Nanomaterial-based catalysts are usually heterogeneous catalysts broken up into nanoparticles in order to speed up the catalytic process. The extremely small size of the particles maximizes the surface area exposed to the reactant, allowing more reactions to occur at the same time, thus speeding up the process.

Much research on nanomaterial-based catalysts has to do with maximizing the effectiveness of the catalyst coating in fuel cells. Platinum

Platinum nanoparticles

Platinum nanoparticles are usually in the form of a suspension or colloid of sub-micrometre-sized particles of platinum in a fluid, usually water. A colloid is technically defined as particles which remain suspended without forming an ionic, or dissolved solution...

 is currently the most common catalyst for this application, however, it is expensive and rare, so a lot of research has been going into maximizing the catalytic properties of other metals by shrinking them to nanoparticles in the hope that someday they will be an efficient and economic alternative to platinum. Gold nanoparticles also exhibit catalytic properties, despite the fact that bulk gold

Gold

Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...

is unreactive.