A rare earth ion doped graphene / titanium dioxide composite material and preparation method thereof

Abstract

The invention discloses a rare earth ion doped graphene / titanium dioxide composite material, and the preparation method thereof is as follows: firstly, rare earth ions are doped into graphene sheets at high speed to prepare rare earth ion doped graphene; then, a mixed solution of anhydrous ethanol and glacial acetic acid is mixed with tetrabutyl titanate and recorded as liquid A; anhydrous ethanol, deionized water and concentrated hydrochloric acid are stirred evenly so that the solution pH is less than 3, and then rare earth ion doped graphene is added, and the solution is cooled by ultrasonic oscillation in a water bath and recorded as liquid B; liquid A and liquid B are mixed and reacted, and gel is obtained after standing and aging, and the gel is dried, ground and calcined to obtain rare earth ion doped graphene / titanium dioxide composite material powder. Because rare earth ions are doped between graphene sheets, the conductive properties of graphene are significantly changed, and the synergistic effect of the three greatly improves the photocatalytic ability of titanium dioxide.

Description

Technical Field

[0001] The present invention relates to the technical field of titanium dioxide modification, and in particular to a method for preparing modified titanium dioxide by doping rare earth ions between graphene sheets. Background Art

[0002] In recent years, due to the impact of industrial development and human life, environmental degradation, increasing carbon emissions and accumulation have become hot issues of social concern. Traditional treatment methods are difficult to eliminate high-stability pollution, such as trace organic pollutants in drinking water, persistent pollutants, endocrine disruptors and volatile organic compounds in the air. Semiconductor-based photocatalytic materials can be developed to alleviate and remove very small amounts of pollutants in air and water. Titanium dioxide, as a well-known photocatalytic material, is widely used in the elimination of environmental pollutants because of its strong photocatalytic activity, high photostability, low cost and non-toxicity, superior redox ability, reusability, simple structure and easy operation. However, as a photocatalyst, TiO2 has a large bandgap and a narrow light absorption wavelength range, mainly in the ultraviolet region. The proportion of sunlight utilization is low, accounting for only about 4% to 6%; the recombination rate of TiO2 semiconductor carriers is very high, and the photogenerated electron-hole pairs are easy to recombine, resulting in low quantum efficiency of photocatalytic reactions and low photocatalytic reaction rates. Summary of the invention

[0003] In view of the deficiencies of the prior art, the present invention dopes rare earth ions between graphene sheets and then composites them to prepare modified titanium dioxide, thereby improving the efficiency of the photocatalytic reaction and further improving the photocatalytic ability of titanium dioxide.

[0004] To achieve the above object, the present invention provides the following technical solution: a rare earth ion doped graphene / titanium dioxide composite material and a preparation method thereof, comprising the following steps:

[0005] A. Ionize the atoms of rare earth elements into ions, accelerate them at a voltage of tens to hundreds of kilovolts, and after obtaining a high speed, inject them into the surface of graphene powder placed in a vacuum target chamber to obtain rare earth ion graphene. After the graphene powder material is ion-implanted, the rare earth ions can destroy the van der Waals force between the graphene sheets due to the high injection speed, and are incorporated into the graphene sheets, causing a significant change in the conductive properties of the graphene;

[0006] B. At room temperature, first measure anhydrous ethanol, then use a pipette to transfer glacial acetic acid, stir evenly, and finally measure tetrabutyl titanate and mix evenly, which is recorded as liquid A;

[0007] C. At room temperature, measure anhydrous ethanol, add deionized water, and add a few drops of concentrated hydrochloric acid, stir evenly to make the solution pH <3, then add a certain mass of rare earth ion graphene, and perform ultrasonic oscillation in a water bath at a certain temperature for a certain period of time. The resulting solution after cooling is recorded as solution B;

[0008] D. stirring liquid A magnetically for a period of time, then dripping liquid B into liquid A at a uniform speed for a period of time, continuing to react for a period of time after the addition is completed, stopping stirring, and allowing the resulting mixed solution to stand for a period of time to age, thereby obtaining a rare earth ion-doped graphene / titanium dioxide composite material gel;

[0009] E. The above gel is dried, ground and calcined to obtain rare earth ion-doped graphene / titanium dioxide composite material powder.

[0010] Preferably, the rare earth element is terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium and heavy rare earth yttrium.

[0011] Preferably, the ratio of each component in step B is: V (anhydrous ethanol): V (glacial acetic acid): M (tetrabutyl titanate) = (1-2) mL: (1-2) mL: (2-4) mL.

[0012] Preferably, in step C, the ratio of each component is: V (anhydrous ethanol): M (rare earth ion graphene) = (1-2) mL: (5-10) g.

[0013] Preferably, the ultrasonic oscillation in step C, the magnetic stirring time, the time for liquid B to be dripped into liquid A, and the reaction time after the liquid B and liquid A are dripped into each other in step D are controlled within 30 min to 5 h.

[0014] Preferably, the water bath temperature in step C is 30°C to 100°C.

[0015] Preferably, in step D, the mass ratio of liquid A to liquid B is 1:1 to 1:3.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1) The traditional doping method only uses the rare earth ions in the solution to mechanically compound with graphene, which is difficult to overcome the van der Waals force between the graphene sheets and cannot completely enter between the graphene sheets, so it is impossible to obtain excellent conductive properties and photocatalytic effects; the technical solution of the present application injects rare earth ions at a higher speed, destroys the van der Waals force between the graphene sheets, and is doped between the graphene sheets, so that the conductive properties of graphene are significantly changed.

[0018] 2) Due to its unique two-dimensional structure, high specific surface area, good electron transport capability and flexible chemical functionalization properties, graphene added to materials can accelerate the migration of photogenerated carriers in photocatalytic reactions and inhibit the recombination of photogenerated electrons and photogenerated holes.

[0019] 3) The conductive properties of graphene are significantly changed by the incorporation of rare earth ions between graphene sheets. The synergistic effect of the three can significantly reduce the band gap, improve the efficiency of the photocatalytic reaction, and enhance the photocatalytic ability of titanium dioxide to a greater extent. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below by way of examples, which are not intended to limit the scope of the present invention.

[0021] Example 1

[0022] A. Ionize the atoms of the rare earth holmium element into ions, accelerate them at a voltage of 600 kilovolts, and inject them into the surface of graphene powder placed in a vacuum target chamber after obtaining a high speed; after the graphene powder material is implanted with holmium ions, the holmium ions can destroy the van der Waals force between the graphene sheets due to the high injection speed, and be incorporated into the graphene sheets, so that the conductive properties of the graphene will change significantly;

[0023] B. At room temperature, first measure 32.00 mL of anhydrous ethanol, and use a pipette to transfer 32.00 mL of glacial acetic acid, stir evenly, and finally measure 64.00 mL of tetrabutyl titanate and mix evenly with the above solution, which is recorded as solution A;

[0024] C. At room temperature, 32.00 mL of anhydrous ethanol was measured, a certain amount of deionized water was added, and several drops of concentrated hydrochloric acid were added. The mixture was stirred evenly so that the pH value of the solution was less than 3. 160 g of rare earth ion-doped graphene was weighed and added to the solution. The solution was ultrasonically shaken in a water bath at 60 ° C for 1 h. The resulting solution after cooling was recorded as solution B.

[0025] D. The A solution was magnetically stirred, and the B solution was uniformly added to the A solution within 30 min. After the addition was completed, the reaction was continued for 1 h, and the stirring was stopped. The mixed solution was allowed to stand for 12 h to obtain a holmium ion-doped graphene composite titanium dioxide gel;

[0026] E. The above gel is dried, ground and calcined to obtain holmium ion-doped graphene / titanium dioxide composite material powder.

[0027] Example 2

[0028] Referring to Example 1, the rare earth holmium element in step A is replaced with light rare earth lanthanum, europium and heavy rare earth ytterbium, yttrium to sputter the graphene powder surface, and different rare earth ions are doped in the graphene / titanium dioxide composite material powder to prepare.

[0029] Example 3

[0030] Referring to Example 1, the difference from Example 2 is that the graphene is not sputtered with holmium ions in step A, but directly prepared through steps B, C, D, and E to prepare graphene / titanium dioxide composite material powder.

[0031] Example 4

[0032] Referring to Example 1, different from the example, graphene was not added in the preparation process, but titanium dioxide powder was directly prepared.

[0033] Data Characterization

[0034] Accurately pipette a certain amount of 0.1g / mL methyl orange solution and scan it on a UV-visible spectrophotometer to draw the absorption curve.

[0035] Accurately pipette multiple portions of 100 mL of 0.1 g / mL methyl orange solution and mix them with the samples of each example at a mixing ratio of V (methyl orange solution): M (sample powder) = 10 mL: 1 g. The suspension is placed in a 1 L volumetric flask, diluted with distilled water and shaken to obtain a mixed solution for testing.

[0036] A cylindrical electric light source is used as a photochemical reactor. The central light source uses a 300W medium-pressure lamp, and the cold trap is made of quartz glass. A certain amount of the mixed solution to be tested is added to the reactor and mechanically stirred at a speed of 500r / min. After the mixture is evenly mixed, the mercury lamp is turned on and the timing is started. After 10min, the absorbance value is measured at the optimal wavelength. The residual chromaticity of methyl orange is calculated according to (ΔA / A0)*100% (ΔA and A0 are the optimal wavelength calculation values ​​of methyl orange solution before and after illumination, respectively. The specific results are shown in Table 1. Through comparative analysis, it can be seen that the performance of the sample prepared by adding rare earth sputtering is significantly better than that of the sputtered sample. At the same time, whether it is light rare earth lanthanum, holmium, europium, or heavy rare earth ytterbium and yttrium, its photocatalytic effect is more prominent.

[0037] Table 1 Residual chromaticity measurement table of each embodiment

[0038]

[0039]

[0040] The above description is a detailed description of a feasible embodiment of the present invention, but the embodiment is not intended to limit the scope of the patent application of the present invention. All equivalent changes or modified changes completed under the technical spirit suggested by the present invention are within the patent scope covered by the present invention.

Claims

1. A rare earth ion doped graphene / titanium dioxide composite material, characterized in that: The method for preparing the composite material comprises the following steps: A. Ionize the atoms of rare earth elements into ions, accelerate them at a voltage of tens to hundreds of kilovolts, and after obtaining a high speed, shoot them into the surface of graphene powder placed in a vacuum target chamber and incorporate them into the graphene sheet; B. At room temperature, first measure anhydrous ethanol, then use a pipette to transfer glacial acetic acid, stir evenly, and finally measure tetrabutyl titanate and mix evenly, which is recorded as liquid A; C. At room temperature, measure anhydrous ethanol, add deionized water, and add a few drops of concentrated hydrochloric acid, stir evenly to make the solution pH <3, then add a certain mass of rare earth ion graphene, and perform ultrasonic oscillation in a water bath at a certain temperature for a certain period of time. The resulting solution after cooling is recorded as solution B; D. stirring liquid A magnetically for a period of time, then dripping liquid B into liquid A at a uniform speed for a period of time, continuing to react for a period of time after the addition is completed, stopping stirring, and allowing the resulting mixed solution to stand for a period of time to age, thereby obtaining a rare earth ion-doped graphene / titanium dioxide composite material gel; E. drying, grinding and calcining the gel to obtain rare earth ion-doped graphene / titanium dioxide composite material powder; The rare earth elements are heavy rare earths of holmium, ytterbium and yttrium.

2. The rare earth ion-doped graphene / titanium dioxide composite material according to claim 1, characterized in that: The ratio of each component in step B is: V (anhydrous ethanol): V (glacial acetic acid): V (tetrabutyl titanate) = (1-2) mL: (1-2) mL: (2-4) mL.

3. The rare earth ion-doped graphene / titanium dioxide composite material according to claim 1, characterized in that: In the step C, the ratio of each component is: V (anhydrous ethanol): M (rare earth ion graphene) = (1-2) mL: (5-10) g.

4. The rare earth ion-doped graphene / titanium dioxide composite material according to claim 1, characterized in that: The ultrasonic oscillation in step C, the magnetic stirring time in step D, the time for liquid B to drip into liquid A, and the reaction time after liquid B and liquid A are dripped into are controlled within 30 minutes to 5 hours.

5. The rare earth ion doped graphene / titanium dioxide composite material according to claim 1, characterized in that: The water bath temperature in step C is 30°C to 100°C.

6. The rare earth ion doped graphene / titanium dioxide composite material according to claim 1, characterized in that: The mass ratio of the A liquid to the B liquid is 1:1 to 1:3.

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