It is an urgent task to seek other energetic resources or different energy conversion pathways to replace the burning of fossil fuels such as gasoline or diesel, due to the increasing worldwide energy demand and environmental concerns. One of the promising efforts is the development of fuel cell technology. Fuel cells exhibit exciting performance advantages for power generation by converting the chemical energy of a fuel directly into electricity. The intense interest in fuel cell technology stems from the fact that fuel cells are environmentally benign and extremely efficient. Among various types of fuel cells, the proton-exchange membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs) are appealing for automotive and portable electronic applications owing to their low operation temperatures.[1-3] Unfortunately, the high cost of Pt electrocatalyst still remain serious limitations to many applications. In this regard, it is rather challenging to explore more active and low-cost catalysts superior to the standard carbon-supported platinum (Pt/C) particle systems which are traditionally employed.
Precious metal, platinum (Pt), is traditionally used as a high-performance electrocatalyst for proton-exchange membrane fuel cells and fine chemical synthesis. Due to the high-cost and the scarcity of Pt, it is an urgent task to develop substitutes for the pure Pt-catalyst. To date, one of the most successful accomplishments is to partially substitute Pt using less expensive 3d-transition metals. It was also realized that the shape and surface structure of nanocrystals (NCs) plays a significant role in electrocatalytic activity and reaction durability. For instance, it has been reported that cubic Pt Nanocrystals possess unusual catalytic activity in oxidation reactions. As well-known, the electron density of state is actually sensitive with the surface structure, and different crystal facets could have diverse catalytic natures.
Platinum (Pt) nanoparticles (NPs) have been extensively studied because of their unique catalytic properties in various significant applications.[1-8] It has been realized that the catalytic activity of Pt Nanoparticles highly depends on the surface atomic arrangements on a particle.[9-11] For example, previous studies on oxygen reduction in adsorbing acidic solutions show that Pt {100} are more active than Pt {111} planes[12, 13] and the current density measured on Pt nanocubes is higher than that of truncated cubic Pt NCs.[14] As electrocatalysts, nanocubes of Pt[15-17] therefore received more attention than other morphologies such as multipod[18, 19] and one-dimensional nanostructure.[20, 21] To further reduce the overall use of expensive Pt and afford the potential of poisoning-resistance, Pt-based bimetallic NCs such as Pt—Ni,[22, 23] Pt—Co,[24-28] and Pt—Cu[29-32] have attracted an increasing interest. Moreover, recent reports indicate that electrocatalytic activities of some Pt-bimetallic NCs are superior to those of pure Pt metal.[25-28] A convenient and effective colloid method of synthesizing high-quality Pt—Cu nanocubes is provided.