Zn-doped CeO2 composite photocatalytic material and preparation method thereof

Abstract

The application provides a Zn-doped CeO2 photocatalytic material and a preparation method thereof. The preparation method comprises the following steps: 1) adding cerium nitrate, zinc chloride and citric acid into water to obtain a mixed solution; 2) performing ultrasonic treatment on the mixed solution in step 1) to obtain a uniform solution; 3) placing the uniform solution in step 2) in an oven to dry to obtain a dry gel; 4) grinding the dry gel obtained in step 3) into a powder; and 5) placing the powder obtained in step 4) into a muffle furnace to calcine, so as to obtain the photocatalytic material with Zn-doped CeO2. The method can realize rapid synthesis of the Zn-doped CeO2 photocatalytic material, and the photocatalytic material has good photocatalytic performance. Moreover, the preparation method is easy to operate, the traditional complicated process is omitted, and the Zn-CeO2 photocatalytic material can be preferably applied to industrialized mass production.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photocatalytic materials, in particular to a Zn-doped CeO2 composite photocatalytic material and a preparation method thereof. BACKGROUND

[0002] Photocatalytic oxidation technology is one of the important means for environmental problems in recent years. Because of its green environmental protection in operation, mild reaction conditions, and the production of active oxygen with high redox potential in the reaction process, photocatalytic oxidation has been widely concerned by various countries.

[0003] Cerium dioxide (CeO2) as a typical rare earth oxide, has been widely concerned due to its low price, large industrial production, good chemical stability, good wear and abrasion resistance, and the ability to degrade various pollutants. Although CeO2 has abundant oxygen vacancies, unique electronic configuration, and chemical and thermal stability, it has certain application in the fields of heat, electricity and photocatalysis, but its energy utilization rate is low, and the electron and hole are easy to recombine quickly, resulting in a wide band gap, which leads to unsatisfactory catalytic activity.

[0004] Zn-doped metal oxide nanoparticles have been widely used in optical and antibacterial activity. The radius of Zn ion is similar to that of cerium ion, and the doping can promote the separation of electron hole of CeO2 and delay the separation time; it can also widen the band gap and enhance the absorption range of light, thus improving the utilization rate of light energy.

[0005] So far, the method for preparing Zn-doped CeO2 composite material is mainly water / solvent thermal method, and some use in-situ growth method. No matter what kind of method, most of them use high-temperature and high-pressure reaction kettles as reaction containers. Because the reaction conditions in such containers are unstable and difficult to control, the actual reaction amount of the reagent is lower than the theoretical value, so the reagent yield is not good during the preparation process, resulting in waste. SUMMARY

[0006] In view of this, the present application aims to improve the traditional sol-gel method for synthesizing CeO2 and related materials. The present application provides a new method for easily operating, quickly synthesizing, and realizing good photocatalytic performance of Zn-doped CeO2 photocatalytic material, which can be applied to industrialized mass production of Zn-doped CeO2 photocatalytic material.

[0007] The technical scheme of the present application is as follows:

[0008] A preparation method of Zn-doped CeO2 photocatalytic material, comprising the following steps:

[0009] 1) adding cerium nitrate, zinc chloride and citric acid into water to obtain a mixed solution;

[0010] 2) ultrasonic treatment of the mixed solution in step 1) to obtain a homogeneous solution;

[0011] 3) drying of the homogeneous solution in step 2) in an oven to obtain a dry gel;

[0012] 4) grinding of the dry gel in step 3) into a powder;

[0013] 5) calcination of the powder in step 4) in a muffle furnace to obtain a photocatalytic material with Zn-doped CeO2.

[0014] Further, in step 1), the molar ratio of cerium nitrate to citric acid is 1:2-5.

[0015] Further, in step 1), the mass of zinc chloride is 10%-50% of the mass of cerium nitrate, preferably 20%-50%.

[0016] Further, in step 2), the ultrasonic dispersion time is 10-30 min, the ultrasonic frequency is 35-45 KHz, and the power is 200-400 W.

[0017] Further, in step 3), the drying temperature is 90-120℃, and the drying time is 2-4 h.

[0018] Further, in step 5), the calcination temperature is 450-650℃, and the calcination time is 2-6 h.

[0019] Further, the cerium nitrate is at least one of hexahydrate cerium nitrate and trihydrate cerium nitrate.

[0020] Further, the citric acid is at least one of monohydrate citric acid and anhydrous citric acid.

[0021] A Zn-doped CeO2 photocatalytic material is prepared by any one of the preparation methods of the present application.

[0022] Compared with the prior art, the present application has the following beneficial effects:

[0023] 1) The present application provides an easy-to-operate method that eliminates the traditional complex process, and the prepared material has excellent photocatalytic performance and can be well applied to the industrialized mass production of Zn-doped CeO2 photocatalytic materials.

[0024] 2) Compared with the traditional hydrothermal method and solvothermal method for preparing Zn-doped CeO2 photocatalytic material, the method uses cerium nitrate as a precursor and zinc chloride as a zinc doping body, utilizes the condensation reaction of hydroxyl and carboxyl in citric acid to form an organic skeleton, fixes cerium ions and zinc ions, and directly synthesizes Zn-doped CeO2 photocatalytic material at high temperature, thereby saving the complex gas-liquid environment of controlling a high-temperature and high-pressure reaction kettle and realizing rapid synthesis of Zn-doped CeO2 photocatalytic material.

[0025] 3) The prepared material has better photocatalytic performance than CeO2 in the experiment of photocatalytic degradation of rhodamine B. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 : The photocatalytic degradation efficiency comparison chart of rhodamine B of Example 1, Example 2, Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4. DETAILED DESCRIPTION

[0027] In order to better understand the technical content of the present application, specific examples are provided below to further illustrate the present application.

[0028] The experimental methods used in the embodiments of the present application are conventional methods unless otherwise specified.

[0029] The materials, reagents, etc. used in the embodiments of the present application can be obtained from commercial channels unless otherwise specified.

[0030] Example 1 Preparation of Zn-doped CeO2 photocatalytic material

[0031] The preparation method of the Zn-doped CeO2 photocatalytic material includes the following steps:

[0032] Step 1: 0.8684 g (0.002 mol) of cerium nitrate hexahydrate (Ce(NO3)3·6H2O), 10% (0.0868 g) of zinc chloride (ZnCl2) of the former, and 1.2608 g (0.006 mol) of citric acid monohydrate (C6H8O7·H2O) are added to ionized water to obtain a mixed solution.

[0033] Step 2: The mixed solution of step 1 is ultrasonically treated for 15 min under ultrasonic waves (350 W, 40 kHz) to obtain a uniform solution.

[0034] Step 3: The uniform solution of step 2 is transferred to an oven at 105°C, and the drying time is 2 h to obtain a dry gel.

[0035] Step 4: The dry gel obtained in step 3 is ground into a powder.

[0036] Step 5: The powder obtained from step 4 was placed in a muffle furnace, the holding temperature was 500℃, and the holding time was 2h. The Zn-CeO2 photocatalytic material was obtained.

[0037] Example 2 Preparation of Zn-doped CeO2 photocatalytic material

[0038] The preparation method of the Zn-doped CeO2 photocatalytic material comprises the following steps:

[0039] Step 1: 0.8684g (0.002mol) of cerium nitrate hexahydrate (Ce(NO3)3·6H2O), 30% (0.2605g) of zinc chloride (ZnCl2) in mass of the former, and 1.2608g (0.006mol) of citric acid monohydrate (C6H8O7·H2O) were added to ionized water to obtain a mixed solution.

[0040] Step 2: The mixed solution in step 1 was ultrasonically treated for 15min under ultrasonic waves (350W, 40kHz) to obtain a uniform solution.

[0041] Step 3: The uniform solution in step 2 was transferred to an oven at 105℃, and the drying time was 2h to obtain a dry gel.

[0042] Step 4: The dry gel obtained in step 3 was ground into a powder.

[0043] Step 5: The powder obtained from step 4 was placed in a muffle furnace, the holding temperature was 500℃, and the holding time was 2h. The Zn-CeO2 photocatalytic material was obtained.

[0044] Comparative Example 1 Catalytic performance under ultraviolet lamp irradiation conditions

[0045] The power and emission wavelength of the ultraviolet lamp were 30W and 253.7nm ultraviolet light. The photocatalytic experiment was only carried out under the ultraviolet lamp, and no photocatalytic material was added.

[0046] Comparative Example 2 Preparation of CeO2 by sol-gel method

[0047] No zinc chloride was added in this comparative example.

[0048] The preparation method of the CeO2 by sol-gel method comprises the following steps:

[0049] Step 1: 0.8684g (0.002mol) of cerium nitrate hexahydrate (Ce(NO3)3·6H2O) and 1.2608g (0.006mol) of citric acid monohydrate (C6H8O7·H2O) were added to ionized water to obtain a mixed solution.

[0050] Step 2: The mixed solution in step 1 was ultrasonically treated for 15min under ultrasonic waves (350W, 40kHz) to obtain a uniform solution.

[0051] Step 3: The homogeneous solution in step 2 was transferred into an oven at 105 °C for 2 h to obtain a dry gel.

[0052] Step 4: The dry gel obtained in step 3 was ground into a powder.

[0053] Step 5: The powder obtained in step 4 was placed into a muffle furnace at a holding temperature of 500 °C for 2 h to obtain a CeO2material.

[0054] Preparation of Zn-doped CeO2photocatalytic material

[0055] The main difference with Example 2 is that in this comparative example, no zinc chloride was added, but zinc nitrate hexahydrate was added.

[0056] Preparation of Zn-doped CeO2photocatalytic material includes the following steps:

[0057] Step 1: 0.8684 g (0.002 mol) of cerium nitrate hexahydrate (Ce(N03)3-6H20), 30% by mass of the former (0.2605 g) of zinc nitrate hexahydrate (Zn(N03)2-6H20) and 1.2608 g (0.006 mol) of citric acid monohydrate (C6H8O7-H20) were added to ionized water to obtain a mixed solution.

[0058] Step 2: The mixed solution in step 1 was ultrasonicated for 15 min under ultrasonic waves (350 W, 40 kHz).

[0059] Step 3: The homogeneous solution in step 2 was transferred into an oven at 105 °C for 2 h to obtain a dry gel.

[0060] Step 4: The dry gel obtained in step 3 was ground into a powder.

[0061] Step 5: The powder obtained in step 4 was placed into a muffle furnace at a holding temperature of 500 °C for 2 h to obtain a Zn-CeO2photocatalytic material.

[0062] Preparation of Zn-doped CeO2photocatalytic material

[0063] The main difference with Example 2 is that in this comparative example, no citric acid monohydrate was added, but lactic acid was added.

[0064] Preparation of Zn-doped CeO2photocatalytic material includes the following steps:

[0065] Step 1: 0.8684 g (0.002 mol) of cerium nitrate hexahydrate (Ce(NO3)3-6H2O), 30% (0.2605 g) of zinc chloride (ZnCl2) by mass of the former, and 0.448 mL (0.006 mol, relative density 1.206) of lactic acid (C3H6O3) were added to ionized water to obtain a mixed solution.

[0066] Step 2: The mixed solution in Step 1 was subjected to ultrasonic treatment (350 W, 40 kHz) for 15 min to obtain a uniform solution.

[0067] Step 3: The uniform solution in Step 2 was transferred to an oven at 105°C, and dried for 2 h to obtain a dry gel.

[0068] Step 4: The dry gel obtained in Step 3 was ground into a powder.

[0069] Step 5: The powder obtained in Step 4 was placed in a muffle furnace, and heat-treated at 500°C for 2 h to obtain a Zn-CeO2 photocatalytic material.

[0070] Test Example - Catalytic performance under ultraviolet light irradiation conditions

[0071] 1.1 Test method

[0072] The materials prepared in Test Examples 1-2 and Comparative Examples 2-4 were used in a photocatalytic decolorization experiment of 10 mg / L rhodamine B dye solution under 30 W, 253.7 nm ultraviolet light, and Comparative Example 1 was used as a blank control.

[0073] Test group 1-5: The materials prepared in Test Examples 1-2 and Comparative Examples 2-4 were used in a photocatalytic decolorization experiment of 10 mg / L rhodamine B dye solution under 30 W, 253.7 nm ultraviolet light, and Comparative Example 1 was used as a blank control.

[0074] Test group 1-5: 25 ml of 100 mg / L rhodamine B and deionized water were added to a beaker to prepare 250 ml of 10 mg / L rhodamine B solution, and then 250 mg of the material prepared in Test Examples 1-2 and Comparative Examples 2-4 was added, and photocatalytic decolorization was performed under 30 W, 253.7 nm ultraviolet light, and the absorbance at 554 nm was measured.

[0075] Blank control group (i.e., Comparative Example 1): 25 ml of 100 mg / L rhodamine B and deionized water were added to a beaker to prepare 250 ml of 10 mg / L rhodamine B solution, and photocatalytic decolorization was performed directly under 30 W, 253.7 nm ultraviolet light, and the absorbance at 554 nm was measured.

[0076] 1.2 Test results

[0077] From the above results, it can be seen that the Zn-CeO2 photocatalytic material prepared in Test Examples 1-2 has a higher photocatalytic activity than the materials prepared in Comparative Examples 2-4. Figure 1It can be seen that the embodiment 2 shows excellent photocatalytic activity in the experiment of photocatalytic decolorization of 10 mg / L rhodamine B dye solution under 30 W, 253.7 nm ultraviolet light. It is calculated that the reaction processes of the embodiment 1, the embodiment 2, the comparative example 1, the comparative example 2, the comparative example 3, the comparative example 4 meet the first-order kinetic model of photocatalytic reaction, and the corresponding reaction rate constants are 0.246 h -1 , 0.564 h -1 , 0.042 h -1 , 0.036 h -1 , 0.276 h -1 , 0.264 h -1 . The comparative example 1 hardly affects the photocatalytic process, and the photocatalytic rates of the embodiment 1 and the embodiment 2 are increased by about 6.8 times and 15.7 times, respectively, compared with the comparative example 2, i.e., the CeO2 prepared by the sol-gel method. Compared with the embodiment 2, the photocatalytic rates of the comparative example 3 and the comparative example 4 are obviously decreased.

[0078] In addition, in other embodiments,

[0079] In step 1), the molar ratio of cerium nitrate to citric acid is 1:2-5.

[0080] In step 1), the mass of zinc chloride is 10%-50% of the mass of cerium nitrate.

[0081] In step 2), the ultrasonic dispersion time is 10-30 min, the ultrasonic frequency is 35-45 KHz, and the power is 200-400 W.

[0082] In step 3), the drying temperature is 90-120 DEG C, and the drying time is 2-4 h.

[0083] In step 5), the calcination temperature is 450-650 DEG C, and the calcination time is 2-6 h.

[0084] By adjusting the above ranges, the purposes of the present application can be achieved.

[0085] The above only describes the preferred embodiments of the present application and should not be used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a Zn-doped CeO2 photocatalytic material, characterized in that, The method comprises the following steps: 1) adding cerium nitrate, zinc chloride and citric acid into water to obtain a mixed solution; 2) performing ultrasonic treatment on the mixed solution in step 1) to obtain a uniform solution; 3) placing the uniform solution in step 2) in an oven for drying to obtain a dry gel; 4) grinding the dry gel obtained in step 3) into powder; 5) placing the powder obtained in step 4) into a muffle furnace for calcination to obtain a photocatalytic material with Zn-doped CeO2; in step 1), the molar ratio of the cerium nitrate to the citric acid is 1:2-5, and the mass of the zinc chloride is 20%-50% of the mass of the cerium nitrate; in step 2), the ultrasonic dispersion time is 10-30 min, the ultrasonic frequency is 35-45 KHz, and the power is 200-400 W; in step 3), the drying temperature is 90-120 DEG C, and the drying time is 2-4 h; in step 5), the calcination temperature is 450-650 DEG C, and the calcination time is 2-6 h; the Zn-doped CeO2 photocatalytic material is used for ultraviolet photocatalytic degradation of rhodamine B.

2. The production method according to claim 1, characterized by, the cerium nitrate is cerium nitrate hexahydrate.

3. The preparation method according to claim 1, characterized in that, the citric acid is at least one of citric acid monohydrate and anhydrous citric acid.

4. A Zn-doped CeO2 photocatalytic material, characterized in that, obtained by the preparation method in claim 1.

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