Disclosure of Invention
The invention aims to provide C-QDs-Fe2O3/TiO2The preparation method of the composite photocatalyst is simple, easy to operate and low in cost.
Another object of the present invention is to provide a C-QDs-Fe2O3/TiO2A composite photocatalyst, which is prepared by passing Fe2O3And modifying, and adding carbon quantum dots to obtain the visible light responsive composite photocatalyst with high photocatalytic efficiency.
The technical problem to be solved by the invention is realized by adopting the following technical scheme.
The invention provides C-QDs-Fe2O3/TiO2The preparation method of the composite photocatalyst is characterized by comprising the following steps:
s1, dispersing starch in absolute ethyl alcohol, adding glucose, and violently stirring to obtain a first mixed solution;
s2, dissolving ferric salt in absolute ethyl alcohol to obtain a second mixed solution, dropwise adding the second mixed solution into the first mixed solution, adding acetone after dropwise adding is finished, and stirring and mixing to obtain a third mixed solution;
s3, adding a titanium liquid into the third mixed solution, and then dropwise adding water and absolute ethyl alcohol to obtain a mixture, wherein the titanium liquid is a mixed solution of ethylene glycol, tetrabutyl titanate and absolute ethyl alcohol;
s4, transferring the mixture to a reaction kettle, carrying out heat treatment at 80-200 ℃ for 3-48 h, separating, washing and drying to obtain a dried product, and carrying out treatment on the dried product at 300-800 ℃ for 1-10 h under the protection of inert gas to obtain the composite photocatalyst.
The invention also provides C-QDs-Fe2O3/TiO2The composite photocatalyst is prepared by the preparation method.
The embodiment of the invention has the beneficial effects that:
to TiO 22Carrying out Fe2O3Doping to make TiO2The band gap is narrowed, and the visible light activity is higher. The material obtained from starch, glucose and the like at low cost is used as the source of the carbon quantum dot, the carbon quantum dot has excellent photostability, and good specificity of photoinduced electron transfer, Fe2O3And the carbon quantum dots are doped together, so that the recombination of electrons and holes is effectively prevented, and the photocatalytic activity of the product is greatly improved. Has excellent photocatalytic activity under visible light, no pollution, no toxicity and low cost.
The nano composite photocatalyst is obtained through hydrothermal reaction and low-temperature calcination, the preparation method is simple, various parameters are easy to control, the particle size of the obtained composite photocatalyst is about 5-20 nm, and the utilization rate of visible light can be further improved by utilizing the coupling effect among nano particles.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
The following examples of C-QDs-Fe of the present invention2O3/TiO2The composite photocatalyst and the preparation method thereof are concretely explained.
The embodiment of the invention provides C-QDs-Fe2O3/TiO2The preparation method of the composite photocatalyst comprises the following steps:
and S1, dispersing the starch in absolute ethyl alcohol, adding glucose, and stirring vigorously to obtain a first mixed solution.
Further, in the preferred embodiment of the invention, the mass ratio of the starch to the glucose is 1: 1-2, and more preferably, the mass ratio of the starch to the glucose is 1: 1. Starch and glucose are both carbohydrates, and are cheap and easily available.
Further, the feed-liquid ratio of the starch to the absolute ethyl alcohol is 1-3 g/ml.
Further, in the step, the speed of vigorous stirring is 5000-10000 r/min. And the starch and the glucose are stirred vigorously to form a first mixed solution with uniform quality.
S2, dissolving the ferric salt in the absolute ethyl alcohol to obtain a second mixed solution. And dropwise adding the second mixed solution into the first mixed solution, adding acetone after dropwise adding is finished, and stirring and mixing to obtain a third mixed solution.
Further, in a preferred embodiment of the present invention, the iron salt is selected from one or more of ferric nitrate, ferric sulfate and ferric chloride, and more preferably, the iron salt is selected from ferric nitrate.
Further, in the second mixed solution, the feed-liquid ratio of the ferric nitrate to the absolute ethyl alcohol is 0.01-0.05 g/ml.
Further, in the step, the second mixed solution is dripped into the first mixed solution at the speed of 1-3 drops/second. And stirring while dripping to ensure that the second mixed solution is stably and uniformly mixed into the first mixed solution to carry out Fe treatment3+Forming a carbohydrate coating structure.
Further, the volume ratio of the acetone to the second mixed solution is 0.2-1: 1. After adding acetone, stirring and reacting for 30-60 min at the speed of 5000-10000 r/min.
Further, the mass ratio of the iron salt to the starch is 1: 6-50. More preferably, the ratio is 1: 10-30. Regulating C-QDs and Fe by regulating the mass ratio of carbohydrates2O3The doping amount of the photocatalyst is optimized, so that the synergistic effect of the two components is optimized, and the photocatalytic performance is better.
And S3, adding the titanium liquid into the third mixed solution, and then dropwise adding water and absolute ethyl alcohol to obtain a mixture, wherein the titanium liquid is a mixed solution of ethylene glycol, tetrabutyl titanate and absolute ethyl alcohol.
Further, in the step, the titanium liquid is ethylene glycol, tetrabutyl titanate and absolute ethyl alcohol in a volume ratio of 1-5: 3-10: 10-20.
Further, the volume ratio of the tetrabutyl titanate to the second mixed solution is 0.3-1: 1.
Further, in the step, the dropping speed of the water and the absolute ethyl alcohol is 1-3 drops/second, and stirring is carried out while dropping.
S4, transferring the mixture to a reaction kettle, carrying out heat treatment at 80-200 ℃ for 3-48 h, separating, washing and drying to obtain a dried product, and carrying out treatment on the dried product at 300-800 ℃ for 1-10 h under the protection of inert gas to obtain the composite photocatalyst.
Further, in the reaction kettle, the temperature is firstly increased to 80-100 ℃, heat treatment is carried out for 3-5 hours, then the temperature is increased to 160-180 ℃, and heat treatment is carried out for 9-16 hours. The hydrothermal reaction process is effectively controlled, the reaction is firstly carried out at a lower temperature and then carried out at a higher temperature, the reaction is promoted to be carried out, the substances are fully decomposed, the nano particles with uniform shapes can be formed, the crystallization degree of the composite photocatalyst is effectively controlled, and the composite photocatalyst with a better structure is obtained.
Further, in this step, the inert gas is nitrogen. Preferably, under the protection of nitrogen, the temperature is increased to 300-350 ℃ at the speed of 15-20 ℃/min, the temperature is maintained for 1-2 h, then the temperature is increased to 500-600 ℃ at the speed of 2-6 ℃/min, and the temperature is maintained for 3-6 h. The temperature is controlled by a program, the temperature is quickly raised to a lower temperature for processing, and then the temperature is slowly raised to a higher temperature, so that a more complete crystal structure is formed.
Further, the method also comprises the step of grinding the product after cooling to room temperature.
The embodiment of the invention provides C-QDs-Fe2O3/TiO2The composite photocatalyst is prepared by the preparation method.
The features and properties of the present invention are described in further detail below with reference to examples.
Example 1
This example provides a C-QDs-Fe2O3/TiO2The preparation method of the composite photocatalyst comprises the following steps:
(1) dispersing 4g starch in 20ml absolute ethyl alcohol, adding 4g glucose, and vigorously stirring (8000 rpm) for 10min to obtain a mixed solution.
(2) 0.2g of ferric nitrate was dissolved in 10ml of anhydrous ethanol, and the solution was added to the mixture in (1) at a rate of 2 drops/sec. Then, 8ml of acetone was added to the above solution and stirred for 50min at 8000 rpm to obtain a mixed solution.
(3) Preparing a titanium solution containing 4mL of ethylene glycol, 8mL of tetrabutyl titanate and 18mL of absolute ethyl alcohol, adding the titanium solution into the mixed solution in the step (2), and then adding 6mL of deionized water and 12mL of absolute ethyl alcohol at the speed of 2 drops per second while stirring to obtain a mixed solution.
(4) And (3) transferring the mixture in the step (3) to a polytetrafluoroethylene reaction kettle with a stainless steel jacket, carrying out heat treatment for 16h at 180 ℃ to obtain a compound with dark-colored precipitates, washing the precipitates for 3 times respectively by using deionized water and absolute ethyl alcohol, and carrying out vacuum drying for 24h at 120 ℃. And then heating the dried product to 600 ℃ at the speed of 15 ℃/min in the nitrogen atmosphere, preserving the heat for 6 hours, cooling to room temperature, taking out and grinding to obtain the composite photocatalyst.
Example 2
This example provides a C-QDs-Fe2O3/TiO2The preparation method of the composite photocatalyst comprises the following steps:
(1) dispersing 4g starch in 20ml absolute ethyl alcohol, adding 5g glucose, and vigorously stirring (8000 rpm) for 10min to obtain a mixed solution.
(2) 0.1g of ferric nitrate was dissolved in 10ml of anhydrous ethanol, and the solution was added to the mixture in (1) at a rate of 2 drops/sec. Then, 8ml of acetone was added to the above solution and stirred for 50min at 8000 rpm to obtain a mixed solution.
(3) Preparing a titanium solution containing 4mL of ethylene glycol, 8mL of tetrabutyl titanate and 18mL of absolute ethyl alcohol, adding the titanium solution into the mixed solution in the step (2), and then adding 6mL of deionized water and 12mL of absolute ethyl alcohol at the speed of 2 drops per second while stirring to obtain a mixed solution.
(4) And (3) transferring the mixture in the step (3) to a polytetrafluoroethylene reaction kettle with a stainless steel jacket, carrying out heat treatment for 16h at 180 ℃ to obtain a compound with dark-colored precipitates, washing the precipitates for 3 times respectively by using deionized water and absolute ethyl alcohol, and carrying out vacuum drying for 24h at 120 ℃. And then heating the dried product to 600 ℃ at the speed of 15 ℃/min in the nitrogen atmosphere, preserving the heat for 6 hours, cooling to room temperature, taking out and grinding to obtain the composite photocatalyst.
Example 3
This example provides a C-QDs-Fe2O3/TiO2The composite photocatalyst is different from the composite photocatalyst in example 1 in that:
the step (4) is as follows: and (3) transferring the mixture in the step (3) to a polytetrafluoroethylene reaction kettle with a stainless steel jacket, heating to 80 ℃, carrying out heat treatment for 4h, then heating to 180 ℃, carrying out heat treatment for 12h to obtain a compound with dark-colored precipitates, washing the precipitates for 3 times respectively by using deionized water and absolute ethyl alcohol, and then carrying out vacuum drying for 24h at 120 ℃. And then heating the dried product to 600 ℃ at the speed of 15 ℃/min in the nitrogen atmosphere, preserving the heat for 6 hours, cooling to room temperature, taking out and grinding to obtain the composite photocatalyst.
Example 4
This example provides a C-QDs-Fe2O3/TiO2The composite photocatalyst is different from the composite photocatalyst in example 1 in that:
the step (4) is as follows: and (3) transferring the mixture in the step (3) to a polytetrafluoroethylene reaction kettle with a stainless steel jacket, heating to 80 ℃, carrying out heat treatment for 4h, then heating to 180 ℃, carrying out heat treatment for 12h to obtain a compound with dark-colored precipitates, washing the precipitates for 3 times respectively by using deionized water and absolute ethyl alcohol, and then carrying out vacuum drying for 24h at 120 ℃. Then, the dried product is heated to 300 ℃ at the speed of 15 ℃/min and is kept for 1.5h under the nitrogen atmosphere, and then is heated to 600 ℃ at the speed of 5 ℃/min and is kept for 6 h. And cooling to room temperature, taking out and grinding to obtain the composite photocatalyst.
Comparative example 1
The comparative example provides Fe2O3/TiO2The preparation method of the composite photocatalyst comprises the following steps:
(1) 0.2g of ferric nitrate was dissolved in 10ml of absolute ethanol, and then 8ml of acetone was added to the above solution, and stirred for 50min to obtain a mixed solution at a stirring speed of 8000 rpm.
(2) Preparing a titanium solution containing 4mL of ethylene glycol, 8mL of tetrabutyl titanate and 18mL of absolute ethyl alcohol, adding the titanium solution into the mixed solution in the step (1), and then adding 6mL of deionized water and 12mL of absolute ethyl alcohol at the speed of 2 drops per second while stirring to obtain a mixed solution.
(3) And (3) transferring the mixture in the step (2) to a polytetrafluoroethylene reaction kettle with a stainless steel jacket, carrying out heat treatment for 16h at 180 ℃ to obtain a compound with dark-colored precipitates, washing the precipitates for 3 times respectively by using deionized water and absolute ethyl alcohol, and carrying out vacuum drying for 24h at 120 ℃. And then heating the dried product to 600 ℃ at the speed of 15 ℃/min in the nitrogen atmosphere, preserving the heat for 6 hours, cooling to room temperature, taking out and grinding to obtain the composite photocatalyst.
Test example 1
The photocatalytic activities of the composite photocatalysts provided in examples 1 to 4 and comparative example 1 were measured, respectively.
Measuring 50ml of methyl orange solution with the concentration of 10mg/l as reaction liquid, simulating a water purification process, adding 20mg of composite photocatalyst into a 300W xenon lamp as a light source, starting magnetic stirring after the light source is 15cm away from the liquid surface, fully stirring the suspension in a dark room for 30min, starting the light source, sampling at regular intervals, and measuring the absorbance value of the supernatant.
The measurement results are shown in table 1.
TABLE 1 photocatalytic activity measurement results Table
The embodiments described above are some, but not all embodiments of the invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.