Nanometer spectral long-acting catalyst capable of highly-efficiently decomposing organic pollutants under dark light and light-free conditions

The invention relates to a nanometer spectral long-acting catalyst capable of highly-efficiently decomposing organic pollutants under dark light and light-free conditions. The nanometer spectral long-acting catalyst is composed of, by weight, 100 parts of water and 3 to 20 parts of nanometer modified niobium oxide. The nanometer modified niobium oxide is prepared through the following steps: dissolving 3 to 10 parts by weight of niobium pentachloride in 100 parts by weight of absolute ethyl alcohol at room temperature so as to obtain an ethanol solution of niobium pentachloride, and carrying out standing for 5 to 30 min; adding 5 to 15 parts by weight of bismuth vanadate and 0.01 to 0.1 part by weight of blocked isocyanate into the ethanol solution of niobium pentachloride and carrying outuniform mixing so as to obtain a first mixed solution; dripping 100 parts by weight of an aqueous solution of ethanol into the first mixed solution at a speed of 3 to 10 ml/min while stirring the first mixed solution; adding