TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Method: The removing step involves combining the platinum nanoparticle with a metal salt in a solution. The method additionally involves removing platinum atoms from step regions and kinks in the platinum nanoparticle; replacing platinum atoms located at the step regions and kinks with atoms of the second metal; at least one of stirring the solution and heating the solution, after combining the platinum nanoparticle with the metal salt; and recycling the replaced platinum atoms dissolved into the solution. The replaced platinum atoms are dissolved into the solution. The platinum nanoparticles are removed from the solution after approximately 5 minutes. The second metal atoms occupy approximately 5-75% of total surface area of the nanoparticle, after replacing the platinum atoms. The method involves either(A) method A: combining platinum nanoparticle having several edges, corners, and terraces (26) including surface atoms and surface defects, and second metal in solution, where an oxidation reduction reaction occurs between platinum and ions of the second metal so that platinum atoms from corner regions, edge regions, and surface defects of the nanoparticle are dissolved and replaced with atoms of the second metal; and removing the platinum nanoparticle from the solution before platinum surface atoms on the terraces are replaced with atoms of the second metal; or(B) method B: combining platinum nanoparticles and metal salt in a solution, where each nanoparticle includes several terraces, edges and corners, and platinum atoms at the corners and the edges of the nanoparticle have a lower electrode potential than an electrode potential of a metal in the metal salt; and maintaining the nanoparticles in the solution for a time to dissolve the platinum atoms at corner regions and edge regions of the nanoparticles and replace the dissolved platinum atoms with atoms of the metal from the metal salt, where the platinum surface atoms on the terraces are unchanged.In the method (A), the surface defects on the nanoparticle include at least one of a step atom, a kink atom, and a step adatom. The method (A) additionally involves combining the nanoparticle with surfactant, prior to combining the platinum nanoparticle and the second metal in a solution, such that the surfactant adsorbs on at least a portion of the terraces of the nanoparticle; and synthesizing the platinum nanoparticles, prior to combining the platinum nanoparticles and a metal salt in a solution. In the method (B), the terraces on each nanoparticle include platinum surface atoms, platinum step atoms and platinum kink atoms, and maintaining the nanoparticles in the solution for a time to dissolve the platinum atoms at corner regions and edge regions of the nanoparticle includes dissolving the platinum step atoms and the platinum kink atoms; and replacing the dissolved platinum atoms with atoms of the metal from the metal salt. The method (B) additionally involves recycling the platinum atoms dissolved in the solution. The approximately 5-75% of a total surface area of nanoparticle is replaced with the metal from the metal salt, after removing the nanoparticles from the solution. Preferred Components: The platinum nanoparticle is selected from cubic nanoparticles, tetrahedral nanoparticles, cubo-octahedral nanoparticles, icosahedral nanoparticles, spherical nanoparticles, quasi-spherical nanoparticles, rhombohedral nanoparticles, and truncated octahedral nanoparticles. The second metal is selected from gold, iridium, rhodium, ruthenium, rhenium, osmium, palladium and/or silver. The platinum nanoparticle include at least one of platinum atoms and a platinum alloy having at least one metal selected from transition metals from fourth, fifth and sixth row of the periodic table. The platinum nanoparticle has a diameter of approximately 0.5-100 nanometers. The second metal has a standard electrode potential greater than a standard electrode potential of platinum, or less than or equal to standard electrode potential of platinum. In the method (M2), the platinum nanoparticle is supported on substrate. The solution includes at least one of an acidic solution, an alkaline solution, and non-aqueous solution. EXAMPLE - No suitable example is given.