Platinum (Pt) coated copper (Cu) nanowires (Pt/CuNWs)
are synthesized
by the partial galvanic displacement of Cu nanowires (CuNWs) with
a Pt loading of 18 wt %. Pt/CuNWs have an outer diameter of 100 nm,
a length of 25–40 μm, and a theoretical Pt layer thickness
of 2 nm. Cu templated Pt nanotubes (PtNTs (Cu)) with a wall thickness
of 11 nm, an outer diameter of 100 nm, and a length of 5–20
μm are synthesized by the complete galvanic displacement of
CuNWs. CuNWs are synthesized by the hydrazine reduction of Cu nitrate
in sodium hydroxide. Oxygen reduction reaction (ORR) and durability
experiments are conducted on Pt/CuNWs, PtNTs (Cu), silver templated
PtNTs (Ag), and carbon supported Pt nanoparticles (Pt/C) to evaluate
catalyst activity for use as proton exchange membrane fuel cell cathodes.
The ORR area activities of Pt/CuNWs and PtNTs (Cu) are 1.501 and 1.506
mA cmPt
–2, respectively. Pt/CuNWs produce
a dollar activity of 9.8 A $–1 (dollar activity
calculated from the DOE mass activity target for 2017–2020
of 0.44 A mgPGM
–1). Durability testing
of each catalyst shows improved retention of surface area and ORR
activity in comparison to Pt/C.
Platinum (Pt) coated palladium (Pd) nanotubes (Pt/PdNTs)
with a
wall thickness of 6 nm, outer diameter of 60 nm, and length of 5–20
μm are synthesized via the partial galvanic displacement of
Pd nanotubes. Pt coatings are controlled to a loading of 9 (PtPd 9),
14 (PtPd 14), and 18 (PtPd 18) wt % and estimated to have a thickness
of 1.1, 1.7, and 2.2 Pt atoms, respectively, if a uniform and continuous
coating is assumed. Oxygen reduction experiments have been used to
evaluate Pt/PdNTs, Pt nanotubes, Pd nanotubes, and supported Pt nanoparticle
activity for proton exchange membrane fuel cell cathodes. The dollar
and area (specific surface area) normalized ORR activities of Pt/PdNTs
exceed the United States Department of Energy (DOE) targets. PtPd
9, PtPd 14, and PtPd 18 produce dollar activities of 10.4, 9.4, and
8.7 A$–1, respectively; PtPd 9 exceeds the DOE dollar
activity target (9.7 A$–1) by 7%. Pt/PdNTs further
exceed the DOE area activity target by 40–43%.
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