Platinum Coated Copper Nanowires and Platinum Nanotubes as Oxygen Reduction Electrocatalysts

Abstract

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.