PEMFCs are attractive for powering cars because of their high efficiency, high power density, and zero emission. The biggest barrier to the widespread deployment of PEMFC cars has been the cost and durability of the Pt catalysts. Early Pt catalysts were large Pt particles that had high specific activity and durability, but were clearly not economical due to the very low specific surface area. To develop an economical Pt catalyst the effort has been focused on Pt nanoparticles (PtNP). To increase mass activity, the ultimate measure of cost, the prevailing wisdom for a long period of time was to increase specific surface area by reducing the diameter of the PtNP. However as the diameter of PtNP decreases the specific activity also reduces, leading to unchanged or even lower mass activity. Small PtNPs are also not durable due to dissolution, aggregation and Oswald ripening¹⁵. To overcome this difficult tradeoff between high specific activity-low specific area (as in Pt macrowires and macroparticles) and low specific activity -high specific area (as in PtNP of 2-3 nm diameter), we have been working on the concept of Pt nanotubes (PtNTs) and their derivatives that can exhibit the favorable features of the Pt macrowires/macroparticles (high specific activity and durability) and the PtNPs (high specific activity) in the same structure¹⁵. We later made porous PtNTs to increase the Pt utilization¹⁷; replaced the Ag nanowire (AgNW) template¹⁵ with CuNWs to reduce cost^{18, 19}; and synthesized Pt thin layer on CuNWs (Pt/CuNWs) to improve mass activity further.^{18, 19}