Disclosure of Invention
In order to solve the defects of the prior art, the invention aims to provide a defect type sulfur-indium-zinc microsphere visible light catalyst, a preparation method and an application thereof, which can widen the light absorption range of the catalyst, and improve the separation efficiency of photo-generated electron and hole pairs so as to improve the photocatalytic efficiency.
In order to achieve the purpose, the technical scheme of the invention is as follows:
on one hand, a preparation method of a defect type sulfur indium zinc microsphere visible light catalyst, ZnIn is prepared 2 S 4 And heating the microspheres to 90-120 ℃ in a hydrogen atmosphere for heat treatment to obtain the defective S-in-Zn microsphere visible light catalyst.
Experiments show that when hydrogen is adopted to react on ZnIn at 90-120 DEG C 2 S 4 After the microspheres are subjected to heat treatment, ZnIn is obtained 2 S 4 The specific surface area of the microspheres becomes large to increase the active sites on the surface, thereby increasing the hydrogen generation performance, and when hydrogen is treated at 80 ℃, ZnIn 2 S 4 The specific surface area of the microspheres becomes smaller, the hydrogen production performance is reduced, and ZnIn is caused when the hydrogen is treated at the temperature of more than 120 DEG C 2 S 4 The microspheres decomposed, and thus ZnIn could not be obtained 2 S 4 And (3) microspheres.
On the other hand, the defect type sulfur indium zinc microsphere visible light catalyst is obtained by the preparation method.
In a third aspect, the defect type sulfur indium zinc microsphere visible light catalyst is applied to photolysis of water to produce hydrogen.
In a fourth aspect, a method for preparing hydrogen by photolysis of water is to add the above-mentioned deficient type sulfur indium zinc microspheres to a system containing water, lactic acid and chloroplatinic acid, and perform light irradiation treatment.
The beneficial effects of the invention are as follows:
the defect ZnIn prepared by low-temperature surface hydrogenation 2 S 4 The microsphere visible-light-driven photocatalyst has good hydrogen production performance, while ZnIn prepared by the prior art 2 S 4 The photocatalyst has poor hydrogen production performance, can be improved by more than 2 times, and still has good stability through repeated tests. The catalyst with the microsphere structure has larger specific surface area and abundant surface active sites, generally shows better photocatalytic performance than bulk phase materials, and can generate surface defects after hydrogenation. In addition, the structure increases the contact area with the catalyst and greatly improves the hydrogen production performance.
The invention particularly adopts the hydrothermal and low-temperature surface hydrogenation strategies to prepare ZnIn 2 S 4 The microsphere photocatalyst can better regulate and control the surface defects of the microsphere photocatalyst. Defective ZnIn prepared by the same 2 S 4 The microsphere photocatalyst has the advantages of good stability and high photocatalytic activity, and can be applied to the fields of energy, environmental protection and the like. The invention has the advantages of simple preparation process, simple experimental equipment, low cost, high benefit and easy realization of commercialization.
Detailed Description
It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
In view of the prior ZnIn 2 S 4 The invention provides a defect of low hydrogen production efficiency, and provides a defect type sulfur indium zinc microsphere visible light catalyst, a preparation method and an application thereof.
The invention provides a preparation method of a defect type sulfur indium zinc microsphere visible light catalyst, which is implemented by mixing ZnIn 2 S 4 And heating the microspheres to 90-120 ℃ in a hydrogen atmosphere for heat treatment to obtain the defective S-in-Zn microsphere visible light catalyst.
Experiments show that when hydrogen is adopted to react with ZnIn at 90-120 DEG C 2 S 4 After the microspheres are treated, ZnIn is obtained 2 S 4 The specific surface area of the microspheres is enlarged, so that the active sites on the surface are increased, and the hydrogen production performance is improved, while ZnIn is treated at the temperature of 80 DEG C 2 S 4 The specific surface area of the microspheres becomes smaller, the hydrogen production performance is reduced, and ZnIn is caused when the hydrogen is treated at the temperature of more than 120 DEG C 2 S 4 The microspheres are decomposed, and thus ZnIn cannot be obtained 2 S 4 And (3) microspheres.
In some examples of this embodiment, the heat treatment temperature is 99 to 101 ℃. Experiments prove that the hydrogen has better treatment effect on the sulfur indium zinc microspheres at the treatment temperature, larger specific surface area and stronger hydrogen production performance.
In some examples of this embodiment, the heat treatment time is 3 to 4 hours. The heat treatment time can ensure the treatment effect of the hydrogen on the sulfur indium zinc microspheres.
In some examples of this embodiment, the heating rate of the heat treatment is 1 to 2 ℃/min.
In some embodiments of this embodiment, ZnIn 2 S 4 The preparation method of the microsphere comprises the following steps: synthesizing zinc salt, indium salt and L-cysteine by a hydrothermal method.
The hydrothermal method is a chemical reaction which is carried out in a sealed pressure container by taking water as a solvent under the conditions of high temperature (100-370 ℃) and high pressure (the environmental pressure is 21.7 MPa).
The zinc salt in the present invention refers to a compound which is soluble in water and has zinc ion as a cation, such as zinc nitrate.
The indium salt according to the present invention is a compound which is soluble in water and has an indium ion as a cation, and for example, indium nitrate and the like.
In one or more embodiments, the mass ratio of the total mass of the zinc salt, the indium salt and the L-cysteine to the mass of the water is 3-5: 5-10.
In one or more embodiments, the hydrothermal process is carried out at a temperature of 180 to 200 ℃.
In one or more embodiments, the hydrothermal treatment time is 16-20 hours.
In one or more embodiments, the hydrothermally treated material is washed with water and ethanol in sequence.
In another embodiment of the invention, the defect type sulfur indium zinc microsphere visible light catalyst is obtained by the preparation method.
The third embodiment of the invention provides an application of the defective S-in-Zn microsphere visible-light-induced photocatalyst in hydrogen production by photolysis of water.
In a fourth embodiment of the present invention, there is provided a method for preparing hydrogen by photolyzing water, wherein the defective S-in-Zn microspheres are added to a system containing water, lactic acid and chloroplatinic acid, and then subjected to light irradiation.
In some examples of the embodiment, the light irradiation treatment is performed by using a 200-400W xenon lamp and a power density of 50-150 mW cm -2 Irradiating for 4-6 hours under the condition of simulating sunlight.
In order to make the technical solutions of the present invention more clearly understood by those skilled in the art, the technical solutions of the present invention will be described in detail below with reference to specific embodiments.
Example 1
0.074g of Zn (NO) is weighed out 3 ) 2 ·6H 2 O and 0.15g In (NO) 3 ) 3 ·H 2 O stirring (rotating speed 500r min) -1 ) Dissolved in 30mL of distilled water, and further added with 0.233g L-cysteine to continue stirring for 2 hours. The hydrothermal reaction was carried out at 200 ℃ for 18 h. After cooling, the solution was centrifuged (4000r min) -1 And centrifuged for 3min), and the separated precipitate was washed three times with water and ethanol, respectively. Vacuum drying at 60 deg.C for 12h in drying oven, and grinding the dried powder to obtain ZnIn 2 S 4 And (3) powder materials. ZnIn is mixed with a solvent 2 S 4 Placing the powder material in a tubular furnace, introducing hydrogen into the tubular furnace, wherein the flow rate of the hydrogen is 40mL min -1 Heating to 80 ℃ at the speed of 2 ℃/min, roasting for 3h, and cooling to room temperature to obtain the defective ZnIn 2 S 4 And (3) powder materials.
Example 2
0.074g of Zn (NO) is weighed out 3 ) 2 ·6H 2 O and 0.15g In (NO) 3 ) 3 ·H 2 O stirring (rotating speed 500r min) -1 ) Dissolved in 30mL of distilled water, and further added with 0.233g L-cysteine to continue stirring for 2 hours. The hydrothermal reaction was carried out at 200 ℃ for 18 h. After cooling, the solution was centrifuged (4000r min) -1 And centrifuged for 3min), and the separated precipitate was washed three times with water and ethanol, respectively. Vacuum drying at 60 deg.C for 12h in drying oven, and grinding the dried powder to obtain ZnIn 2 S 4 And (3) powder materials. ZnIn is reacted with a catalyst to form a catalyst 2 S 4 Placing the powder material in a tubular furnace, introducing hydrogen into the tubular furnace, wherein the flow of the hydrogen is 40mL min -1 Heating to 100 deg.C at a rate of 2 deg.C/min, calcining for 3 hr, and coolingCooling to room temperature to obtain defective ZnIn 2 S 4 And (3) powder materials.
Example 3
0.074g of Zn (NO) is weighed out 3 ) 2 ·6H 2 O and 0.15g In (NO) 3 ) 3 ·H 2 O stirring (rotating speed 500r min) -1 ) Dissolved in 30mL of distilled water, and further added 0.233g L-cysteine, and stirred for 2 hours. The hydrothermal reaction was carried out at 200 ℃ for 18 h. After cooling, the solution was centrifuged (4000r min) -1 And centrifuged for 3min), and the separated precipitate was washed three times with water and ethanol, respectively. Vacuum drying at 60 deg.C for 12h in drying oven, and grinding the dried powder to obtain ZnIn 2 S 4 And (3) powder materials. ZnIn is reacted with a catalyst to form a catalyst 2 S 4 Placing the powder material in a tubular furnace, introducing hydrogen into the tubular furnace, wherein the flow rate of the hydrogen is 40mL min -1 Heating to 120 ℃ at the speed of 2 ℃/min, roasting for 3h, and cooling to room temperature to obtain defective ZnIn 2 S 4 And (3) powder materials.
Examples 1 to 3 preparation of defective ZnIn 2 S 4 The experimental scheme for microspheres is shown in FIG. 1.
Examples 1 to 3 preparation of defective ZnIn 2 S 4 The XRD spectrum of the microsphere is shown in figure 2, the position of each diffraction peak is related to ZnIn 2 S 4 The major crystal planes substantially correspond. The characteristic diffraction peaks of the four samples do not change too much, the positions and peak widths are similar, and no obvious shift occurs. The width of the diffraction peak of the sulfur indium zinc is slightly increased and the intensity of the diffraction peak is slightly weakened after low-temperature hydrogenation reduction. The reason for this may be that the structure of the material crystals is slightly changed during the hydrogen calcination. The sample can keep the original structure after low-temperature hydrogenation reduction treatment, and has good stability.
Examples 1 to 3 preparation of defective ZnIn 2 S 4 The nitrogen adsorption-desorption curves and pore size distribution curves of the microspheres are shown in FIGS. 3-4, and the defective ZnIn prepared in examples 2 and 3 2 S 4 The microspheres are improved compared to the as-is, wherein the specific surface area is highest at 100 ℃ of the hydrotreatment. The pore sizes of these samples were mostly aggregatedAbout 10nm, and thus belongs to a mesoporous material. The larger the specific surface area of the sample, the more active sites are exposed on the surface of the sample, and the more sulfur vacancies are generated on the surface after the hydrotreating, and these sulfur vacancy defects contribute to the enhancement of the photocatalytic activity.
Example 2 defective ZnIn preparation 2 S 4 As shown in FIG. 5, the SEM image of the microspheres shows that the spherical structure is very obvious, the morphology is uniform, and the diameter of the sphere is about 5 μm. Compared with other materials, the microsphere structure can provide more active sites, and the photocatalytic oxidation capacity is greatly improved.
The defective ZnIn prepared in example 2 2 S 4 A microsphere visible-light-driven photocatalyst is used for a photocatalytic hydrogen production test, and the method comprises the following steps: to a solution containing 90mL of water, 10mL of lactic acid and 0.1mL of 0.5 wt% chloroplatinic acid, 50mg of ZnIn was added 2 S 4 And (3) irradiating the microsphere photocatalyst for 5 hours under the condition of 300W simulated sunlight, and analyzing hydrogen generated in the device by using a gas chromatograph and calculating the hydrogen yield. Through calculation, the defective ZnIn prepared in the example 2 under the condition that the hydrogenation temperature is 100 DEG C 2 S 4 The microsphere visible-light-driven photocatalyst has good hydrogen production performance (2.15mmol h) -1 g -1 ) Is improved by more than 2 times (0.99mmol h) than the performance before hydrogenation -1 g -1 ) And has good stability through a cycle test. Due to the microsphere structure, the contact area of the microsphere structure and a catalyst is increased, and the photocatalytic hydrogen production performance is improved.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.