TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Method: The method (M1) further involves heating the transition metal-carbon nanofiber catalyst in an ammonia atmosphere at 700-1500 degrees C for 1-3 hours to modify with nitrogen atoms and then, after adding a hydrocarbon, heating in a hydrocarbon atmosphere at 700-1500 degrees C for 1-3 hours; activating the resulting transition metal-carbon nanofiber catalyst in a steam atmosphere at 200-300 degrees C for 1-3 hours; and finely grinding the resulting transition metal-carbon nanofiber catalyst. In the method (M1), mixing of the polymer precursor with the organic solvent is performed at 40-60 degrees C for 3-24 hours, mixing of the polymer precursor mixture with the transition metal precursor is performed at 40-60 degrees C for 5-24 hours, and the electrospinning of the spinning solution is performed at a voltage of 18-60 kV and a flow rate of 1-10 ml/hour. The stabilizing of the transition metal-nanofiber is performed by heating the transition metal-nanofiber from room temperature at a rate of 1-5 degrees C/minute and keeping at a final temperature of 250-350 degrees C for 1-2 hours. The carbonizing of the transition metal-nanofiber intermediate is performed by heating the transition metal-nanofiber intermediate in a nitrogen atmosphere at a rate of 3-7 degrees C/minute and keeping at a final temperature of 700-1000 degrees C for 30 minutes to 3 hours. The fine grinding of the transition metal-carbon nanofiber catalyst is performed by pulverizing the transition metal-carbon nanofiber catalyst using a ball mill at a rate of 100-300 rpm for 30 minutes to 4 hours and drying with hot air of 100-150 degrees C or in vacuum, or by pulverizing using an ultrasonic pulverizer with a power of 10-100 W for 1-5 minutes. Preferred Components: The transition metal precursor is an alkoxide-based precursor comprising a transition metal selected from iron (Fe), cobalt (Co), nickel (Ni), copper (Cu) or a combination of at least two of its. The transition metal precursor is selected from iron (II) acetylacetonate, iron (III) acetylacetonate, cobalt (II) acetylacetonate, cobalt (III) acetylacetonate, nickel (II) acetylacetonate, nickel (III) acetylacetonate, copper (II) acetylacetonate, copper (III) acetylacetonate, metal acetate, metal sulfide or metal chloride. The spinning solution comprises transition metal precursor (0.1-2 wt.%) and polymer precursor mixture (98-99.9 wt.%).    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The organic solvent is water, ethanol, N,N-dimethylformamide (DMF), acetone, benzene, toluene, hexane, acetonitrile or tetrahydrofuran.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The polymer precursor is selected from polyacrylonitrile (PAN), polyamide (PA), polyacrylamide (PAA), polyurethane (PU), polyetherimide (PEI), polyvinylpyrrolidone (PVP) or polybenzimidazole (PBI). The polymer precursor mixture comprises polymer precursor (5-30 wt.%) and organic solvent (70-95 wt.%). EXAMPLE - Preparation of transition metal-carbon nanofiber catalyst was carried as follows: a polyacrylonitrile (10 wt.%) was mixed with and dissolved in dimethylformamide (90 wt.%) at 40 degrees C for 4 hours to prepare a polymer solution. To 80 wt.% of the polymer precursor solution, iron (II) acetylacetonate (0.2 wt.%) and cobalt (II) acetylacetonate (0.2 wt.%) were added. After completely dissolving at 50 degrees C for 6 hours, a spinning solution was prepared. The spinning solution was spun at a flow rate of 3 ml/hour for 10 hours by applying a high voltage of 24 kV between a syringe and a rotating drum spaced by 15 cm, so as to form a nanofiber on the drum surface. The electrospinning condition was 25 degrees C and 30% relative humidity. For oxidative stabilization, the electrospun nanofiber was heated at a rate of 1 degrees C/minute and then heat-treated at 280 degrees C in an oxygen atmosphere for 1 hour. Then, the nanofiber was carbonized at 800 degrees C in a nitrogen atmosphere for 1 hour after heating at a rate of 5 degrees C/minute to obtain a carbon nanofiber matrix. The obtained carbon nanofiber catalyst was activated at 250 degrees C in a steam atmosphere for 2 hours to form an activated carbon nanofiber catalyst. The catalyst had a specific surface area of 700 m2. The obtained carbon nanofiber catalyst was pulverized using a ball mill at 200 rpm for 2 hours, and dried with hot air of 120 degrees C. As a result, a carbon nanofiber catalyst with an average length of 15 mu m was obtained.