▎ 摘　　要

NOVELTY - Controlling crystal plane structure exposed on surface of titanium dioxide quantum dots, comprises e.g. (i) adding tetrabutyl titanate to absolute ethanol, stirring, adding hydrochloric acid solution while stirring to obtain solution A, (ii) dripping a mixed solution prepared from absolute ethanol and deionized water to solution A to obtain solution B, stirring solution B to a sol state, where the volume ratio of absolute ethanol and deionized water in mixed solution is 1:1, and the volume ratio of the mixed solution and absolute ethanol is 1:1 or 1:2, (iii) keeping the sol at 160-200 degrees C for 2-4 hours to obtain brown titanium dioxide powder, (iv) dispersing the brown powder in anhydrous ethanol, naturally settling to a significant layering, taking the upper layer solution, centrifuging, washing with deionized water, and vacuum-drying to obtain titanium dioxide quantum dots, and (v) placing titanium dioxide quantum dots under the protection of an inert atmosphere. USE - The quantum dots are useful for preparing composite photocatalyst (claimed). ADVANTAGE - The method: introduces more oxygen vacancies on the surface of the prepared titanium dioxide quantum dots to improve the interface properties of the titanium dioxide composite material; utilizes surface oxygen vacancy defects as an interaction medium to combine with two-dimensional materials; and prepares a zero-dimensional-two-dimensional composite photocatalyst with high photocatalytic activity. DETAILED DESCRIPTION - Controlling crystal plane structure exposed on surface of titanium dioxide quantum dots, comprises (i) adding tetrabutyl titanate to absolute ethanol, stirring, adding hydrochloric acid solution while stirring to obtain solution A, where the volume ratio of tetrabutyl titanate, absolute ethanol and hydrochloric acid solution is (3-6):(18-20):(0.5-0.8), (ii) dripping a mixed solution prepared from absolute ethanol and deionized water to solution A to obtain solution B, stirring solution B to a sol state, where the volume ratio of absolute ethanol and deionized water in the mixed solution is 1:1, and the volume ratio of the mixed solution and the absolute ethanol in the step (i) is 1:1 or 1:2, (iii) keeping the sol prepared in the step (ii) at 160-200 degrees C for 2-4 hours to obtain brown titanium dioxide powder, (iv) dispersing the brown powder obtained in step (iii) in anhydrous ethanol, naturally settling to a significant layering, taking the upper layer solution, centrifuging, washing with deionized water, and vacuum-drying to obtain titanium dioxide quantum dots, and (v) placing titanium dioxide quantum dots under the protection of an inert atmosphere, and heat-treating at 160-200 degrees C for 1-5 hours to obtain titanium dioxide quantum dots rich in oxygen vacancy defects. INDEPENDENT CLAIMS are also included for: (1) titanium dioxide quantum dot material prepared by the performing the above-mentioned method, comprising a crystal grain size of 5-20 nm, where the crystal plane structure exposed on the surface of the titanium dioxide quantum dots is (001) crystal plane or (101) crystal plane; (2) preparing composite photocatalyst by using titanium dioxide quantum dots and graphene oxide, (a) dispersing the flake graphene oxide solution in deionized water, preparing solution C by performing ultrasonic treatment for 1-2 hours, where the concentration of graphene oxide solution is 3-4 mg/ml, and the volume ratio of graphene oxide solution and deionized water is (0.2-0.3):(40-50), (b) adding the titanium dioxide quantum dot material to the solution C, and continuously performing ultrasonic treatment for 1-2 hours to obtain solution D, where the dosage ratio of the titanium dioxide quantum dot material and the solution C is (0.2-0.3) g: (40-50) ml, (c) vacuum-drying the solution D to obtain powder, and (d) placing the powder in an inert atmosphere and heat-treating at 250-350 degrees C for 1-6 hours to obtain a zero-dimensional-2D composite photocatalyst; (3) zero-dimensional-two-dimensional composite photocatalyst prepared by the performing the above-mentioned preparation process of a composite photocatalyst constructed of titanium dioxide quantum dots and graphene oxide; (4) preparing composite photocatalyst by using titanium dioxide quantum dots and manganese dioxide, comprising (A) dispersing flaky manganese dioxide into deionized water, preparing solution E by ultrasonic treatment for 1-2 hours, where the dosage ratio of manganese dioxide and deionized water is (0.1-0.2) g:(40-50) ml, (B) adding the titanium dioxide quantum dot material to the solution E, continuously performing ultrasonic treatment for 1-2 hours to prepare the solution F, where the dosage ratio of the titanium dioxide quantum dot material and the solution E is (0.2-0.3) g: (40-50) ml, (B) vacuum-drying the solution F to obtain powder, and (D) placing the powder in an inert atmosphere and heat-treating at 250-350 degrees C for 1-6 hours to obtain a zero-dimensional-two-dimensional composite photocatalyst; and (5) zero-dimensional-two-dimensional composite photocatalyst prepared by performing the above-mentioned preparation process of a composite photocatalyst constructed of titanium dioxide quantum dots and manganese dioxide.