An apparatus and method for the synthesis and treatment of electrocatalyst particles in batch or continuous fashion is provided. In one embodiment, the apparatus is comprised of a three-electrode cell which includes a cell body electrode, a reference electrode, and a counter electrode. A slurry containing non-noble metal ions and a plurality of particles is introduced into the apparatus. During operation an electrical potential is applied and the slurry is stirred. When particles in the slurry collide with the electrically conductive region of the cell body electrode the transferred charge facilitates deposition of an adlayer of the desired metal. In this manner film growth can commence on a large number of particles simultaneously. After the non-noble metal ions are deposited onto the particles, they are displaced by noble-metal ions by galvanic displacement. This process is especially suitable for forming catalytically active layers on nanoparticles for use in energy conversion devices.
STATEMENT OF GOVERNMENT LICENSE RIGHTS
 This invention was made with Government support under contract number DE-AC02-98CH10886, awarded by the U.S. Department of Energy. The Government has certain rights in the invention.