μm, respectively. Rotating disk electrode experiments showed that the PdNTs and AuNTs have higher area normalized activities for the oxygen reduction reaction (ORR) than conventional nanoparticle catalysts. The PdNTs produced an ORR area activity that was 3.4, 2.2, and 3.7 times greater than that on carbon-supported palladium nanoparticles (Pd/C), bulk polycrystalline palladium, and carbon-supported platinum nanoparticles (Pt/C), respectively. The AuNTs produced an ORR area activity that was 2.3, 9.0, and 2.0 times greater than that on carbon-supported gold nanoparticles (Au/C), bulk polycrystalline gold, and Pt/C, respectively. The PdNTs also had lower onset potentials than Pd/C and Pt/C for the oxidation of methanol (0.236 V), ethanol (0.215 V), and ethylene glycol (0.251 V). In comparison to Pt/C, the PdNTs and AuNTs further demonstrated improved alcohol tolerance during the ORR.

Carbon‐Nanotubes‐Supported Pd Nanoparticles for Alcohol Oxidations in Fuel Cells: Effect of Number of Nanotube Walls on Activity

“…In addition to the significant promotion effect of addition of Ni‐Zn, Au, Sn, W, and oxides such as Co 3 O 4 , etc., to Pd‐based electrocatalysts for alcohol oxidation reactions,2, 7, 46, 61 the present studies demonstrate clearly that the electrocatalytic activity of Pd NPs can also be significantly enhanced by manipulating the quantum properties and electron‐tunneling effect of inner tubes of CNTs supports.…”

“…Direct alcohols fuel cells (DAFCs) have attracted considerable attention due to its high volumetric energy density of alcohols and ease of storage and transport of liquid fuels in comparison with hydrogen 1. 2 Pd nanoparticles (NPs) are the most common electrocatalysts in DAFCs because of their high activity for alcohol oxidation reactions in alkaline solutions 3–7. However, Pd is a precious noble metal whose high cost impedes the commercialization of DAFCs.…”

An Overview of One-Dimensional Metal Nanostructures for Electrocatalysis

“…The structure of the resulting Ag/Au/AgCl was changed from a core-shell solid wire to a nanotube as the HAuCl 4 concentration increased, which exhibited good oxygen reduction reaction activity, stability, and ethanol tolerance in alkaline media. Recently, Pd and Au nanotubes were prepared by the galvanic displacement of Ag nanowires and were examined as oxygen reduction catalysts in alkaline media [88]. The Pd nanotubes produced an area-based activity that was at least two times greater than those with Pd/C, bulk polycrystalline Pd, and Pt/C.…”

Template synthesis of palladium nanotubes and their electrocatalytic properties

“…Hexagonal Pd nanosheets with plasmonic and high catalytic properties can be synthesized by a CO-confined growth method at low temperature [13]. Usually, Pd hollow structures can be synthesized from the spheric or tubular templates [17][18][19][20][21][22][23][24][25]. For example, Pd hollow sphere array can be prepared by electrodeposition of Pd on the SiO 2 spheres [16].…”

“…Vertical free-standing Pd nanotubes can be obtained based on the alumina membrane under an electric potential [22]. Pd nanotubes can also be synthesized by the one-dimensional template under a high temperature [23].…”