Sulfur vacancy Co3O4 / CdIn2S4-Vs composite material as well as preparation method and application thereof
By constructing sulfur vacancies on the surface of CdIn2S4 and loading Co3O4 to form a Co3O4/CdIn2S4-Vs composite material, the problem of low photocatalytic hydrogen production efficiency was solved, and efficient photogenerated carrier separation and significant photocatalytic hydrogen production effect were achieved.
Patent Information
- Application Number
- CN202512001494.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-29
- Publication Date
- 2026-02-24
AI Technical Summary
Current photocatalytic hydrogen production efficiency is low and cannot meet the needs of practical applications, so there is a need to develop high-performance photocatalysts.
Sulfur vacancies on the surface of CdIn2S4 were constructed by etching with H2O2 and then loaded with Co3O4 to form a Co3O4/CdIn2S4-Vs composite material. The sulfur vacancies were used as electron traps to accelerate the separation of photogenerated carriers.
It significantly improved the separation efficiency of photogenerated carriers, and the photocatalytic hydrogen production rate reached 10.378 mmol h⁻¹g⁻¹, which is 43 times that of pure CdIn₂S₄, while maintaining a cycle performance of 93%.
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Figure CN121551028A_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of catalyst preparation technology, specifically relating to a sulfur vacancy Co3O4 / CdIn2S4-Vs composite material, its preparation method and application. Background Technology
[0002] Hydrogen energy, as a secondary energy source, possesses unique advantages: it can be regenerated through various pathways, including fossil fuels and renewable energy sources, fully aligning with the concept of sustainable development. In particular, the method of using solar energy to split water to produce hydrogen directly combines renewable energy with hydrogen production, demonstrating broad application prospects. However, despite the significant attention garnered for solar water splitting hydrogen production technology, the efficiency of photocatalytic hydrogen production remains relatively low, far from meeting the demands of practical applications. Achieving efficient and stable hydrogen production hinges on developing high-performance photocatalysts. To this end, researchers worldwide are extensively exploring various semiconductor materials in an effort to overcome the bottleneck in photocatalytic hydrogen production efficiency and drive the rapid development of the hydrogen energy industry. Summary of the Invention
[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a sulfur vacancy Co3O4 / CdIn2S4-Vs composite material, its preparation method, and its application. Specifically, the following technical solution is adopted: In a first aspect, the present invention provides a method for preparing a sulfur vacancy Co3O4 / CdIn2S4-Vs composite material, comprising the following steps: CdIn2S4 nanomaterials were placed in H2O2 solution, stirred, washed, and dried to obtain CdIn2S4-Vs nanomaterials with S vacancies. Co3O4 and the CdIn2S4-Vs nanomaterials were placed in anhydrous ethanol, stirred, washed, and dried to obtain the sulfur vacancy Co3O4 / CdIn2S4-Vs composite material.
[0004] This invention utilizes H2O2 etching to introduce S vacancies into CdIn2S4 and loads Co3O4 onto CdIn2S4-Vs via electrostatic self-assembly, designing a series of Co3O4 / CdIn2S4-Vs composite materials. Among these, appropriate construction defects on the CdIn2S4 surface can form electron traps, thereby accelerating the separation of photogenerated carriers, significantly improving its hydrogen evolution efficiency under visible light, and suppressing the intrinsic photocorrosion of sulfides.
[0005] As a further preferred embodiment, the concentration of the H2O2 solution is 5 M.
[0006] As a further preferred embodiment, the CdIn2S4 nanomaterials are placed in an H2O2 solution and stirred for 10-60 seconds.
[0007] As a further preferred embodiment, the mass ratio of the Co3O4 to the CdIn2S4-Vs nanomaterial is 3-7:93-97.
[0008] As a further preferred embodiment, the method for preparing Co3O4 includes the following steps: Cobalt chloride and urea were dissolved in water and then heated to 100°C. After the reaction was completed, the mixture was cooled, centrifuged, washed, and dried to obtain the precursor material. The precursor material was placed in a muffle furnace and calcined at 400°C. After calcination, Co3O4 nanomaterials were obtained.
[0009] As a further preferred embodiment, the preparation method of the CdIn2S4 nanomaterial includes the following steps: Nitric acid tetrahydrate and indium nitrate tetrahydrate were dissolved in water and sonicated to obtain a mixed solution. Thioacetamide is dissolved in water to obtain a thioacetamide solution; The mixed solution and the thioacetamide solution were mixed evenly, and then placed in a reaction vessel and heated at 80°C for reaction. After the reaction was completed, the mixture was washed and dried to obtain the CdIn2S4 nanomaterial.
[0010] As a further preferred embodiment, the molar ratio of nitric acid tetrahydrate, indium nitrate tetrahydrate, and thioacetamide is 1:2:4.
[0011] Secondly, the present invention provides a sulfur vacancy Co3O4 / CdIn2S4-Vs composite material, which is prepared by the above-described preparation method.
[0012] Thirdly, the present invention provides the application of the sulfur vacancy Co3O4 / CdIn2S4-Vs composite material in photocatalytic hydrogen production.
[0013] The beneficial effects of this invention are as follows: This invention constructs CdIn2S4 with surface sulfur vacancies (CIS-Vs) by etching with H2O2, and then loads Co3O4 to obtain a Co3O4 / CIS-Vs composite material. The surface sulfur vacancies act as electron traps, promoting the rapid transfer of photogenerated electrons in CdIn2S4, thereby significantly improving the separation efficiency of photogenerated carriers. The method for constructing surface sulfur vacancies in CdIn2S4 is simple and low-cost. Photocatalytic hydrogen production performance tests and cycling tests show that the optimal photocatalytic hydrogen production rate of the Co3O4 / CIS-Vs composite material reaches 10.378 mmol / h. -1 g -1It is 43 times that of pure CdIn2S4, and its performance can still be maintained at 93% after cyclic experiments. Attached Figure Description
[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0015] Figure 1 The image shows the XRD patterns of different materials; Figure 2 The following are the Cd 3d elemental spectra (a), In 3d elemental spectra (b), S 2p elemental spectra (c) for CIS, CIS-Vs, and CC-Vs, and the Co 2p elemental spectra (d) and O 1s elemental spectra (e) for Co3O4 and CC-Vs. Figure 3 The EPR spectrum of the 5CC-Vs composite material is shown below. Figure 4 The images shown are: SEM images of Co3O4 (a), CIS (b) and CC-Vs (c); TEM image of CC-Vs (d); HRTEM image of 5CC-Vs (e); magnified HRTEM image (f); HAADF image (g); and elemental spectrum (hl). Figure 5 The image shows the UV-Vis diffuse reflectance spectra (a) and bandgap (b) of different materials; Figure 6 The figures shown are Mott-Schottky curves for CIS-Vs (a) and Co3O4 (b). Figure 7 The images show the photoluminescence (a), photocurrent (b), and AC impedance (c) diagrams of different materials. Figure 8 The figure shows the photocatalytic hydrogen production performance and cycle test results of different materials; Figure 9 The diagram shows the photocatalytic reaction mechanism of the sulfur vacancy Co3O4 / CdIn2S4-Vs composite material. Detailed Implementation
[0016] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0017] Example 1 A method for preparing a sulfur vacancy Co3O4 / CdIn2S4-Vs composite material, which specifically includes the following steps: (1) Preparation of CdIn2S4 nanomaterials 1 mmol of cadmium nitrate tetrahydrate (Cd(NO3)2·4H2O) and 2 mmol of indium nitrate tetrahydrate (In(NO3)3·4H2O) were added to beakers, along with 30 mL of deionized water. To ensure complete dissolution, the mixture was sonicated for 10 min. Simultaneously, 4 mmol of thioacetamide was added to 20 mL of deionized water and stirred until completely dissolved. The two solutions were then mixed and stirred continuously for 30 min to ensure homogeneity. The resulting mixture was transferred to a 100 mL reactor and heated at 80 °C for 6 h. After the reaction was complete, the product was washed multiple times with deionized water and ethanol to remove impurities. The washed product was then dried in a vacuum drying oven at 60 °C for 12 h to obtain the pure and dry target product, CdIn2S4 nanomaterials (denoted as CIS).
[0018] (2) Preparation of CdIn2S4-Vs nanomaterials 0.3 g of CdIn2S4 was added to a 5 M H2O2 solution and stirred for 30 s. The mixture was then filtered, washed several times with deionized water, and finally dried under vacuum in a 60 °C oven for 12 h to obtain CdIn2S4-Vs nanomaterials (denoted as CIS-Vs-30s).
[0019] (3) Preparation of Co3O4 nanomaterials First, appropriate amounts of cobalt chloride (CoCl2·6H2O) and urea (CO(NH2)2) were added to a beaker, along with 50 mL of deionized water. The mixture was stirred with a magnetic stirrer for 30 min to ensure complete dissolution and uniform distribution of all solids. Subsequently, the mixture was transferred to a 100 mL reactor and heated at 100 °C for 8 h. After the reaction was complete, the product was allowed to cool naturally to room temperature in the reactor. After cooling, the product was collected by centrifugation, and the supernatant was removed. Next, the product was washed multiple times with deionized water and ethanol, and the resulting material was dried in a vacuum drying oven at 60 °C for 12 h to obtain the precursor material. Finally, the precursor material was placed in a muffle furnace and calcined at 400 °C for 1 h to obtain Co3O4 nanomaterials.
[0020] (4) Preparation of Co3O4 / CdIn2S4-Vs composite material Weigh 3 mg Co3O4 and 97 mg CdIn2S4-Vs and add them to a beaker containing 30 ml of anhydrous ethanol. Stir for 24 h. The resulting mixture is then washed several times with anhydrous ethanol and deionized water. The washed composite material is dried in an oven at 60 °C for 24 h to obtain the final product Co3O4 / CdIn2S4-Vs composite material (where the Co3O4 content is 3%, denoted as 3CC-Vs-30s).
[0021] Example 2 A method for preparing a sulfur vacancy Co3O4 / CdIn2S4-Vs composite material is similar to that in Example 1, except that "stirring for 30 s" in step (2) of Example 1 is replaced with "stirring for 10 s" to obtain CdIn2S4-Vs nanomaterial (denoted as CIS-Vs-10s). The remaining steps are the same as in Example 1 to obtain the Co3O4 / CdIn2S4-Vs composite material (denoted as 3CC-Vs-10s).
[0022] Example 3 A method for preparing a sulfur vacancy Co3O4 / CdIn2S4-Vs composite material is similar to that in Example 1, except that "stirring for 30 s" in step (2) of Example 1 is replaced with "stirring for 60 s" to obtain CdIn2S4-Vs nanomaterial (denoted as CIS-Vs-60s). The remaining steps are the same as in Example 1 to obtain the Co3O4 / CdIn2S4-Vs composite material (denoted as 3CC-Vs-60s).
[0023] Example 4 A method for preparing a sulfur vacancy Co3O4 / CdIn2S4-Vs composite material is similar to that in Example 1. The only difference is that "3mg Co3O4 and 97mg CdIn2S4-Vs" in step (4) of Example 1 is replaced with "5mg Co3O4 and 95mg CdIn2S4-Vs". The remaining steps are the same as in Example 1, and the Co3O4 / CdIn2S4-Vs composite material (where the Co3O4 content is 5%, denoted as 5CC-Vs-30s) is obtained.
[0024] Example 5 A method for preparing a sulfur vacancy Co3O4 / CdIn2S4-Vs composite material is similar to that in Example 1. The only difference is that "3mg Co3O4 and 97mg CdIn2S4-Vs" in step (4) of Example 1 is replaced with "7mg Co3O4 and 93mg CdIn2S4-Vs". The remaining steps are the same as in Example 1, and the Co3O4 / CdIn2S4-Vs composite material (where the Co3O4 content is 7%, denoted as 7CC-Vs-30s) is obtained.
[0025] Example 6 A method for preparing a sulfur vacancy Co3O4 / CdIn2S4-Vs composite material is similar to that in Example 1, except that "stirring for 30 s" in step (2) of Example 1 is replaced with "stirring for 10 s" to obtain CdIn2S4-Vs nanomaterial (denoted as CIS-Vs-10s). In step (4) of Example 1, "3 mg Co3O4 and 97 mg CdIn2S4-Vs" is replaced with "5 mg Co3O4 and 95 mg CdIn2S4-Vs". The remaining steps are the same as in Example 1 to obtain a Co3O4 / CdIn2S4-Vs composite material (where the Co3O4 content is 5%, denoted as 5CC-Vs-10s).
[0026] Example 7 A method for preparing a sulfur vacancy Co3O4 / CdIn2S4-Vs composite material is similar to that in Example 1, except that "stirring for 30 s" in step (2) of Example 1 is replaced with "stirring for 60 s" to obtain CdIn2S4-Vs nanomaterial (denoted as CIS-Vs-60s). In step (4) of Example 1, "3 mg Co3O4 and 97 mg CdIn2S4-Vs" is replaced with "5 mg Co3O4 and 95 mg CdIn2S4-Vs". The remaining steps are the same as in Example 1 to obtain a Co3O4 / CdIn2S4-Vs composite material (where the Co3O4 content is 5%, denoted as 5CC-Vs-60s).
[0027] Example 8 A method for preparing a sulfur vacancy Co3O4 / CdIn2S4-Vs composite material is similar to that in Example 1, except that "stirring for 30 s" in step (2) of Example 1 is replaced with "stirring for 10 s" to obtain CdIn2S4-Vs nanomaterial (denoted as CIS-Vs-10s). In step (4) of Example 1, "3 mg Co3O4 and 97 mg CdIn2S4-Vs" is replaced with "7 mg Co3O4 and 93 mg CdIn2S4-Vs". The remaining steps are the same as in Example 1 to obtain a Co3O4 / CdIn2S4-Vs composite material (where the Co3O4 content is 7%, denoted as 7CC-Vs-10s).
[0028] Example 9 A method for preparing a sulfur vacancy Co3O4 / CdIn2S4-Vs composite material is similar to that in Example 1, except that "stirring for 30 s" in step (2) of Example 1 is replaced with "stirring for 60 s" to obtain CdIn2S4-Vs nanomaterial (denoted as CIS-Vs-60s). In step (4) of Example 1, "3 mg Co3O4 and 97 mg CdIn2S4-Vs" is replaced with "7 mg Co3O4 and 93 mg CdIn2S4-Vs". The remaining steps are the same as in Example 1 to obtain a Co3O4 / CdIn2S4-Vs composite material (where the Co3O4 content is 7%, denoted as 7CC-Vs-60s).
[0029] Comparative Example 1 A method for preparing a Co3O4 / CdIn2S4 composite material, which specifically includes the following steps: (1) Preparation of CdIn2S4 nanomaterials 1 mmol of cadmium nitrate tetrahydrate (Cd(NO3)2·4H2O) and 2 mmol of indium nitrate tetrahydrate (In(NO3)3·4H2O) were added to beakers, along with 30 ml of deionized water. To ensure complete dissolution, the mixture was sonicated for 10 min. Simultaneously, 4 mmol of thioacetamide was added to 20 ml of deionized water and stirred until completely dissolved. The two solutions were then mixed and stirred continuously for 30 min to ensure homogeneity. The resulting mixture was transferred to a 100 ml reactor and heated at 80 °C for 6 h. After the reaction was complete, the product was washed multiple times with deionized water and ethanol to remove impurities. The washed product was then dried in a vacuum drying oven at 60 °C for 12 h to obtain the pure and dry target product, CdIn2S4 nanomaterials (denoted as CIS).
[0030] (2) Preparation of Co3O4 nanomaterials First, appropriate amounts of cobalt chloride (CoCl2·6H2O) and urea (CO(NH2)2) were added to a beaker, along with 50 mL of deionized water. The mixture was stirred with a magnetic stirrer for 30 min to ensure complete dissolution and uniform distribution of all solids. Subsequently, the mixture was transferred to a 100 mL reactor and heated at 100 °C for 8 h. After the reaction was complete, the product was allowed to cool naturally to room temperature in the reactor. After cooling, the product was collected by centrifugation, and the supernatant was removed. Next, the product was washed multiple times with deionized water and ethanol, and the resulting material was dried in a vacuum drying oven at 60 °C for 12 h to obtain the precursor material. Finally, the precursor material was placed in a muffle furnace and calcined at 400 °C for 1 h to obtain Co3O4 nanomaterials.
[0031] (3) Preparation of Co3O4 / CdIn2S4 composite material Weigh 5 mg Co3O4 and 95 mg CdIn2S4-Vs and add them to a beaker containing 30 ml of anhydrous ethanol. Stir for 24 h. The resulting mixture is then washed several times with anhydrous ethanol and deionized water. The washed composite material is dried in an oven at 60 °C for 24 h to obtain the final product Co3O4 / CdIn2S4 composite material (where the Co3O4 content is 5%, denoted as 5CC).
[0032] Example 10 The phase structure of the material prepared above was characterized, and the specific process is as follows: The phase composition of the material in the range of 10°–70° was analyzed using X-ray diffraction (XRD) with Cu Kα as the radiation source in a D8 ADVANCE diffractometer at a scan rate of 5° / min. The microstructure of the material was observed using transmission electron microscopy (TEM). The elemental composition and chemical state changes of the catalyst were determined using X-ray photoelectron spectroscopy (XPS). The light absorption properties of the prepared material were tested using ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS). Photoluminescence (PL) of the catalyst was measured using a HITACHIF-7000 fluorescence spectrophotometer at an excitation wavelength of 380 nm.
[0033] (1) In order to further investigate the crystal structure and phase composition of the sample, X-ray diffraction (XRD) analysis was performed on it, and the results are as follows: Figure 1As shown in the figure, obvious diffraction peaks can be observed at 23.18°, 27.25°, 33.00°, 43.32°, and 47.41°. By comparing with the standard diffraction card (JCPDS#27-0060), these diffraction peaks correspond to the (220), (311), (400), (511), and (440) crystal planes of CIS, respectively. This result fully demonstrates that the CIS material has been successfully synthesized, and its crystal structure exhibits typical CIS characteristics. For the synthesized Co3O4 material, its XRD pattern shows significant diffraction peaks at 19.00°, 31.27°, 36.85°, 44.81°, 59.36°, and 65.23°. These diffraction peaks are consistent with the standard diffraction card of Co3O4 (JCPDS#42-1467), corresponding to the (111), (220), (311), (400), (511), and (440) crystal planes of Co3O4, respectively. This result confirms that the Co3O4 material has been successfully synthesized and has high phase purity. However, no obvious diffraction peaks of Co3O4 were observed in CC-Vs, which may be due to the low loading of Co3O4.
[0034] (2) In order to determine the photoelectron spectrum of the sample, XPS analysis was performed on the sample, and the results are as follows: Figure 2 As shown in the figure, CIS exhibits two peaks at 405.46 eV and 412.21 eV, corresponding to Cd 3d... 5 / 2 and Cd 3d 3 / 2 This indicates that Cd is Cd 2+ It exists in the form of Cd 3d. Compared with pure CIS, the binding energy of Cd 3d in CIS-Vs is shifted to a higher angle by 0.2 eV; while compared with CIS-Vs, the binding energy of Cd 3d in CC-Vs is shifted to a lower angle by 0.2 eV. Figure 2 (b) shows the elemental spectrum of In 3d. As can be seen from the figure, CIS has two peaks at 445.11 and 452.64 eV, corresponding to In 3d, respectively. 5 / 2 and In 3d 3 / 2 This indicates that In is In 3+ It exists in the form of In 3d. Compared with pure CIS, the binding energy of In 3d in CIS-Vs is shifted to a higher angle by 0.3 eV; while compared with CIS-Vs, the binding energy of Cd 3d in CC-Vs is shifted to a lower angle by 0.3 eV. Figure 2 (c) shows the elemental spectrum of S2p. The peaks at binding energies of CIS at 161.86 eV and 162.95 eV are attributed to S2p. 3 / 2 and S2p 1 / 2 The orbit indicates that S is in S 2-The elements Cd, In, and S are present in a form that, compared to pure CIS, exhibit a shift in binding energy at higher angles in CIS-Vs, indicating electron transfer within the CIS. Furthermore, after loading Co3O4 to form CC-Vs composites, the binding energies of Cd, In, and S decrease, suggesting that CIS-Vs have accepted electrons. Figure 2 (d) shows the elemental spectrum of Co 2p, with the binding energies of 794.61 eV and 779.68 eV peaks corresponding to Co. 2+ The peaks at 796.14 eV and 781.09 eV are related to Co. 3+ The results confirmed the successful synthesis of Co3O4. Figure 2 (e) shows the elemental spectrum of O 1s, with peaks at binding energies of 5332.67 eV, 531.12 eV, and 29.94 eV representing chemisorbed oxygen, hydroxyl oxygen, and lattice oxygen, respectively. Analysis of the elemental spectra of Co and O revealed that the binding energy of CC-Vs was higher than that of Co3O4, indicating electron transfer from Co3O4. In summary, after the formation of CC-Vs from CIS-Vs and Co3O4, electrons from Co3O4 were transferred, and CIS-Vs accepted electrons from Co3O4.
[0035] (3) To determine the presence of sulfur vacancies in the material, the 5CC-Vs composite material was characterized by electron paramagnetic resonance (EPR), and the test results are as follows: Figure 3 As shown in the figure, a distinct singlet signal with a g-value of 2.004 can be observed, which is higher than the g-value of free electrons (2.0023). This result indicates the presence of paramagnetic defect centers in the sample. Combined with the electronic structure characteristics of sulfur vacancies, this signal can be attributed to unpaired electrons generated by sulfur vacancies. The formation of sulfur vacancies disrupts the local charge balance, allowing electrons to occupy the 3p orbitals of sulfur. Simultaneously, due to spin-orbit coupling effects and crystal field inhomogeneity, the g-value shifts towards higher fields. The above analysis demonstrates that sulfur vacancies have been successfully constructed in the material.
[0036] (4) Morphology and microstructure analysis of the sample To investigate the microstructure and structural characteristics of the samples in depth, various testing methods, including scanning electron microscopy (SEM) and transmission electron microscopy (TEM), were employed, and the results were analyzed in detail. The results are as follows: Figure 4 As shown. Figure 4 (a) shows a scanning electron microscope image of Co3O4. It can be clearly seen that Co3O4 exhibits a rod-like structure composed of tightly packed fine particles. Figure 4 (b) is a scanning electron microscope image of CIS, showing that CIS exhibits a typical granular structure. Figure 4(d) is a transmission electron microscope (TEM) image of 5CC-Vs. It is clearly visible in the image that the CIS substrate material exists in the form of nanoparticles, uniformly loaded with Co3O4 particles, forming a composite structure. To further investigate the contact morphology between CIS and Co3O4, a high-resolution TEM image of 5CC-Vs is presented. Figure 4 (e) and 4 (f)). Through observation and measurement, two different crystal structures were discovered. The crystal plane with an interplanar spacing of 0.323 nm belongs to the (311) crystal plane of CIS, while the crystal plane with an interplanar spacing of 0.241 nm belongs to the (311) crystal plane of Co3O4. This indicates that CIS-Vs and Co3O4 successfully formed a heterojunction. Figure 4 (hl) shows the elemental mapping images of the 5CC-Vs composite material. Analysis of these images shows that the elements are uniformly distributed in the composite material without obvious segregation, further demonstrating the successful synthesis of the composite material.
[0037] (5) Band structure analysis of the sample The light absorption capacity and response range of the material were evaluated using ultraviolet-visible diffuse reflectance spectroscopy, and the results are as follows: Figure 5 As shown in (a), it is evident that after loading Co3O4 onto CIS-Vs, the synthesized CC-Vs composite material exhibits significantly enhanced light absorption compared to pure CIS and CIS-Vs. Furthermore, a redshift is also observed within the light absorption range. This indicates that loading Co3O4 contributes to improving the light-harvesting ability of CIS-Vs and expanding the photoresponse range. Figure 5 The data in (a) is processed using... (αhν) 1 / n = A(hν / E g ) Formula for deriving the bandgap width (E) of the material g The result is as follows Figure 5 As shown in (b). E values of CIS, CIS-Vs, Co3O4, and 5CC-Vs g The values were 2.34 eV, 2.28 eV, 2.14 eV and 1.92 eV, respectively.
[0038] Example 11 The material prepared above was subjected to material property testing, and the specific process is as follows: (1) Photoelectrochemical testing To investigate the photoelectrochemical properties of the samples, tests were conducted in a conventional three-electrode CHI660E workstation. Platinum wire, Ag / AgCl, and an FTO substrate coated with a photocatalyst were used as the counter, reference, and working electrodes, respectively. The electrolyte was 0.1 M Na₂SO₄ solution. A 300 W xenon lamp (CEL-HXF300-T3) was used as the light source. The xenon lamp was turned on and off to measure the photocurrent under light and darkness. Electrochemical impedance spectroscopy (EIS) was performed from 0.1 Hz to 100 kHz. Mott-Scottky curves (MS) were measured at frequencies of 500 Hz, 1000 Hz, and 1500 Hz. The AC voltage was set to 1 V.
[0039] To obtain the precise band structure of the materials, Mott-Schottky tests were performed on CIS-Vs and Co3O4, and the results are as follows: Figure 6 As shown. Flat band potential (E) of the material. fb The flat band potentials of CIS-Vs and Co3O4 can be determined by plotting the tangent line of the curve about the x-axis. The flat band potentials are -1.14 V (vs Ag / AgCl) and -1.18 V (vs Ag / AgCl), respectively. The flat band potentials of the materials relative to the standard hydrogen electrode can be obtained by the formula: E fb (vs NHE) = E Ag / AgCl + 0.059 pH + E o Ag / AgCl Here, E 0 Ag / AgCl The voltage was 0.197 eV, and the pH was 6.5. Furthermore, the slopes of the CIS-Vs and Co3O4 curves were positive, indicating that they belong to the n-type semiconductor category. Typically, the conduction band potential (E) of this semiconductor is... CB The potential is approximately 0.3 eV lower than the flat band potential. Therefore, the E of CIS-Vs and Co3O4 is... CB The values are -0.86 eV and -0.90 eV, respectively.
[0040] To investigate the separation and transfer efficiency of photogenerated carriers in the prepared samples, a series of electrochemical performance tests were performed. The results of the photoluminescence (PL) spectroscopy are as follows: Figure 7 As shown in (a), this test measures the fluorescence intensity generated during photogenerated carrier recombination, thus indicating the extent of the recombination process. Clearly, recombination of photogenerated carriers is most pronounced in pure CIS, while it is least pronounced in the 5CC-Vs composite material. Furthermore, the transient photocurrent test results for each material are as follows: Figure 7As shown in (b), it can be clearly seen that pure CIS has the lowest photocurrent density, while the CC-Vs composite material has a satisfactory photocurrent density. Among them, the 5CC-Vs composite material has the highest photocurrent density. Figure 7 (c) Electrochemical impedance spectroscopy (EIS) testing. In this test, the radius of the curve serves as the basis for determining the charge transfer resistance of the material. A smaller curve radius indicates a lower charge transfer resistance. It is evident from the figure that CIS exhibits the highest charge transfer resistance, while 5CC-Vs shows the lowest. Notably, the CC-Vs composite material formed by modifying CIS and then loading Co3O4 demonstrates significant advantages in terms of photogenerated carrier recombination, photocurrent density, and charge transfer resistance. All the above experimental results indicate that loading Co3O4 onto CIS-Vs accelerates the separation of photogenerated electron-hole pairs.
[0041] (2) Photocatalytic performance test Weigh 10 mg of sample into a 60 mL quartz tube, add 8 mL of deionized water and 2 mL of triethanolamine, seal the tube, and sonicate to disperse the catalyst evenly. Then, purge the quartz tube with Ar gas for 30 min to completely remove air. Use a 300 W xenon lamp (CEL-HXF300-T3) with an output wavelength greater than 420 nm as the light source, and irradiate continuously for 2 h, stirring continuously with a magnetic stirrer during the reaction. After irradiation, extract the gas sample and inject it into a Panuo A91 gas chromatograph for testing, finally determining the hydrogen production rate of the sample.
[0042] The photocatalytic hydrogen evolution performance of the material was studied using triethanolamine as a sacrificial reagent. After 2 hours of light irradiation, the hydrogen production was quantitatively determined by gas chromatography, and the results are as follows: Figure 8 As shown in (a), the performance of pure CIS in the photocatalytic hydrogen production process is clearly only 0.241 mmol / h. -1 g -1 The hydrogen production rate of CIS-Vs was 1.027 mmol h⁻¹. -1 g -1 The hydrogen production rate of the 5CC composite material obtained by loading Co3O4 onto pure CIS was 1.16 mmol / h. -1 g -1 However, the composites obtained by loading Co3O4 onto the modified CIS (CIS-Vs) showed significantly improved performance compared to 5CC. Among them, 5CC-Vs-30s exhibited the highest performance, at 10.378 mmol h⁻¹. -1 g -1The performance of the composite material was 43, 10, and 9 times that of CIS, CIS-Vs, and 5CC, respectively. Notably, the performance of the composite material improved with increasing vacancy concentration. However, after further increasing the sulfur vacancy concentration, the hydrogen production performance of 5CC-Vs-60s decreased compared to 5CC-Vs-30s, possibly due to structural collapse caused by excessively high concentrations. Furthermore, the cyclic testing results of the material were as follows... Figure 8 As shown in (b), the photocatalytic hydrogen production performance of 5CC-Vs-30 can still be maintained at 93% after five cycles.
[0043] The photocatalytic hydrogen evolution reaction mechanism of the sulfur vacancy Co3O4 / CdIn2S4-Vs (CC-Vs) composite material prepared by the preparation method provided above in this invention is as follows: Figure 9 Under visible light irradiation, electrons in the valence band (VB) of a CdIn2S4 semiconductor absorb photon energy and undergo interband transitions, exciting them to the conduction band (CB) and leaving photogenerated holes within the valence band, forming initial photogenerated electron-hole pairs. When Co3O4 nanostructures are loaded onto the surface of a CdIn2S4-Vs substrate through interface engineering, the tight contact formed at the heterojunction interface provides an efficient channel for carrier migration. Based on the semiconductor bandgap matching characteristics, CdIn2S4 valence band holes migrate rapidly to the Co3O4 valence band through the heterojunction interface driven by the potential difference. Simultaneously, photogenerated electrons from both Co3O4 and CdIn2S4 are captured by sulfur vacancies on the CdIn2S4 surface, accumulating on the CdIn2S4 surface and achieving spatial separation of photogenerated electrons and holes. Subsequently, photogenerated electrons accumulate on the CdIn2S4 surface and undergo a reduction reaction, reducing H2O to H2; photogenerated holes accumulate on Co3O4 and undergo an oxidation reaction with triethanolamine, generating oxides.
[0044] The embodiments of this application have been described above with reference to the accompanying drawings. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the core ideas of this application. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.
Claims
1. A method for preparing a sulfur vacancy Co3O4 / CdIn2S4-Vs composite material, characterized in that, Includes the following steps: CdIn2S4 nanomaterials were placed in H2O2 solution, stirred, washed, and dried to obtain CdIn2S4-Vs nanomaterials with S vacancies. Co3O4 and the CdIn2S4-Vs nanomaterials were placed in anhydrous ethanol, stirred, washed, and dried to obtain the sulfur vacancy Co3O4 / CdIn2S4-Vs composite material.
2. The preparation method according to claim 1, characterized in that, The concentration of the H2O2 solution is 5 M.
3. The preparation method according to claim 2, characterized in that, The CdIn2S4 nanomaterials were placed in an H2O2 solution and stirred for 10 s–60 s.
4. The preparation method according to claim 1, characterized in that, The mass ratio of the Co3O4 to the CdIn2S4-Vs nanomaterial is 3-7:93-97.
5. The preparation method according to claim 4, characterized in that, The preparation method of Co3O4 includes the following steps: Cobalt chloride and urea were dissolved in water and then heated to react at 90℃-100℃. After the reaction was completed, the mixture was cooled, centrifuged, washed, and dried to obtain the precursor material. The precursor material was placed in a muffle furnace and calcined at 350℃-400℃. After calcination, Co3O4 nanomaterials were obtained.
6. The preparation method according to claim 1, characterized in that, The preparation method of the CdIn2S4 nanomaterial includes the following steps: Nitric acid tetrahydrate and indium nitrate tetrahydrate were dissolved in water and sonicated to obtain a mixed solution. Thioacetamide is dissolved in water to obtain a thioacetamide solution; The mixed solution and the thioacetamide solution were mixed evenly, and then placed in a reaction vessel and heated at 90℃-100℃ for reaction. After the reaction was completed, the mixture was washed and dried to obtain the CdIn2S4 nanomaterial.
7. The preparation method according to claim 6, characterized in that, The molar ratio of nitric acid tetrahydrate, indium nitrate tetrahydrate, and thioacetamide is 1:2:
4.
8. A sulfur vacancy Co3O4 / CdIn2S4-Vs composite material, characterized in that, It is prepared by the preparation method according to any one of claims 1-7.
9. The application of the sulfur vacancy Co3O4 / CdIn2S4-Vs composite material according to claim 8 in photocatalytic hydrogen production.