TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Method: The method further comprises: adding a base solution to the mixture of the support ink and the noble metal precursor solution prior to feeding the mixture to the spiral glass tube reactor; and filtering and drying the formed supported noble metal nanoparticles. The heating step comprises exposing the spiral glass tube reactor to microwave heat at 100-200 degrees C (preferably 150 degrees C) or millimeter waves. Preferred Components: The base solution comprises a hydroxide of sodium or potassium. The noble metal nanoparticles comprise nanoparticles of platinum, ruthenium, palladium, gold, silver, rhenium, rhodium, iridium and/or osmium. The noble metal precursor comprises an oxide, a halide, a nitrite, a sulfate, or a complex of platinum, ruthenium, palladium, gold, silver, rhenium, rhodium, iridium and/or osmium. The support comprises one or more carbon material comprising carbon black, carbon nanotube, carbon fiber, graphene, graphite and carbon mesosphere. The noble metal loading based on the total mass of the noble metal nanoparticles and the support is greater than or equal to 60 wt.%, preferably 75 wt%. The average noble metal nanoparticle size is 1.8 nm.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The noble metal precursor solution further comprises a polybasic carboxylic acid, preferably citric acid, tartaric acid, malic acid, oxalic acid, or its salt. The polybasic carboxylic acid comprises citric acid or a citrate of sodium or potassium. The solution of the first polyhydric alcohol and the solution of the second polyhydric alcohol are the same. The first polyhydric alcohol and the second polyhydric alcohol comprise ethylene glycol. EXAMPLE - 0.6 g of Carbon powder was dispersed in 60 ml of ethylene glycol to make carbon ink. 1.08 g of hexachloroplatinic acid was dissolved in 100 ml of ethylene glycol and 1.6 g of citrate acid was dissolved in 50 ml of ethylene glycol, respectively. Before the carbon ink was added, the citrate acid solution was mixed with metallic precursor solution and adequately stirred for one and a half hour. Sodium hydroxide was added into ethylene glycol to prepare 1 M solution, and used to change the above mixed ink pH level to 13. After adequate stirring, the mixed ink was heated to 150 degrees C and kept refluxing for 1 hour to get the noble metal precursor reduced adequately. The reduced black mixed slurry was centrifuged to separate the solid after pH level was adjusted to 3-4 by hydrochloric acid aqueous solution. The obtained solid was dried in vacuum oven at 60 degrees C overnight to obtain 40 wt.% of platinum on carbon (Pt/C) catalyst.