Methods and devices for catalyzing reactions, e.g., in a metal-air electrochemical cell, are disclosed. In some instances, a porous positive electrode of the metal-air electrochemical cell includes a metal to catalyze a reaction at the electrode (e.g., oxidation of one or more metal-oxide species). The metal can be disposed as nanoparticles, and/or be combined with a second metal. Other aspects are directed to devices and methods that can generally promote a chemical reaction (e.g., an oxidation/reduction reaction) such as the formation of platinum containing nanoparticles that can be used to catalyze electrochemical reactions.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
 This invention was made with Government support under Grant No. DE-AC02-05CH11231, awarded by the Department of Energy. The Government has certain rights in this invention.