Preparation method of bismuth oxyhalide photocatalytic material and application thereof
By preparing a Bi-BiOI-Bi5O7I three-phase composite bismuth halide photocatalyst, the problems of complex production process and poor photocatalytic effect of existing bismuth halide photocatalysts were solved, achieving efficient removal of NO and inhibition of NO2 generation, thus improving photocatalytic performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHONGQING COLLEGE OF ELECTRONICS ENG
- Filing Date
- 2023-12-18
- Publication Date
- 2026-06-05
Smart Images
Figure CN117680169B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of photocatalyst technology, specifically relating to a method for preparing bismuth halide photocatalyst materials and their applications. Background Technology
[0002] In recent years, photocatalytic technology based on semiconductor photocatalytic materials to degrade pollutants in water using sunlight has developed rapidly. The earliest photocatalytic material, TiO2, has a wide band gap, resulting in low utilization of sunlight; and its photocatalytic efficiency is very low due to the easy recombination of electrons and holes during the catalytic process. This has led researchers to focus on developing new, highly efficient, and broad-spectrum-responsive photocatalysts.
[0003] Among numerous novel photocatalysts, bismuth-based catalysts are favored due to their unique crystal structure and high carrier separation efficiency. Bismuth oxyhalides (BiOX, X = Cl, Br, I) photocatalysts possess a layered structure with separated positive and negative charges. The presence of an electrostatic field between the layers effectively reduces the recombination of photogenerated electrons and holes, resulting in superior catalytic performance. The band gap of BiOX decreases with increasing halogen atomic number, leading to a corresponding increase in its light absorption capacity. Furthermore, BiOX offers advantages such as abundant raw material sources, low cost, and easily tunable band structure, attracting widespread attention in the photocatalytic treatment of air pollutants. However, the high recombination rate of photogenerated carriers limits the photocatalytic activity of BiOX photocatalysts, preventing them from fully meeting the demands of large-scale applications. Currently, a single charge separation pathway cannot adequately suppress the rapid recombination of electron-hole pairs, making it challenging to achieve highly efficient catalysis of target reactions through precise structural design and carrier control. Summary of the Invention
[0004] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, the main objective of this invention is to provide a method for preparing bismuth halide photocatalysts, aiming to solve the problems of complex production processes and poor photocatalytic effects in existing bismuth halide photocatalysts. This invention also provides applications of this bismuth halide photocatalyst.
[0005] The objective of this invention is achieved through the following technical solution:
[0006] In a first aspect, a method for preparing a bismuth halide photocatalytic material includes the following steps:
[0007] 1) Add bismuth nitrate pentahydrate and potassium iodide to a dispersion solvent and stir continuously at room temperature until completely dissolved to obtain a mixture;
[0008] 2) The mixture is transferred to an autoclave for hydrothermal reaction to obtain a suspension;
[0009] 3) Cool the suspension to room temperature naturally, centrifuge, take the precipitate, wash and dry it to obtain the bismuth halide photocatalytic material.
[0010] In some specific embodiments, the molar ratio of bismuth nitrate pentahydrate to potassium iodide is 1:1.
[0011] In some specific embodiments, the ratio of bismuth nitrate pentahydrate to dispersion solvent is 1:30, expressed in mmol:mL.
[0012] In some specific embodiments, the dispersing solvent is one of ethanol, propanol, ethylene glycol, and glycerol.
[0013] In some specific embodiments, the hydrothermal reaction conditions in step 2) are a hydrothermal reaction temperature of 180-200°C and a hydrothermal reaction time of 12-24 hours.
[0014] In some specific embodiments, the washing in step 3) includes washing with deionized water and ethanol in sequence, and repeating the process twice.
[0015] In some specific embodiments, the drying in step 3) is performed at a temperature of 30-50°C for 24 hours.
[0016] Secondly, a bismuth oxyhalide photocatalyst material prepared by the aforementioned method is a Bi-BiOI-Bi5O7I three-phase composite.
[0017] Thirdly, the application of the aforementioned bismuth oxide halide photocatalytic material in the photocatalytic degradation of organic compounds.
[0018] Compared with the prior art, the present invention has at least the following advantages:
[0019] The present invention provides a method for preparing bismuth halide photocatalysts. Using Bi(NO3)3·5H2O and KI as precursors and ethylene glycol as solvent, a simple one-step hydrothermal synthesis method is employed to prepare a Bi-BiOI-Bi5O7I three-phase composite bismuth halide photocatalyst. This Bi-BiOI-Bi5O7I three-phase composite exhibits excellent photocatalytic performance, with a visible light removal rate of 56.74% for NO and a 62% reduction in NO2 generation compared to BiOI. These results demonstrate that the oxygen defect / heterojunction synergy can efficiently remove NO and effectively inhibit the generation of the toxic byproduct NO2. Attached Figure Description
[0020] To more clearly illustrate the specific embodiments of the present invention, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below.
[0021] Figure 1 This is an X-ray diffraction pattern of the bismuth halide photocatalytic material in Example 2 of the present invention. Detailed Implementation
[0022] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The following embodiments are merely descriptive and not limiting, and should not be construed as limiting the scope of protection of the present invention.
[0023] When a quantity, concentration, or other value or parameter is described as a range, preferred range, or preferred upper and lower limits, it should be understood that it is equivalent to specifically disclosing any range by combining any pair of upper or preferred values with any lower or preferred values, regardless of whether the range is specifically disclosed. Unless otherwise stated, the numerical range values listed herein include the endpoints of the range and all integers and fractions within that range.
[0024] Unless otherwise stated, all percentages, parts, ratios, etc. in this document are by weight.
[0025] The materials, methods, and embodiments described herein are exemplary and should not be construed as limiting unless otherwise stated.
[0026] Example 1
[0027] The preparation method of the bismuth halide photocatalytic material provided by the present invention includes the following steps:
[0028] 1) Add 2 mmol of bismuth nitrate pentahydrate and 4 mmol of potassium iodide to 60 ml of ethylene glycol solvent, and stir continuously at room temperature for 60 min until completely dissolved to obtain a mixture;
[0029] 2) Transfer the mixture to a stainless steel autoclave lined with polytetrafluoroethylene and maintain the reaction at 180°C for 12 hours to obtain a suspension.
[0030] 3) Cool the suspension to room temperature naturally, collect the precipitate by centrifugation, wash it twice with deionized water and twice with ethanol, and then dry it in an oven at 30°C for 24 hours to obtain the bismuth halide photocatalytic material.
[0031] Example 2
[0032] The preparation method of the bismuth halide photocatalytic material provided by the present invention includes the following steps:
[0033] 1) Add 2 mmol of bismuth nitrate pentahydrate and 2 mmol of potassium iodide to 60 ml of ethylene glycol solvent, and stir continuously at room temperature for 30 min until completely dissolved to obtain a mixture;
[0034] 2) Transfer the mixture to a stainless steel autoclave lined with polytetrafluoroethylene and maintain the reaction at a reaction temperature of 190°C for 18 hours to obtain a suspension.
[0035] 3) Cool the suspension to room temperature naturally, collect the precipitate by centrifugation, wash it twice with deionized water and twice with ethanol, and then dry it in an oven at 40°C for 24 hours to obtain the bismuth halide photocatalytic material.
[0036] Example 3
[0037] The preparation method of the bismuth halide photocatalytic material provided by the present invention includes the following steps:
[0038] 1) Add 2 mmol of bismuth nitrate pentahydrate and 7 mmol of potassium iodide to 60 ml of ethylene glycol solvent, and stir continuously at room temperature for 30 min until completely dissolved to obtain a mixture;
[0039] 2) Transfer the mixture to a stainless steel autoclave lined with polytetrafluoroethylene and maintain the reaction at 200°C for 24 hours to obtain a suspension;
[0040] 3) Cool the suspension to room temperature naturally, collect the precipitate by centrifugation, wash it twice with deionized water and twice with ethanol, and then dry it in an oven at 50°C for 24 hours to obtain the bismuth halide photocatalytic material.
[0041] Taking Example 2 as an example, this application analyzes the crystal structure and phase composition of the prepared bismuth halide photocatalyst material using X-ray diffraction (XRD: Rigaku D / Max RA, Japan). Specifically, the target is a copper target, the operating voltage is 40 kV, the tube current is 30 mA, the scanning speed is 4° / min, and the scanning range is 2θ = 10-80°. The results are as follows: Figure 1 As shown in the figure, diffraction peaks corresponding to Bi (PDF#44-1246), BiOI (PDF#10-0445), and Bi5O7I (PDF#40-0548) were observed in the XRD pattern. The XRD characterization results indicate that Bi, BiOI, and Bi5O7I coexist in the Bi / BiOI / Bi5O7I sample.
[0042] In addition, this application also tests the catalytic performance of the prepared bismuth halide photocatalyst material. Taking Example 2 as an example, the bismuth halide photocatalyst material prepared in Example 2 is used for photocatalytic NO removal. Specifically, the NO removal test is conducted in a continuous flow reactor: a 150W commercial xenon lamp is used for visible light-driven photocatalytic removal of NO. The lamp is equipped with a UV filter (420nm) to block UV light. The continuous flow reactor is rectangular with a volume of 4.5L (30cm x 15cm x 10cm). The initial NO concentration is approximately 500 ppb. Before the reaction, 0.20 g of the bismuth halide photocatalyst material (prepared by the method in Example 2) is coated onto two glass dishes (12.0 cm in diameter) and placed in the reactor. Adsorption-desorption equilibrium is reached under dark conditions. During the reaction, the NO concentration is continuously measured using a NOx analyzer (Thermoelectric, model 42i-TL), and the NOx concentration (NOx represents both NO and NO2) is analyzed simultaneously. The NO removal rate is defined as η(%) = (1-C / C0) × 100%, where C and C0 are the NO concentrations in the effluent and feed streams, respectively.
[0043] The bismuth halide photocatalyst material prepared in Example 2 was applied to the purification of a typical air pollutant, NO (approximately 500 ppb). The results after 30 minutes of reaction showed that the bismuth halide photocatalyst material (Bi-BiOI-Bi5O7I three-phase composite) provided in this application achieved a visible light removal rate of 56.74% for NO, and the NO2 generation was reduced by 62% compared to BiOI. This result indicates that the oxygen defect / heterojunction synergy can efficiently remove NO and effectively inhibit the generation of the toxic byproduct NO2.
[0044] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.
Claims
1. The application of a bismuth halide photocatalytic material in the photocatalytic removal of NO, characterized in that, The bismuth oxide halide photocatalyst material is obtained by the following preparation method, with the specific steps as follows: 1) Add bismuth nitrate pentahydrate and potassium iodide to a dispersion solvent and stir continuously at room temperature until completely dissolved to obtain a mixture; 2) The mixture is transferred to an autoclave for hydrothermal reaction to obtain a suspension; 3) Cool the suspension to room temperature naturally, centrifuge, take the precipitate, wash and dry it to obtain the bismuth halide photocatalyst material; the bismuth halide photocatalyst material is a Bi-BiOI-Bi5O7I three-phase composite. In step 1), the molar ratio of bismuth nitrate pentahydrate to potassium iodide is 1-4:1; the ratio of bismuth nitrate pentahydrate to dispersing solvent is 1:30 (mmol:mL); the dispersing solvent is one of ethanol, propanol, ethylene glycol, and glycerol; the hydrothermal reaction conditions in step 2) are a hydrothermal reaction temperature of 180-200℃ and a hydrothermal reaction time of 12-24h; and the drying in step 3) is a drying treatment at 30-50℃ for 24h.
2. The application according to claim 1, characterized in that, The washing process described in step 3) includes washing with deionized water and ethanol in sequence, and repeating the process twice.