NOVELTY - Semiconductor quantum dot/titania nanotube catalyst material prepared by a layer-by-layer self-assembly method, is claimed. The catalyst material is formed by riveting a semiconductor quantum dot on the outer wall or only inner wall of a titania nanotube by using layer-by-layer self-assembly method based on chemical affinity.    USE - The semiconductor quantum dot/titania nanotube catalyst material is useful for degrading dyes and for photocatalytic degradation of water catalyst and solar cell electrode material (claimed).    ADVANTAGE - The method can be carried out at room temperature, and it is simple and easy.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for preparing the semiconductor quantum dot/titania nanotube catalyst material, comprising (i) weighing titania P25 (0.5 g) and mixing with 30 ml of aqueous sodium hydroxide solution (10 mol/l), performing ultrasonic treatment for 10 minutes at room temperature, transferring into a high-pressure hydrothermal kettle, sealing and performing hydrothermal reaction for 24 hours at 110-150 degrees C, naturally cooling to room temperature, filtering, washing the powder to be neutral by using deionized water and hydrochloric acid solution (0.1 mol/l), drying the powder obtained by filtering again for 10 hours at 90 degrees C to obtain a titania nanotube white powder with a quasi-anatase phase, (ii) adding the titania nanotube white powder obtained in step (i) into tetrahydrofuran solution of a coupling agent (0.2-1.0 mol/l), then adding 0.05 g of N,N'-dicyclohexylcarbodiimide (DCC) and stirring for 20 minutes to 12 hours at room temperature, filtering, washing the obtained precipitate by tetrahydrofuran and methanol, then placing the precipitate in a drying box at 50 degrees C for 10 hours to obtain a titania nanotube dry powder with inner and outer walls, where the coupling agent is 2-amino-ethanethiol or mercaptoacetic acid, and in the tetrahydrofuran solution of the coupling agent, the molar ratio of the coupling agent to the titania nanotube dry powder is 1:5-10, (iii) weighing 0.1 g of the titania nanotube dry powder obtained in step (ii) and adding in 25 ml of nitrate, chloride or acetate aqueous solution of palladium, cadmium or zinc (0.2-1 mol/l), mixing, stirring for 15-25 minutes at room temperature, filtering, washing, then placing the precipitate in a drying box at 50 degrees C to dry for 10 hours to obtain a powder, and (iv) soaking the powder obtained in step (iii) in 25 ml of sodium sulfide solution (0.1-0.8 mol/l), placing the powder on a magnetic stirrer, stirring for 15-25 minutes at room temperature, filtering, washing, then placing the precipitate at 50 degrees C in a drying box to dry for 10 hours to obtain a final semiconductor quantum dot/titania nanotube catalyst material formed by attaching layer-by-layer assembled semiconductor quantum dots on the inner and outer walls of the titania nanotube.