Near-infrared light responsive Ag2S-Bi4NbO8Preparation method of Cl composite photocatalyst
阅读说明：本技术 一种近红外光响应的Ag2S-Bi4NbO8Cl复合光催化剂的制备方法 (Near-infrared light responsive Ag2S-Bi4NbO8Preparation method of Cl composite photocatalyst ) 是由 石良 吴锡录 尹正茂 曲晓飞 杜芳林 于 2020-10-22 设计创作，主要内容包括：光催化技术已被广泛用作一种经济有效且环保的高级氧化过程,广泛用于环境污水处理环节中。具有Aurivilius-Sillén结构的Bi-4NbO-8Cl材料作为一种新型的铋基氯氧化物光催化剂,其独特的层状分子结构有利于光生载流子的分离,拥有良好的光催化性能。然而由于Bi-4NbO-8Cl的禁带宽度仍达到约2.5eV,使其只能对波长约为500nm以下的蓝紫可见光区域响应。本发明采用熔盐法制备的Bi-4NbO-8Cl为基体,利用化学沉淀法制备了Ag-2S负载的Bi-4NbO-8Cl复合光催化材料,拓展了Bi-4NbO-8Cl材料的光响应范围,同时Ag-2S-Bi-4NbO-8Cl异质结构的构建加强了光生电荷的分离,提高了光催化降解医疗废水的效率。(Photocatalytic technology has been widely used as an economical, efficient and environmentally friendly advanced oxidation process, widely used in environmental sewage treatment processes. Bi having Aurivillius-Sillen structure 4 NbO 8 The Cl material is used as a novel bismuth-based oxychloride photocatalyst, the unique layered molecular structure of the Cl material is beneficial to the separation of photon-generated carriers, and the Cl material has good photocatalytic performance. However, since Bi 4 NbO 8 The forbidden band width of Cl still reaches about 2.5eV, so that it can only respond to the blue-violet visible light region with the wavelength below about 500 nm. The invention adopts Bi prepared by a molten salt method 4 NbO 8 Using Cl as matrix and preparing Ag by chemical precipitation method 2 S-loaded Bi 4 NbO 8 The Cl composite photocatalytic material expands Bi 4 NbO 8 Photoresponse range of Cl material with Ag 2 S‑Bi 4 NbO 8 The construction of the Cl heterostructure strengthens the separation of photo-generated charges and improves the efficiency of photocatalytic degradation of medical wastewater.)
1. Near-infrared light responsive Ag2S-Bi4NbO8The preparation method of the Cl composite photocatalyst is characterized by comprising the following steps:
(1)Bi4NbO8preparing Cl powder: respectively weighing NaCl and KCl with the amount of 0.1mol at room temperature, and placing in an agate mortar(ii) a Then 0.01mol of BiOCl and 0.005mol of Nb are weighed in sequence2O5And 0.015mol of Bi2O3Sequentially adding the mixture into an agate mortar; grinding the mixture in an agate mortar for 15min until no obvious granular sensation exists; further transferring the mixture into an agate ball milling tank, simultaneously adding 10mm agate balls, sealing the ball milling tank, and placing the ball milling tank in a planetary ball mill for ball milling for 2 hours at the rotating speed of 300 rpm; transferring the powder subjected to ball milling into a corundum crucible, calcining in a 600-plus-800 ℃ muffle furnace, keeping the temperature for 0.5-5h, and keeping the temperature rise rate at 2-5 ℃/min; taking out the calcined product, washing the calcined product without grinding by using 300mL of hot water with the temperature of 80 ℃ for 5 times, and paying attention to ultrasonic treatment in the process; with 0.1mol/L AgNO3Examination of residual Cl-Concentration; drying the product in an oven at 60 ℃ for 12h, and grinding to obtain Bi4NbO8Cl powder;
(2) preparing a silver-ammonia complex solution: taking 5mmol of AgNO3Dissolving in 50mL of deionized water, and dropwise adding a diluted ammonia water solution with a certain volume concentration into the AgNO3Shaking the solution until the precipitate generated initially just dissolves and disappears; the silver-ammonia complex solution is metered to be 100 mL;
(3) weighing the substance in an amount of 0.5mmol of Bi prepared in the step (1)4NbO8Dispersing Cl powder into 50mL of deionized water, and performing ultrasonic treatment for 10min to uniformly disperse the Cl powder; dropwise adding a certain amount of prepared silver ammonia solution into the suspension, and continuously stirring for 30 min; adding a certain amount of Na with the concentration of 0.02mmol/L2Dropwise adding the solution of the S into the suspension, and stirring for 3 hours in a dark place;
(4) centrifuging the suspension in the step (3) at 10000rpm, collecting precipitates, and washing the precipitates respectively for 3 times by using deionized water and ethanol in sequence; drying the collected precipitate in a blast drying oven at 60 deg.C for 24 hr, and collecting powder to obtain Ag2S-Bi4NbO8Cl。
2. The near-infrared light-responsive Ag of claim 12S-Bi4NbO8The preparation method of the Cl composite photocatalyst is characterized by comprising the following steps2) The volume concentration of the medium and weak ammonia water is 1-5%.
3. The near-infrared light-responsive Ag of claim 12S-Bi4NbO8The preparation method of the Cl composite photocatalyst is characterized in that the adding amount of the silver-ammonia solution in the step (3) is 0.2mL-4.0 mL.
4. The near-infrared light-responsive Ag of claim 12S-Bi4NbO8The preparation method of the Cl composite photocatalyst is characterized in that Na is added in the step (3)2The S solution is added in an amount of 0.25mL-5.0mL and Na2The volume ratio of the S solution to the silver ammonia solution was always maintained at 1.25 to 1.
The technical field is as follows:
the invention relates to near infrared light responsive Ag2S-Bi4NbO8Preparation method of Cl composite photocatalyst, specifically, preparation of Bi by molten salt method4NbO8The Cl lamellar structure is taken as a substrate, and Ag is constructed by utilizing a silver-ammonia complex+-Bi4NbO8Strong interaction between Cl, preparing Ag by chemical precipitation method2S nanoparticles by control of Ag2S different in loading amount, expands the photoresponse range of the photocatalyst and improves the efficiency of photocatalytic degradation of medical wastewater, and the technology belongs to the field of preparation of photocatalytic materials.
Background art:
with the aging process of the world population and the rapid growth of the medical industry, the pollution of medical wastewater to the environment has become a serious problem. The medical wastewater contains not only highly pathogenic and highly infectious virus and germs, but also more antibiotic substances discharged by human body. Therefore, the strict treatment of the residual antibiotics in the medical wastewater has important significance for protecting the ecological environment and the human health.
Photocatalytic technology has been widely used as an economically efficient and environmentally friendly advanced oxidation process to remove harmful environmental pollutants. Conventional semiconductor catalysts such as TiO2ZnO, etc., which respond only to uv light in the region of 5% of the solar spectrum and do not respond to visible and near-infrared light in the region of 49% and 46%, respectively. Therefore, expanding the spectral response range of the photocatalyst becomes a challenging issue.
Recent studies have found that Bi has an Aurivillius-Sillen structure4NbO8The Cl material as a novel bismuth-based oxychloride photocatalyst consists of [ Bi2O2]2+Layer, [ NbO ]4]3-Layer and [ Cl]-The unique layered molecular structure is beneficial to the separation of photon-generated carriers, thereby improving the photocatalytic performance of the catalyst. Since Bi4NbO8The valence band and the conduction band of Cl have strong Bi 6s orbital and O2 p orbital hybridization, and the characteristic can reduce the band gap and provide visible lightAbsorption and higher light stability. However, its forbidden band width of about 2.5eV only enables the photocatalytic material to respond to the blue-violet visible region below about 500 nm. Thus, further by reacting Bi4NbO8It is imperative that Cl materials be modified to improve the photoresponse range.
Silver sulfide (Ag)2S) has an extremely small optical band gap (0.9eV), and has good response performance to near infrared light. However, due to the very specific band gap and structure, Ag2S has a fast photo-generated charge recombination rate and a weak oxidation-reduction potential, and is difficult to be used as a photocatalyst alone. Therefore, we designed an Ag2S-loaded Bi4NbO8Preparation method of Cl composite photocatalyst, Ag2S expands the photoresponse range of the photocatalyst, and Ag simultaneously2S-Bi4NbO8The construction of the Cl heterostructure strengthens the separation of photo-generated charges and improves the efficiency of photocatalytic degradation of medical wastewater.
The invention content is as follows:
the invention adopts a chemical precipitation method to prepare the Ag with excellent performance2S-Bi4NbO8Cl combined with visible light catalyst.
The invention is realized by the following technical scheme:
near-infrared light responsive Ag2S-Bi4NbO8The preparation method of the Cl composite photocatalyst comprises the following steps:
(1)Bi4NbO8preparing Cl powder: respectively weighing NaCl and KCl with the amount of 0.1mol at room temperature, and putting into an agate mortar; then 0.01mol of BiOCl and 0.005mol of Nb are weighed in sequence2O5And 0.015mol of Bi2O3Sequentially adding the mixture into an agate mortar; grinding the mixture in an agate mortar for 15min until no obvious granular sensation exists; further transferring the mixture into an agate ball milling tank, simultaneously adding 10mm agate balls, sealing the ball milling tank, and placing the ball milling tank in a planetary ball mill for ball milling for 2 hours at the rotating speed of 300 rpm; transferring the powder after ball milling into a corundum crucible, calcining for a certain time in a muffle furnace, and keeping for a certain timeThe rate of temperature rise; taking out the calcined product, washing the calcined product without grinding by using 300mL of hot water with the temperature of 80 ℃ for 5 times, and paying attention to ultrasonic treatment in the process; with 0.1mol/L AgNO3Examination of residual Cl-Concentration; drying the product in an oven at 60 ℃ for 12h, and grinding to obtain Bi4NbO8Cl powder;
(2) preparing a silver-ammonia complex solution: taking 5mmol of AgNO3Dissolving in 50mL of deionized water, and dropwise adding a diluted ammonia water solution with a certain volume concentration into the AgNO3Shaking the solution until the precipitate generated initially just dissolves and disappears; the silver-ammonia complex solution is metered to be 100 mL;
(3) weighing the substance in an amount of 0.5mmol of Bi prepared in the step (1)4NbO8Dispersing Cl powder into 50mL of deionized water, and performing ultrasonic treatment for 10min to uniformly disperse the Cl powder; dropwise adding a certain amount of prepared silver ammonia solution into the suspension, and continuously stirring for 30 min; adding a certain amount of Na with the concentration of 0.02mmol/L2Dropwise adding the solution of the S into the suspension, and stirring for 3 hours in a dark place; wherein the addition amount of the silver ammonia solution is 0.2mL-4.0mL, and Na2The addition amount of the S solution is 0.25mL-5.0mL according to the ratio of n (S) to n (Ag) to 1: 2;
(4) centrifuging the suspension in the step (3) at 10000rpm, collecting precipitates, and washing the precipitates respectively for 3 times by using deionized water and ethanol in sequence; drying the collected precipitate in a blast drying oven at 60 deg.C for 24 hr, and collecting powder to obtain Ag2S-Bi4NbO8Cl。
Preferably, the calcination temperature in the step (1) is 600-.
Preferably, the volume concentration of the dilute ammonia water in the step (2) is 1-5%.
Preferably, the silver ammonia solution added in the step (3) is in the amount (V)Ag) 0.2mL-4.0mL, the amount of sodium sulfide added (V)S) Is 0.25mL-5.0mL and always maintains VAg：VS＝1：1.25。
Compared with the prior art, the invention has the beneficial effects that:
in the inventionBi prepared by molten salt method4NbO8The Cl sheet structure is taken as a substrate, and silver-ammonia complex ions and Bi are utilized4NbO8Strong interaction between Cl, preparing Ag by chemical precipitation method2S nanoparticles, preparation of Ag2S-Bi4NbO8The Cl composite photocatalytic material expands the photoresponse range and photocatalytic activity of the photocatalytic material. The invention uses Bi4NbO8Based on a photocatalyst with Cl visible light response, the photocatalyst is loaded with infrared light with narrow band gap Ag2S semiconductor nano-particles and the proportion of the nano-particles in the compound are regulated and controlled to obtain the Ag responsive to infrared light2S-Bi4NbO8The Cl composite photocatalyst is used in the field of photocatalytic degradation of medical wastewater, achieves good effect, and can be used as a V catalystAg2.0mL and VSWhen the total volume is 2.5mL, Ag2S-Bi4NbO8The Cl has optimal photocatalytic degradation efficiency on the target pollutant tetracycline hydrochloride.
Description of the drawings:
FIG. 1 shows Ag prepared in different proportions according to the present invention2S-loaded Bi4NbO8XRD pattern of the Cl composite photocatalyst.
Fig. 2 is an SEM image of the sample prepared in example 1.
FIG. 3 shows Ag prepared in different proportions according to the present invention2S-loaded Bi4NbO8DRS diagram of Cl composite photocatalyst.
FIG. 4 is a graph showing the degradation curve of the composite photocatalyst and the matrix prepared in example 1 to tetracycline hydrochloride under the irradiation of near infrared light.
The specific implementation mode is as follows:
example 1:
respectively weighing NaCl and KCl with the amount of 0.1mol at room temperature, and putting into an agate mortar; then 0.01mol of BiOCl and 0.005mol of Nb are weighed in sequence2O5And 0.015mol of Bi2O3Sequentially adding the mixture into an agate mortar; grinding the mixture in an agate mortar for 15min until no obvious granular sensation exists; further transferring the mixture into an agate ball milling tank, simultaneously adding 10mm agate balls, sealing the ball milling tank, and placing the ball milling tank in a planetary ball milling wayBall milling is carried out in the machine for 2 hours, and the rotating speed is 300 rpm; transferring the powder subjected to ball milling into a corundum crucible, calcining for 1h at 750 ℃ in a muffle furnace, and keeping the heating rate at 3 ℃/min; taking out the calcined product, washing the calcined product without grinding by using 300mL of hot water with the temperature of 80 ℃ for 5 times, and paying attention to ultrasonic treatment in the process; with 0.1M AgNO3Examination of residual Cl-Concentration; drying the product in an oven at 60 ℃ for 12h, and grinding to obtain Bi4NbO8And (3) Cl powder.
Weighing Bi with the amount of 0.5mmol4NbO8Dispersing Cl powder into 50mL of deionized water, and performing ultrasonic treatment for 10min to uniformly disperse the Cl powder; dropwise adding 2.0mL of 0.05mol/L silver ammonia solution prepared in advance into the suspension, and continuously stirring for 30 min; 2.5mL of Na with a concentration of 0.02mmol/L2Dropwise adding the solution of the S into the suspension, and stirring for 3 hours in a dark place; centrifuging the suspension at 10000rpm, collecting the precipitate, and sequentially washing the precipitate for 3 times by using deionized water and ethanol respectively; drying the collected precipitate in a blast drying oven at 60 deg.C for 24 hr, and collecting powder to obtain Ag2S-Bi4NbO8And (4) Cl. Ag produced according to theoretical calculation2S and Bi4NbO8The mass ratio of Cl was 0.10:1 and the sample was labeled AB-10.
Example 2:
the present embodiment is different from embodiment 1 in that:
the volume of the added silver ammonia solution is 0.4mL, and Na is added2The volume of the solution of S was 0.5 mL. Ag finally obtained2S-Bi4NbO8Ag in Cl2S and Bi4NbO8The mass ratio of Cl was 0.02:1, so the sample obtained in this example was labeled AB-2.