Abstract: We provide a single-atom catalyst comprising nanostructures of a conductive material and a plurality of single-atom metal sites dispersed on the surface of each of the nanostructures. A method of manufacture of such catalyst is also provided. It relies on the electrodeposition or drop casting of the nanostructures of a conductive material on a substrate, followed by the adsorption and electrochemical reduction of complex ions comprising a single atom of each of one or more metal on the surface of the nanostructures.

Abstract: A method of making metal nanostructures having a nanometer size in at least one dimension includes preparing an aqueous solution comprising a cation of a first metal and an anion, and mixing commercial elemental powder particles of an elemental second metal having a greater reduction potential than the first metal with the aqueous solution in an amount that reacts and dissolves all of the second metal and precipitates the first metal as metal nanostructures. The temperature and concentration of the aqueous solution and the selection of the anions and the second metal are chosen to produce metal nanostructures of a desired shape, for example ribbons, wires, flowers, rods, spheres, hollow spheres, scrolls, tubes, sheets, hexagonal sheets, rice, cones, dendrites, or particles.

Abstract: Platinum particles have been formed as porous, hollow tubular dendrites by using silver dendrite particles in a galvanic replacement reaction conducted in an aqueous solution of a platinum compound. The dendritic platinum particles have been found useful as catalysts and particularly useful as a hydrogen-oxidation electrocatalyst and/or an oxygen-reduction catalyst in a polymer electrolyte membrane fuel cell.

Abstract: Platinum particles have been formed as porous, hollow tubular dendrites by using silver dendrite particles in a galvanic replacement reaction conducted in an aqueous solution of a platinum compound. The dendritic platinum particles have been found useful as catalysts and particularly useful as a hydrogen-oxidation electrocatalyst and/or an oxygen-reduction catalyst in a polymer electrolyte membrane fuel cell.

Abstract: A method of making metal nanostructures having a nanometer size in at least one dimension includes preparing an aqueous solution comprising a cation of a first metal and an anion, and mixing commercial elemental powder particles of an elemental second metal having a greater reduction potential than the first metal with the aqueous solution in an amount that reacts and dissolves all of the second metal and precipitates the first metal as metal nanostructures. The temperature and concentration of the aqueous solution and the selection of the anions and the second metal are chosen to produce metal nanostructures of a desired shape, for example ribbons, wires, flowers, rods, spheres, hollow spheres, scrolls, tubes, sheets, hexagonal sheets, rice, cones, dendrites, or particles.