TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The liquid vehicle comprises water. The precursor medium comprises 1-10 wt.% substrate precursor.    TECHNOLOGY FOCUS - METALLURGY - Preferred Components: The intermediate particles comprise substrate particles and metal-containing compositions disposed on substrate particles. The substrate particles comprise carbon microparticles having a d50 value (by volume) of 1-20 microns. The average distance between adjacent alloy nanoparticles on a given substrate particle is 1-10 nm. The metal-containing compositions are formed from first and second metal precursors. At least one of the metal-containing compositions comprises elemental metal or metal oxide. The alloy nanoparticles are formed from metals derived from first and second metal precursors. The first metal precursor comprises platinum, and the second metal precursor comprises second metal. The alloy nanoparticles comprise a solid solution of platinum and second metal. The precursor medium may contain third metal precursor comprising third metal different from second metal, and fourth metal precursor comprising fourth metal different from second and third metals. The second, third and fourth metals are nickel, cobalt, iron, copper, manganese, chromium, ruthenium, rhenium, molybdenum, tungsten, vanadium, zinc, titanium, zirconium, tantalum, iridium, palladium, or gold. The alloy nanoparticles have an average particle size of 1-10 (preferably 3-5 or 1-3) nm. The alloy nanoparticles comprise disordered alloy. The alloy nanoparticles comprise a solid solution of platinum, manganese and iron; a solid solution of platinum, palladium and manganese; a solid solution of platinum, palladium, nickel and cobalt; a solid solution of platinum, cobalt and copper in amounts represented by formula PtxCoyCuz, where x, y and z are the respective mole fractions of platinum, cobalt and copper such that they are within the compositional area defined by four points of specified ternary diagram; a solid solution of platinum, cobalt and iron in amounts represented by formula PtxCoyFez, where x, y and z are the respective mole fractions of platinum, cobalt and iron such that they are within the compositional area defined by four points of ternary diagram; a solid solution of platinum, iron and copper in amounts represented by formula PtxFeyCuz, where x, y and z are the respective mole fractions of platinum, iron and copper such that they are within the compositional area defined by six or four points of ternary diagram; a solid solution of platinum, nickel and copper in amounts represented by formula PtxNiyCuz, where x, y and z are the respective mole fractions of platinum, nickel and copper such that they are within the compositional area defined by four points of ternary diagram; a solid solution of platinum, nickel and iron in amounts represented by the formula PtxNiyFez, where x, y and z are the respective mole fractions of platinum, nickel and iron such that they are within the compositional area defined by points four of ternary diagram; a solid solution of platinum, palladium and copper in amounts represented by formula PtxPdyCuz, where x, y and z are the respective mole fractions of platinum, palladium and copper such that they are within the compositional area defined by six or four points of ternary diagram; a solid solution of platinum, palladium and cobalt in amounts represented by formula PtxPdyCoz, where x, y and z are the respective mole fractions of platinum, palladium and cobalt such that they are within the compositional area defined by points four of ternary diagram; or a solid solution of platinum, nickel and cobalt in amounts represented by formula PtxNiyCoz, where x, y and z are the respective mole fractions of platinum, nickel and cobalt such that they are within the compositional area defined by points four of ternary diagram. EXAMPLE - Tetra amine platinum nitrate (1.02 g), cobalt nitrate hexahydrate (0.64 g) and copper nitrate hemipentahydrate (1.3 g) were dissolved in distilled water (80 ml), followed by addition of carbon suspension (18.2 g), containing 22 wt.% Vulcan XC72R(RTM: Not defined) in water. The resulting mixture was converted to aerosol by ultrasonic spray nozzle using air as carrier gas in a spray conversion apparatus. The aerosol was processed in a horizontal tube furnace set up at 550degreesC. A black powder with composition of 20% Pt25Co10Cu65/carbon was obtained. The powder was further reduced under 5% hydrogen balanced with nitrogen atmosphere at 300degreesC for 2 hours. The composition of nanoparticles in the electrocatalyst particles contained platinum (0.25 mole%), cobalt (0.21 mole%) and copper (0.54 mole%). The mass activity of electrocatalyst particles at 0.55 V versus standard calomel electrode in a three-electrode, half-cell liquid electrolyte configuration was 42.98 mA/mg Pt.