Preparation method and application of a two-dimensional nano-titanium carbide / cobalt octasulfide nonasulfide heterojunction photocatalytic material

Abstract

A preparation method and application of a two-dimensional nano-titanium carbide / nonacobalt octasulfide heterojunction photocatalytic material. This invention aims to address the problem that, during the H2O2 production process, existing photocatalysts primarily absorb light in the red and near-infrared regions of visible light, resulting in low photogenerated carrier separation efficiency. The preparation method includes the following steps: 1. Sequentially add CH3CSNH2 and NaOH to a cobalt nitrate solution and stir at room temperature to obtain a Co9S8 matrix; 2. Add titanium aluminum carbide to a hydrofluoric acid solution and react for a long period of time to obtain a precursor Ti3C2 powder. This precursor Ti3C2 powder is then dispersed in a dimethyl sulfoxide solution and stirred to obtain Ti3C2 powder; 3. Prepare the Ti3C2 / Co9S8 heterojunction photocatalytic material. The Ti3C2 / Co9S8 heterojunction photocatalytic material prepared by this invention can expand the visible light absorption range and exhibit excellent photocatalytic H2O2 production activity.

Description

Technical Field

[0001] The invention relates to a preparation method and application of a Ti3C2 / Co9S8 heterojunction photocatalytic material. Background Art

[0002] In recent years, in-depth research has been conducted both domestically and internationally on the scientific and technological challenges of photocatalytic H2O production, including improving photocatalytic efficiency, optimizing solar energy utilization and visible light response range, and improving photocatalytic reaction systems. These breakthroughs have brought hope for the full application of solar energy in a wider range of fields. The photocatalytic production of H2O2 from H2O using semiconductor materials as photocatalysts and sunlight or visible light as the driving force (hereinafter referred to as "photo-H2O2") boasts mild reaction conditions and can directly utilize sunlight as an energy source for chemical reactions. Its potential for application in the field of H2O2 synthesis is gradually emerging. This process, which uses raw materials derived from nature, is environmentally friendly, safe, and energy-efficient, and is highly suitable for producing low-concentration H2O2 required for the oxidation of small molecules. Consequently, the search for more efficient semiconductor-based photocatalytic materials, coupled with functionalization of other active components to achieve "bifunctional" or "integrated" effects, has attracted increasing attention, ultimately demonstrating the atom economy of photo-H2O2 production technology.

[0003] MXenes, a novel two-dimensional material, possess a broad absorption range in both the visible and near-infrared regions. Absorbed incident light is converted into heat, raising the system temperature and accelerating the thermodynamics and kinetics of electron transfer, thereby increasing macroscopic reaction rates. Ti3C2, a classic MXenes material, possesses a two-dimensional layered structure, excellent conductivity, and robust visible light responsiveness. Its chemical, electronic, and surface activity can be manipulated through surface modification and ion exchange to meet the needs of diverse applications. Summary of the Invention

[0004] The present invention aims to solve the problems that in the process of photocatalytic preparation of H2O2 by existing photocatalysts, the absorption range is mainly concentrated in the red and near-infrared light regions of visible light, while the absorption ability for other wavelengths in the visible spectrum range is weak, and the efficiency of photogenerated carrier separation is low. A preparation method and application of Ti3C2 / Co9S8 heterojunction photocatalytic material are provided.

[0005] The preparation method of the Ti3C2 / Co9S8 heterojunction photocatalytic material of the present invention is achieved by the following steps:

[0006] 1. Preparation of Co9S8 matrix:

[0007] Co(NO3)2·6H2O was dissolved in deionized water and stirred to obtain a cobalt nitrate solution. CH3CSNH2 and NaOH were then added to the cobalt nitrate solution in sequence and stirred at room temperature for 1.5 to 3 hours. The solid phase product was washed with water and dried to obtain a Co9S8(CS) matrix.

[0008] 2. Preparation of Ti3C2:

[0009] a. Add titanium aluminum carbide (Ti3AlC2) to a 40 wt.% hydrofluoric acid solution and stir the mixture at room temperature for 45 to 60 hours. Wash and dry the solid phase to obtain a Ti3C2 precursor powder.

[0010] b. Dispersing the precursor Ti3C2 powder in dimethyl sulfoxide (DMSO) solution, stirring for 20 to 30 hours, then ultrasonically treating for 1 to 2 hours, washing and drying to obtain Ti3C2 powder;

[0011] 3. Preparation of Ti3C2 / Co9S8 heterojunction photocatalytic materials:

[0012] The Co9S8 matrix and Ti3C2 powder are mixed and ground to obtain a mixed powder, which is then dispersed in DMSO and stirred at room temperature for 20 to 30 hours, followed by ultrasonic treatment for 1 to 2 hours. The reaction product is washed and dried to obtain a Ti3C2 / Co9S8 heterojunction photocatalytic material.

[0013] The application of the Ti3C2 / Co9S8 heterojunction photocatalytic material of the present invention is to use the Ti3C2 / Co9S8 heterojunction photocatalytic material to photocatalyze H2O to prepare H2O2.

[0014] Compared with the prior art, the preparation method and application of the Ti3C2 / Co9S8 heterojunction photocatalytic material of the present invention include the following

[0015] Beneficial effects:

[0016] 1. The Ti3C2 / Co9S8 heterojunction photocatalytic material prepared by the present invention can effectively expand the absorption range of visible light and has a wide light absorption range in both the visible light and near-infrared light regions.

[0017] 2. The Ti3C2 / Co9S8 heterojunction photocatalytic material prepared by the present invention comprises Co9S8 nanoflower balls and Ti3C2 nanosheets which are stirred and mixed to further disperse Co9S8 and Ti3C2. The Co9S8 nanoflower balls are ultrasonically treated to form Co9S8 nanosheets which are inserted into the Ti3C2 nanosheet layer to form a heterostructure. The microstructure of the nanosheets inserted into the Ti3C2 intercalation layer accelerates the separation of photogenerated carriers and the transfer of electrons, thereby enhancing the efficiency of the photocatalytic synthesis of H2O2 in water. In addition, the morphology and structural regularity of the Ti3C2 / Co9S8 sample change with the change of the Ti3C2 content.

[0018] 3. The Ti3C2 / Co9S8 heterojunction photocatalytic material prepared by the present invention has a significant restriction on the recombination of photogenerated carriers, and the constructed S-type heterojunction improves the electron transfer ability, electron donor density and e of the composite material. - -h + The Ti3C2-5 / Co9S8 catalyst has an important role in the separation rate. The H2O2 generation concentration in pure water and real seawater without using electron and proton donors is 7.84 mM·h -1 ·g cat -1 and 12.5 mM·h -1 ·g cat -1 .

[0019] 4. The method for preparing the Ti3C2 / Co9S8 heterojunction photocatalytic material of the present invention has the characteristics of simple process, easy operation and low equipment requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 X-ray diffraction patterns of samples Co9S8, Ti3C2 / Co9S8, and Ti3C2. The black line in the figure is pure Co9S8 powder, the green line is the Ti3C2-2 / Co9S8 composite material with a Ti3C2 mass content of 2% (TC-2 / CS), the pink line is the Ti3C2-5 / Co9S8 composite material with a Ti3C2 mass content of 5% (TC-5 / CS), the blue line is the Ti3C2-10 / Co9S8 composite material with a Ti3C2 mass content of 10% (TC-10 / CS), and the purple line is pure Ti3C2 powder;

[0021] Figure 2 Schematic diagram and SEM images of the compositions of samples Co9S8 and TC-5 / CS;

[0022] Figure 3Transient photocurrent response diagram of samples Co9S8, Ti3C2 / Co9S8, and Ti3C2. The black line in the figure is pure Co9S8 powder, the green line is TC-2 / CS composite material, the pink line is TC-5 / CS composite material, the blue line is TC-10 / CS composite material, and the purple line is pure Ti3C2 powder;

[0023] Figure 4 Nyquist plots of samples Co9S8, Ti3C2 / Co9S8, and Ti3C2. The black line is pure Co9S8 powder, the green line is TC-2 / CS composite material, the pink line is TC-5 / CS composite material, the blue line is TC-10 / CS composite material, and the purple line is pure Ti3C2 powder.

[0024] Figure 5 The effects of sample Co9S8, Ti3C2 / Co9S8, and Ti3C2 content on H2O2 yield in pure water and seawater (reaction conditions: 300W Xe lamp, 0.03g photocatalyst, 50mL pure water, pH=7, 20℃). The black line in the figure is pure Co9S8 powder, the green line is TC-2 / CS composite material, the pink line is TC-5 / CS composite material, the blue line is TC-10 / CS composite material, and the purple line is pure Ti3C2 powder.

[0025] Figure 6 Figure 2 shows the recyclability of TC-5 / CS composite materials in seawater (reaction conditions: 300W Xe lamp, 0.03g TC-5 / CS, 50mL seawater, pH=7, 20℃, 1h).

[0026] Figure 7 (a) UV-vis (Ahν) for samples Co9S8 and TC-5 / CS photocatalytic materials 1 / 2 vs (hν) curve; (b) Effect of different free radical scavengers on the yield of photogenerated H2O2 (reaction conditions: 300WXe lamp, 0.05g TC-5 / CS, 50mL H2O, pH = 9, 10℃); (c) ·OH and ·O2 - Radical capture ESR detection spectrum. DETAILED DESCRIPTION

[0027] Specific embodiment 1: The preparation method of the Ti3C2 / Co9S8 heterojunction photocatalytic material in this embodiment is implemented according to the following steps:

[0028] 1. Preparation of Co9S8 matrix:

[0029] Co(NO3)2·6H2O was dissolved in deionized water and stirred to obtain a cobalt nitrate solution. CH3CSNH2 and NaOH were then added to the cobalt nitrate solution in sequence and stirred at room temperature for 1.5 to 3 hours. The solid phase product was washed with water and dried to obtain a Co9S8(CS) matrix.

[0030] 2. Preparation of Ti3C2:

[0031] a. Add titanium aluminum carbide (Ti3AlC2) to a 40 wt.% hydrofluoric acid solution and stir the mixture at room temperature for 45 to 60 hours. Wash and dry the solid phase to obtain a Ti3C2 precursor powder.

[0032] b. Dispersing the precursor Ti3C2 powder in dimethyl sulfoxide (DMSO) solution, stirring for 20 to 30 hours, then ultrasonically treating for 1 to 2 hours, washing and drying to obtain Ti3C2 powder;

[0033] 3. Preparation of Ti3C2 / Co9S8 heterojunction photocatalytic materials:

[0034] The Co9S8 matrix and Ti3C2 powder are mixed and ground to obtain a mixed powder, which is then dispersed in DMSO and stirred at room temperature for 20 to 30 hours, followed by ultrasonic treatment for 1 to 2 hours. The reaction product is washed and dried to obtain a Ti3C2 / Co9S8 heterojunction photocatalytic material.

[0035] In this embodiment, Ti3C2 is compounded with a narrow-bandgap n-type semiconductor material Co9S8 matrix to form a heterojunction catalyst, which expands the absorption range of sunlight, promotes the separation of photoinduced electrons and holes, and improves the photocatalytic performance.

[0036] The preparation method of the Ti3C2 / Co9S8 heterojunction photocatalytic material in this embodiment has the following beneficial effects:

[0037] 1. The Ti3C2 / Co9S8 heterojunction photocatalytic material prepared in this embodiment uses the transition metal sulfide semiconductor material Co9S8 as the matrix and the Mxenes material Ti2C3 to construct an S-type heterostructure, combining the advantages of different materials to form a synergistic effect, enhancing the material's ability to absorb light, expanding the visible light response range of the photocatalytic reaction, promoting the separation of photogenerated electrons and holes, and inhibiting the recombination of photogenerated carriers. By rationally designing the interface structure and regulating the electron transmission path, the selectivity and yield of H2O2 are effectively improved, and the catalyst can be reused more than 5 times.

[0038] 2. The Ti3C2 / Co9S8 heterojunction photocatalytic material prepared in this embodiment does not use pure oxygen or electron proton donors in the photocatalytic H2O2 production process, reducing the need for external oxygen and electron donors and improving the sustainability and economic efficiency of the reaction. Dissolved O2 in water is effectively utilized throughout the process, and the O2 generated during the reaction replenishes the H2O2 yield. The H2O2 yield of the S-type heterojunction catalyst is similar to that of other catalysts using electron and proton donors under the same conditions. This indicates that the synergistic effect of its own photogenerated carriers can also promote the photocatalytic reaction, improving reaction efficiency and selectivity.

[0039] 3. This embodiment prepares a Ti3C2 / Co9S8 heterojunction photocatalytic material. Photocatalytically producing H2O2 from seawater instead of pure water reduces reliance on freshwater resources and lowers production and storage costs. Conventional photocatalysts are susceptible to interference from salt, organic matter, and other impurities in seawater environments. Heterojunction photocatalysts effectively utilize the 3.0-5.0% salt content of seawater and increase H2O2 yield.

[0040] 4. The method for preparing the Ti3C2 / Co9S8 heterojunction photocatalytic material in this embodiment has the characteristics of simple process, easy operation and low equipment requirements.

[0041] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that the concentration of the cobalt nitrate solution in step 1 is 0.02-0.03 g / mL.

[0042] Specific embodiment three: This embodiment differs from specific embodiment one or two in that in step one, 2.5-3.5 g of Co(NO3)2·6H2O is dissolved in 140-160 mL of deionized water and stirred to obtain a cobalt nitrate solution, and then 2.8-3.2 g of CH3CSNH2 and 2-2.4 g of NaOH are sequentially added to the cobalt nitrate solution.

[0043] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that the solid phase product in step 1 is dried at 50° C. for 20 to 26 hours after being washed with water.

[0044] Specific embodiment 5: This embodiment differs from any one of specific embodiments 1 to 4 in that the washing in step a of step 2 is carried out in sequence with water and anhydrous ethanol for sufficient washing.

[0045] Specific embodiment 6: This embodiment differs from specific embodiments 1 to 5 in that in step 2, aluminum titanium carbide is added to a hydrofluoric acid solution with a concentration of 40 wt.%, and the mass volume ratio of aluminum titanium carbide to hydrofluoric acid solution is controlled to be 1 g:20 mL.

[0046] Specific embodiment seven: This embodiment differs from any one of specific embodiments one to six in that the stirring time in step b in step two is 22 to 26 hours, followed by ultrasonic treatment for 1 hour.

[0047] Specific embodiment eight: The difference between this embodiment and any one of specific embodiments one to seven is that in step three, the Co9S8 matrix and the Ti3C2 powder are mixed in a mass ratio of (2.8-3.2): (0.14-0.16).

[0048] Specific embodiment 9: This embodiment differs from any one of specific embodiments 1 to 8 in that in step 3, the mixed powder is dispersed in DMSO, stirred at room temperature for 22 to 26 hours, and then ultrasonically treated for 1 hour.

[0049] Specific embodiment ten: The difference between this embodiment and any one of specific embodiments one to nine is that the content of Ti3C2 in the Ti3C2 / Co9S8 heterojunction photocatalytic material in step three is 5 wt%.

[0050] This embodiment regulates the content of Ti3C2 in the Ti3C2 / Co9S8 heterojunction photocatalytic material. Co9S8 nanosheets loaded with an appropriate amount of Ti3C2 can most effectively separate photogenerated charges and promote electron transfer in the composite material, thereby having higher photocatalytic H2O2 production activity.

[0051] Example 1: The preparation method of the Ti3C2-5 / Co9S8 heterojunction photocatalytic material of this embodiment is implemented according to the following steps:

[0052] 1. Preparation of Co9S8 matrix:

[0053] 3.0 g of Co(NO3)2·6H2O was dissolved in 150 mL of deionized water and stirred to obtain a cobalt nitrate solution. 3.09 g of CH3CSNH2 and 2.2 g of NaOH were then added to the cobalt nitrate solution in sequence and stirred at room temperature for 2 h. The solid phase product was washed with water and dried (dried at 50°C for 24 h) to obtain a black Co9S8(CS) matrix.

[0054] 2. Preparation of Ti3C2:

[0055] a. Add 1 g of titanium aluminum carbide (Ti3AlC2) to 20 mL of a 40 wt.% hydrofluoric acid solution, stir and react at room temperature for 48 h, centrifuge the solid phase, wash it thoroughly with water and anhydrous ethanol, and finally dry it at 60°C for 8 h to obtain a Ti3C2 precursor powder;

[0056] b. The precursor Ti3C2 powder was dispersed in 30 mL of dimethyl sulfoxide (DMSO) solution, stirred for 24 h, and then ultrasonicated for 1 h to promote the delamination of Ti3C2 under ultrasonic conditions. The Ti3C2 was fully washed with water and anhydrous ethanol and dried to obtain Ti3C2 powder;

[0057] 3. Preparation of Ti3C2-5 / Co9S8 heterojunction photocatalytic materials:

[0058] 3 g of Co9S8 matrix and 0.158 g of Ti3C2 powder were mixed and ground to obtain a mixed powder. The mixed powder was dispersed in 25 mL of DMSO, stirred at room temperature for 24 h, and then ultrasonically treated for 1 h. The reaction product was washed three times with water and ethanol, and dried (at 50°C for 24 h) to obtain Ti3C2-5 / Co9S8 heterojunction photocatalytic material (i.e., the Ti3C2 content in the Ti3C2 / Co9S8 heterojunction photocatalytic material is 5 wt%).

[0059] Example 2: The difference between this example and Example 1 is that in step three, 3 g of Co9S8 matrix and 0.062 g of Ti3C2 powder are mixed and ground to obtain a mixed powder, which is dispersed in 25 mL of DMSO and stirred at room temperature for 24 h to obtain Ti3C2-2 / Co9S8 heterojunction photocatalytic material. The other steps and parameters are the same as those in Example 1.

[0060] Example 3: The difference between this example and Example 1 is that in step three, 3 g of Co9S8 matrix and 0.333 g of Ti3C2 powder are mixed and ground to obtain a mixed powder, which is dispersed in 25 mL of DMSO and stirred at room temperature for 24 h to obtain Ti3C2-10 / Co9S8 heterojunction photocatalytic material. The other steps and parameters are the same as those in Example 1.

[0061] Example 4: This example uses only black Co9S8 powder.

[0062] Example 5: This example uses only Ti3C2 powder.

[0063] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0064] like Figure 1As shown, the typical XRD patterns of different Ti3C2 contents in the comparative sample Ti3C2 / Co9S8 composite material at 5°-70°. In the figure, the black line is Co9S8 prepared in step 1 of Example 1, the pink line is Ti3C2-5 / Co9S8 (TC-5 / CS) prepared in Example 1, the green line is Ti3C2-2 / Co9S8 (TC-2 / CS) prepared in Example 2, the blue line is Ti3C2-10 / Co9S8 (TC-10 / CS) prepared in Example 3, and the purple line is Ti3C2 material prepared in step 2 of Example 1;

[0065] from Figure 1 The XRD diffraction peaks of Co9S8 can be identified in the spectrum at 2θ = 16.8°, 29.7°, 31.2°, 47.5°, and 52.3°, respectively. Comparison with the standard spectrum (PDF#03-0631) shows that these peaks correspond to the (111), (311), (222), (511), and (440) crystal planes, respectively. The Co9S8 phase peaks of the Ti3C2 / Co9S8 sample are weaker than those of pure Co9S8, which is due to the covering effect of the Co9S8 layer embedded in the Ti3C2 material. Pure Ti3C2 exhibits diffraction peaks at 2θ = 8.5°, 18.2°, 27.5°, 35.2°, 42.1°, and 61.4°. Based on the standard spectrum (PDF: 00-131-1400), these peaks correspond to the (002), (006), (008), (001), (012), and (110) crystal planes of Ti3C2, respectively. Samples TC-x / CS exhibit typical diffraction peaks of Ti3C2, indicating that the Ti3C2 phase forms an interface structure within the Co9S8 matrix. With increasing Ti3C2 content, the purity of Co9S8 decreases, and the intensity of the Co9S8 diffraction peaks in sample TC-x / CS weakens. Co9S8 nanosheets are affected by the layered structure of Ti3C2, increasing their tendency to form Ti3C2 / Co9S8 heterojunctions. However, after modification with Ti3C2, Co9S8 still maintains a good native structure.

[0066] like Figure 2 As shown, the composition diagram and SEM images of Co9S8 and Ti3C2-5 / Co9S8;

[0067] from Figure 2 SEM images clearly show the Co9S8 matrix as clusters of aggregated nanoflower balls. After the Ti3C2 is introduced into the matrix, irregular layers of Co9S8 nanosheets are distributed within the intercalated layers. The Co9S8 nanosheets are directly embedded between the Ti3C2 "sheets," and a tightly bound overlap exists between the two phases, further supporting the successful intercalation.

[0068] like Figure 3 As shown, the transient photocurrent response diagrams of the samples Co9S8 and Ti3C2 / Co9S8. In the figure, the black line represents the sample Co9S8, the purple line represents the sample Ti3C2, the red line represents TC-5 / CS prepared in Example 1, the green line represents TC-2 / CS prepared in Example 2, and the blue line represents the transient photocurrent response diagram of TC-10 / CS prepared in Example 3;

[0069] From Figure 3 it can be seen that the transient photocurrent response intensities are in the order of Ti3C2 < Co9S8 < TC-10 / CS < TC-2 / CS < TC-5 / CS, indicating that the introduction of Ti3C2 into the Co9S8 matrix can improve the photogenerated electron transport ability of the matrix nanosheets. The transient photocurrent response of TC-5 / CS is higher than that of the other 4 samples, indicating that an appropriate Ti3C2 content promotes the electron transport ability of the TC-x / CS composite materials.

[0070] As Figure 4 shown, the Nyquist curve diagrams of the samples Co9S8, Ti3C2 / Co9S8, and Ti3C2. In the figure, the black line represents pure Co9S8 powder, the green line represents the TC-2 / CS composite material, the pink line represents the TC-5 / CS composite material, the blue line represents the TC-10 / CS composite material, and the purple line represents pure Ti3C2 powder;

[0071] From Figure 4 it can be clearly seen that the impedance radius of the pure Co9S8 sample is the largest. After the introduction of Ti3C2 into the Co9S8 matrix, the impedance radius significantly decreases until the loading amount reaches 10 wt.%. The Co9S8 nanosheets loaded with an appropriate amount of Ti3C2 can most effectively separate photogenerated charges and promote the electron transfer of the composite material, while the overloaded Ti3C2 increases the resistance to the separation of e - -h + pairs. This result also coincides with the Figure 3 conclusion.

[0072] As Figure 5 shown, the influence of the Ti3C2 content of the samples Co9S8, Ti3C2 / Co9S8, and Ti3C2 on the H2O2 production rate in pure water and seawater (reaction conditions: 300W Xe lamp, 0.03g photocatalyst, 50mL pure water, pH = 7, 20°C). In the figure, the black line represents pure Co9S8 powder, the green line represents the TC-2 / CS composite material, the pink line represents the TC-5 / CS composite material, the blue line represents the TC-10 / CS composite material, and the purple line represents pure Ti3C2 powder;

[0073] From Figure 5It can be seen that the H2O2 production of samples TC-2 / CS, TC-5 / CS, and TC-10 / CS in pure water after 2h of photoreaction can reach 5.62mM·h -1 ·g cat -1 , 7.40 mM·h -1 ·g cat -1 and 5.61 mM·h -1 ·g cat -1 In the TC-5 / CS structure, Ti3C2 and the matrix material are dispersed more evenly, which has higher photoelectron transport, carrier density and e - -h + The composite inhibition ability is achieved, and a good synergistic effect is obtained in the photocatalytic process, effectively achieving the highest H2O2 yield among the samples. The H2O2 yield of the sample TC-x / CS in seawater is significantly improved compared with pure water. After TC-x / CS forms a heterojunction, it produces a good synergistic effect with specific ions in seawater, which increases the H2O2 yield. TC-5 / CS can produce 12.48mM·h in 2h. -1 ·gcat -1 , which is 1.69 times that of pure water.

[0074] like Figure 6 As shown, the recycling regeneration ability of TC-5 / CS composite material in seawater (reaction conditions: 300W Xe lamp, 0.03g TC-5 / CS, 50mL seawater, pH=7, 20℃, 1h);

[0075] from Figure 6 It can be seen that after the deactivated photocatalyst is treated with a mixed solution of CH3CSNH2 and NaOH, the treated photocatalyst can be reused more than 5 times without a significant decrease in H2O2 yield.

[0076] like Figure 7 As shown, the sample Co9S8 and TC-5 / CS photocatalytic materials (a) UV-vis (Ahν) 1 / 2 vs (hν) curve; (b) the effect of different free radical scavengers on the photogenerated H2O2 yield (reaction conditions: 300W Xe lamp, 0.05g TC-5 / CS, 50mLH2O, pH = 9, 10℃); (c) ·OH and ·O2 - Free radical capture ESR detection spectrum;

[0077] from Figure 7 As can be seen from the figure, the E VB and E CB The calculated values ​​are 1.61 eV and -0.37 eV, respectively. - The presence of the trapping agent DMSO severely reduced the yield of H2O2, confirming that e- It is the main active species for the two-electron reduction of O2 to produce H2O2. Strong DMPO-·O2 can be observed in pure water and seawater. - The signal in seawater is stronger than that in pure water, and the signal of TC-5 / CS is stronger than that of pure Co9S8. The above results indicate that the presence of Ti3C2 intercalation helps to open up an auxiliary channel for the single-electron reduction of O2.

[0078] In summary, the Ti3C2-5 / Co9S8 composite material prepared in Example 1 has high photocatalytic H2O2 production activity and excellent stability, and can be used as a new material for photocatalytic preparation of H2O2.

Claims

1. A method for preparing a two-dimensional nano-titanium carbide / cobalt octasulfide heterojunction photocatalytic material, characterized in that The preparation method is achieved by the following steps:

1. Preparation of Co9S8 matrix: Co(NO3)2•6H2O was dissolved in deionized water and stirred to obtain a cobalt nitrate solution. Then CH3CSNH2 and NaOH were added to the cobalt nitrate solution in sequence and stirred at room temperature for 1.5-3 hours. The solid phase product was washed with water and dried to obtain a Co9S8 matrix.

2. Preparation of Ti3C2: a. Add aluminum titanium carbide to a 40 wt.% hydrofluoric acid solution and stir the mixture at room temperature for 45-60 hours. The solid phase is washed and dried to obtain a precursor Ti3C2 powder. b. Disperse the precursor Ti3C2 powder in dimethyl sulfoxide solution, stir for 20-30 hours, then ultrasonicate for 1-2 hours, and obtain Ti3C2 powder after washing and drying; 3. Preparation of Ti3C2 / Co9S8 heterojunction photocatalytic materials: Co9S8 matrix and Ti3C2 powder were mixed in a mass ratio of (2.8~3.2): (0.14~0.16), ground to obtain a mixed powder, dispersed in DMSO, stirred at room temperature for 20~30 hours, and then ultrasonically treated for 1~2 hours. The reaction product was washed and dried to obtain Ti3C2 / Co9S8 heterojunction photocatalytic material.

2. The method for preparing the two-dimensional nano-titanium carbide / nonacobalt octasulfide heterojunction photocatalytic material according to claim 1, characterized in that The concentration of the cobalt nitrate solution in step 1 is 0.02-0.03 g / mL.

3. The method for preparing the two-dimensional nano-titanium carbide / nonacobalt octasulfide heterojunction photocatalytic material according to claim 1, characterized in that In step 1, 2.5-3.5 g of Co(NO3)2•6H2O was dissolved in 140-160 mL of deionized water and stirred to obtain a cobalt nitrate solution. 2.8-3.2 g of CH3CSNH2 and 2-2.4 g of NaOH were then added to the cobalt nitrate solution in sequence.

4. The method for preparing the two-dimensional nano-titanium carbide / nonacobalt octasulfide heterojunction photocatalytic material according to claim 1, characterized in that The solid phase product in step 1 was washed with water and then dried at 50°C for 20-26 h.

5. The method for preparing the two-dimensional nano-titanium carbide / nonacobalt octasulfide heterojunction photocatalytic material according to claim 1, characterized in that In step 2, aluminum titanium carbide is added to a hydrofluoric acid solution having a concentration of 40 wt.%, and the mass volume ratio of aluminum titanium carbide to the hydrofluoric acid solution is controlled to be 1 g:20 mL.

6. The method for preparing the two-dimensional nano-titanium carbide / nonacobalt octasulfide heterojunction photocatalytic material according to claim 1, characterized in that In step 2, the stirring time of step b is 22 to 26 hours, followed by ultrasonic treatment for 1 hour.

7. The method for preparing the two-dimensional nano-titanium carbide / nonacobalt octasulfide heterojunction photocatalytic material according to claim 1, characterized in that In step 3, the mixed powder was dispersed in DMSO, stirred at room temperature for 22-26 h, and then ultrasonicated for 1 h.

8. The method for preparing the two-dimensional nano-titanium carbide / nonacobalt octasulfide heterojunction photocatalytic material according to claim 1, characterized in that The content of Ti3C2 in the Ti3C2 / Co9S8 heterojunction photocatalytic material in step three is 5wt%.

9. Application of the two-dimensional nano-titanium carbide / nonacobalt octasulfide heterojunction photocatalytic material prepared by the method of claim 1, characterized in that The Ti3C2 / Co9S8 heterojunction photocatalytic material was applied to photocatalytic H2O production of H2O2.

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