Platinum. It's one of the many banes of the fuel cell industry.
The catalytic membranes inside of methanol fuel cells are coated with it: it helps convert hydrocarbons into electric power. Platinum also helps eliminate particulates in the catalytic converter in your car. Although companies like Nanostellar are developing platinum substitutes, platinum remains the industry standard and it's not getting any cheaper. A few years ago, thieves would steal converters out of big rigs to get at platinum.
MIT researchers, led by associate professor of mechanical engineering and material science Yang Shao-Horn, have come up with a way to double the efficiency of fuel cells by creating textures on the membrane surface. Instead of forming a smooth layer, the platinum is arranged in a stair-step manner. This increases the reactive surface area of a finite amount of platinum and hence increases the power output. It's a classic nano play: increase the surface area and get better results. The platinum particles in fact get their stair-step arrangement because they are arranged on top of carbon nanotubes, the ultimate nano material.
Many have tried to promote methanol fuel cells for portable devices. They have yet to hit big. Oorja Protonics has taken a different tack. Instead of small fuel cells, it builds large scale methanol fuel cells for fork lifts. It has started selling some to Nissan.
Meanwhile, Osaka Gas and Panasonic have started selling methane fuel cells that can produce 1 kilowatt of power to homes in Japan.