TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The nanofiber includes anatase type nanofiber with niobium precursor content of 0.1-20 wt.% and specific surface area of 10-90 m2/g; and rutile type nanofiber with niobium precursor content of 20-60 wt.% and specific surface area of 90-130 m2/g. The titanium precursor includes at least one of titanium ethoxide, titanium butoxide, titanium isopropoxide, titanium tetra isopropoxide, titanium chloride, titanium dichloride, titanium trichloride, titanium tetrachloride, titanium bromide and titanium oxysulfate. The amount of titanium precursor in the precursor solution is 0.1-15 wt.%. The dispersing agent includes at least one of acetic acid, nitric acid, hydrochloric acid and sulfuric acid. The amount of dispersing agent in the precursor solution is 1-80 wt.%. The amount of stabilizer in the precursor solution is 4-30 wt.%. The niobium precursor includes at least one of niobium ethoxide, niobium pentoxide, niobium chloride and niobium nitride. The amount of niobium precursor is 0.1-60 wt.% based on the titanium precursor. The nanofiber has specific surface area of 10-130 m2/g and diameter of 30-150 nm. Preferred method: The method comprises, (S1) preparing titanium precursor solution by mixing titanium precursor, dispersing agent, stabilizer and solvent, (S2) adding niobium precursor in the titanium precursor solution obtained from the step (S1), (S3) producing niobium-doped titanium dioxide nanofiber by electrospinning the precursor solution obtained from the step (S2), and (S4) crystallizing by calcining the niobium-doped titanium dioxide nanofiber obtained from the step (S3). The electrospinning step is carried out under the voltage of 10-20 kV with the precursor solution supplying rate of 0.01-0.05 ml/l. The calcining step is carried out at 400-600 degrees C for 3-7 hours.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The solvent includes at least one of N,N-dimethylformamide, ethanol, methanol, propanol, butanol, tetrahydrofuran, acetone, isopropyl and alcohol.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The stabilizer includes at least one of polyvinylpyrrolidone, polymethylmethacrylate, polyvinyl alcohol, polyvinyl acetate, polystyrene, polyacrylonitrile and polyvinylidene fluoride. EXAMPLE - 12 wt.% Titanium(IV) isopropoxide, 12 wt.% vinylpyrrolidone, 2.4 wt.% acetic acid and remaining amount of N, N-dimethylformamide were mixed and stirred to dissolve at room temperature for 60 minutes to obtain the titanium precursor solution. Then 10 wt.% niobium(V) ethoxide was added to the titanium precursor solution to obtain the precursor solution. The obtained precursor solution was injected with a feed rate of 0.04 ml/hour, electrospun with 14.5 kV voltage, calcined at 500 degrees C for 5 hours and crystallized to obtain the anatase-type niobium-doped titanium dioxide nanofiber with specific surface area of 87.3 m2/g.