Zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst and preparation method thereof
The preparation of zinc oxide-indium trioxide/graphite phase carbon nitride photocatalysts by self-sacrificing inorganic template method solves the problems of uneven distribution of ZnO and In2O3 on g-C3N4 surface and lattice mismatch, achieving efficient CO2 reduction to CO, simplifying the process and reducing costs, and making it suitable for industrial applications.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TIANJIN POLYTECHNIC UNIV
- Filing Date
- 2026-06-03
- Publication Date
- 2026-07-03
AI Technical Summary
In existing technologies, ZnO, g-C3N4, and In2O3 have problems such as high lattice mismatch, easy formation of defect states at the interface, uneven component distribution, and complex processes in the photocatalytic CO2 reduction to CO process, which limit the material performance and industrial application.
A self-sacrificing inorganic template method was adopted to generate a zinc oxide-indium trioxide/graphite phase carbon nitride photocatalyst during calcination using a ZnIn2S4 template. The ZnO-In2O3 heterojunction was constructed through in-situ synchronous condensation, which achieved uniform dispersion and close contact of components, reduced interface defects, and improved electron transport efficiency.
It significantly improves the CO selectivity and yield of photocatalysts, simplifies the preparation process, reduces costs, is suitable for large-scale production, and has good batch stability and photochemical stability.
Smart Images
Figure CN122321927A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of photocatalytic material synthesis technology, specifically to a zinc oxide-indium trioxide / graphite-phase carbon nitride photocatalyst and its preparation method. Background Technology
[0002] Photocatalytic reduction of carbon dioxide to carbon monoxide (CO2→CO) is an important pathway for achieving carbon resource recycling and clean energy conversion. Currently, graphitic carbon nitride (g-C3N4) is widely used as a non-metallic photocatalyst matrix for this reaction due to its suitable conduction band position (approximately -1.2 eV, matching the reduction potential of CO2→CO), good visible light response, excellent chemical stability, and readily available and inexpensive raw materials. To overcome its inherent defects such as high photogenerated carrier recombination rate, limited specific surface area, and insufficient CO2 adsorption and activation capacity, researchers generally adopt a heterojunction strategy, introducing metal oxides as co-catalysts to regulate band structure, promote charge separation, and provide active sites. Among them, zinc oxide (ZnO) is often chosen due to its high electron mobility and suitable valence band position; indium trioxide (In2O3) is favored because its surface is rich in oxygen vacancies, which can enhance the chemical adsorption and activation capacity of CO2 molecules, and its conduction band position (approximately -0.9 eV) has good matching potential with g-C3N4. Therefore, synergistic loading of ZnO and In2O3 onto the surface of g-C3N4 to form a ternary composite system has become a mainstream technical route for improving CO selectivity and yield. In existing technologies, such agents are mostly prepared by physical mixing, impregnation-calcination, or sol-gel methods. That is, ZnO, In2O3 nanoparticles and g-C3N4 matrix are first synthesized separately, and then the components are composited by mechanical mixing, solution impregnation, or hydrolysis and condensation of co-precursors, and finally the structure is integrated by high-temperature heat treatment.
[0003] However, the aforementioned conventional preparation methods still face unavoidable technical bottlenecks in practical applications: On the one hand, the high lattice mismatch between ZnO and g-C3N4 (approximately 12%) leads to the formation of numerous defect states at their interface, which become non-radiative recombination centers for photogenerated electrons, weakening the charge transfer efficiency across the interface; on the other hand, ZnO and In2O3 components are difficult to achieve atomic-level spatial synergistic distribution on the g-C3N4 surface, often exhibiting local agglomeration, uneven coating, or phase separation, resulting in incomplete bimetallic oxide heterostructures and loose interfacial contacts. This not only limits the synergistic effect between ZnO and In2O3 but also reduces the overall specific surface area and CO2 adsorption site density of the material. Furthermore, the complex multi-step synthesis and post-processing procedures, narrow parameter control windows, and poor batch-to-batch repeatability hinder stable output of material properties and large-scale preparation. These problems collectively restrict the improvement of the actual efficiency and industrial application of the ZnO-In2O3 / g-C3N4 ternary system in photocatalytic CO2 reduction to CO. Summary of the Invention
[0004] The technical problem to be solved by the present invention is to address the above-mentioned deficiencies in the prior art by providing a zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst and its preparation method. Based on the graphite phase carbon nitride structural unit, the zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst is prepared by a self-sacrificial inorganic template method. The photocatalyst exhibits good carbon reduction carbon monoxide ability under visible light irradiation. Furthermore, the self-sacrificial template method effectively achieves uniform dispersion of the ternary components and limits the grain size of ZnO, reducing its interface defects with g-C3N4, thereby effectively improving its electron transport efficiency and photocatalytic performance.
[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst is a dual heterostructure composed of graphite phase carbon nitride and zinc oxide and indium trioxide simultaneously immobilized on its surface in situ.
[0006] The present invention also provides a method for preparing a zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst, which is prepared by a self-sacrificing inorganic template method using a zinc indium sulfide (ZnIn2S4) template. Specifically, it is prepared by calcining to remove the template and simultaneously generating zinc oxide and indium trioxide.
[0007] Furthermore, the zinc indium sulfide (ZnIn2S4) template is prepared by dissolving indium chloride, zinc chloride, and thioacetamide (TAA) in deionized water, reacting them at a constant temperature of 75-85°C for 5-7 hours, and then washing, centrifuging, and drying.
[0008] Furthermore, the molar ratio of each element in indium chloride, zinc chloride and thioacetamide (TAA) is In:Zn:TAA = (1.8-4):1:(5-16.3), and its concentration range, calculated as indium chloride, is 0.07~0.1 mol / L.
[0009] Further, the preparation method of the zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst includes the following steps: (1) preparing a zinc indium sulfide (ZnIn2S4) template; (2) preparing a photocatalyst precursor powder: adding a certain amount of urea to the zinc indium sulfide (ZnIn2S4) template obtained in step (1), and mixing the two thoroughly to obtain a zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst precursor powder; (3) preparing a zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst: calcining the photocatalyst precursor powder obtained in step (2) at 500~750℃ for 5~8 hours to obtain a zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst.
[0010] Furthermore, in step (2), the mass ratio of zinc indium sulfide (ZnIn2S4) template to urea should be 1:(340-500), and the mixing time should be ≥30 min. Preferably, the mass ratio of zinc indium sulfide (ZnIn2S4) template to urea should be 1:340.
[0011] Furthermore, in step (2), before mixing, when the zinc indium sulfide ZnIn2S4 template clumps due to placement, it should be ground to 200-300 mesh before being mixed evenly with a certain amount of urea.
[0012] Furthermore, the heating rate of the calcination process in step (3) is ≤5℃ / min.
[0013] Furthermore, the zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst prepared by the method described in this invention is suitable for visible light-catalyzed carbon dioxide reduction reactions.
[0014] The beneficial effects of this invention are as follows: This invention uses ZnIn2S4 as a self-sacrificing template and employs an integrated process of "template confinement-in-situ oxidation-synchronous polycondensation" to simultaneously construct ZnO-In2O3 heterojunctions during the pyrolysis forming of g-C3N4. This fundamentally avoids the problems of uneven component distribution, loose interfacial contact, and defect states caused by lattice mismatch resulting from traditional physical mixing or stepwise loading methods. During calcination, the ZnIn2S4 template undergoes controlled sulfur removal and metal oxidation. Its original layered structure induces the formation of a closely contacting heterogeneous interface between ZnO and In2O3 at the nanoscale, significantly reducing the probability of interfacial electron capture. Simultaneously, ZnO (CB≈-0.3eV), In2O3 (CB≈-0.9eV), and g-C3N4 (CB≈-1.2eV) form a stepped conduction band arrangement, driving photogenerated electrons to migrate directionally from g-C3N4 to In2O3 and then to ZnO, greatly extending the carrier lifetime. The surface of In2O3 is rich in oxygen vacancies, effectively enhancing the chemical adsorption of CO2 molecules and the activation of C=O bonds, while ZnO provides a fast electron transport channel. The two work synergistically to enhance the selectivity and kinetic efficiency of the CO2→CO two-electron reduction pathway.
[0015] The above preparation method can obtain a photocatalyst with uniform composition of zinc oxide-indium trioxide / graphite phase carbon nitride without hydrothermal reaction and multi-step sol-gel method. Moreover, the method is simple, easy to operate, uses readily available raw materials, does not require complicated equipment, and has low production cost. It is very suitable for large-scale industrial production and has good batch stability and large-scale scale-up potential.
[0016] Experiments show that the photocatalyst material prepared by the above method achieves a CO yield of 80 μmol·g under visible light. -1XRD and HRTEM confirmed that its crystal structure and interface morphology are highly stable, and it has excellent photochemical stability and photocatalytic stability, providing a new paradigm that combines scientific validity and engineering feasibility for promoting the practical application of photocatalytic carbon resource utilization. Attached Figure Description
[0017] Figure 1 Scanning electron microscope (SEM) image of the photocatalyst prepared in Example 1; Figure 2 Transmission electron microscopy (HRTEM) image of the photocatalyst prepared in Example 1; Figure 3 X-ray diffraction (XRD) pattern of the photocatalyst prepared in Example 1; Figure 4 A bar chart comparing the CO yield of the photocatalyst prepared in Example 1 with other different samples (horizontal comparison of the upper limit of the activity of different catalysts). Figure 5 Comparison of CO yield curves for photocatalysts prepared in Examples 1-3 (vertical verification of the stability of the target catalyst and process repeatability); Figure 6 Comparison of CO yield of photocatalysts prepared in Comparative Examples 1 and 2 with those prepared in Example 1; Figure 7 Scanning electron microscope (SEM) image of the photocatalyst prepared in Comparative Example 1; Figure 8 Scanning electron microscope (SEM) image of the photocatalyst prepared in Comparative Example 2. Detailed Implementation
[0018] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.
[0019] Example 1 A zinc oxide-indium trioxide / graphite-phase carbon nitride photocatalyst, the specific preparation steps are as follows: 1) Preparation of zinc indium sulfide (ZnIn2S4) template: 0.597g indium chloride, 0.136g zinc chloride, and 0.601g TAA were dissolved in 30ml deionized water and kept in an 80℃ water bath for 6 hours. The precipitate was collected, washed with anhydrous ethanol and deionized water respectively, and centrifuged and dried at 3000rpm to obtain the ZnIn2S4 template (ZIS template for short). 2) Preparation of precursor powder for zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst: 0.05g ZnIn2S4 template and 17g urea were ground and then mixed uniformly for 40 minutes using a powder mixer to obtain zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst precursor powder. 3) Preparation of zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst: The zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst precursor powder obtained in step 2) was placed in a muffle furnace and calcined at a rate of 5°C per minute to 550°C and held for 6 hours to obtain the zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst.
[0020] The microstructure of the photocatalyst composite sample prepared in Example 1 was characterized as follows: its scanning electron microscope (SEM) image is shown below. Figure 1 As shown, the sample prepared in Example 1 has a sheet-like / layered interwoven structure, providing a large specific surface area, which is beneficial for light absorption and reactant adsorption; transmission electron microscopy (HRTEM) results are as follows. Figure 2 As shown in the figure, the coexistence of In2O3-(222) and ZnO-(100) lattice fringes can be observed, proving that ZnO and In2O3 form a closely contacted heterojunction interface in the g-C3N4 matrix, providing a channel for the separation and transport of photogenerated charges.
[0021] X-ray diffraction (XRD) pattern as shown Figure 3 As shown, the left figure shows that the composite sample contains characteristic peaks of both In2O3 and ZnO, indicating that these two crystal phases were successfully introduced into the composite sample (without obvious impurities); the right figure shows that CN in the composite sample also retains its characteristic (002) layered structure, indicating that the three materials formed the heterojunction composite material of the present invention through in-situ growth: zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst.
[0022] The photocatalytic performance of the photocatalyst composite sample prepared in Example 1 was tested: The photocatalytic reaction was carried out in an open reactor with a diameter of 90 mm, and the reactor was placed in a circulating water bath to maintain the photocatalytic reaction temperature at approximately 25°C. A 300W xenon lamp was used as the light source, and a 400nm filter was used to obtain visible light with wavelengths greater than 400nm. The vertical distance between the light source and the liquid surface in the reactor was approximately 25 cm. 5 mg of the zinc oxide-indium trioxide / graphite-phase carbon nitride sample prepared in Example 1 was placed in the reactor, and carbon dioxide was introduced to simulate an industrial carbon reduction environment. Gas was extracted from the container every hour for gas chromatography analysis to determine the CO content, and the yield was calculated for comparison with other types of photocatalysts. Figure 4As shown, it can be seen that CN / ZnO+In2O3 (geminate-co-supported) has the highest CO yield (close to 80 after 3 hours), which is much higher than that of pure CN, CN / ZnO and other samples; indicating that the photocatalyst composite sample prepared in Example 1 has the best performance in photocatalytic reduction of CO2.
[0023] Example 2 A zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst is prepared by the following steps: 1) Preparation of zinc indium sulfide (ZIS) template: 0.774 g indium chloride, 0.245 g zinc chloride, and 1.225 g TAA are dissolved in 35 ml of deionized water and reacted at 75 °C for 5 hours. The precipitate is collected, washed with anhydrous ethanol and deionized water respectively, and dried by centrifugation at 8000 rpm to obtain the ZIS template.
[0024] 2) Preparation of precursor powder for zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst: 0.05g ZnIn2S4 template and 25g urea were ground and then mixed uniformly for 30min using a powder mixer to obtain precursor powder for zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst.
[0025] 3) Preparation of zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst: The zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst precursor powder obtained in step 2) is placed in a muffle furnace and heated to 750°C at a rate of 5 degrees per minute and held for 5 hours to obtain the zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst.
[0026] The photocatalytic performance of the composite photocatalytic material prepared in this example was tested using the same method as in Example 1. The results were compared with those of Example 1. Figure 5 As shown.
[0027] Example 3 The preparation steps of the zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst are as follows: 1) Preparation of zinc indium sulfide (ZIS) template: 0.442 g indium chloride, 0.068 g zinc chloride and 0.375 g TAA were dissolved in 25 ml of deionized water and reacted at 85 °C for 5 hours. The precipitate was collected, washed with anhydrous ethanol and deionized water respectively, and dried by centrifugation at 2500 rpm to obtain the ZIS template.
[0028] 2) Preparation of precursor powder for zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst: 0.09g ZnIn2S4 template and 36g urea were ground and then mixed uniformly for 35min using a powder mixer to obtain precursor powder for zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst.
[0029] 3) Preparation of zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst: The zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst precursor powder obtained in step 2) was placed in a muffle furnace and heated to 520°C at a rate of 5°C per minute and held for 7 hours to obtain the zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst.
[0030] The photocatalytic performance of the composite photocatalytic material prepared in this example was tested using the same method as in Example 1. The results were compared with those of Example 1. Figure 5 As shown.
[0031] In Examples 1, 2, and 3, CO2 production showed a very stable linear growth trend over a 2-hour testing period, with the final yield reaching approximately 50 µmol·g. -1 The CO yield is around 100%, indicating that the catalyst exhibits good stability and continuous gas production under light irradiation. However, under a pure nitrogen (In N2) atmosphere (without CO2), the CO yield is extremely low, indicating that the carbon source for the CO product does indeed originate from the carbon source introduced into the reaction system (usually CO2 gas), eliminating interference from the decomposition of carbonaceous materials within the catalyst itself. Under dark conditions, the CO yield is 0, directly proving that the reaction is entirely driven by light energy, constituting a purely photocatalytic process. In summary, Figure 4 and 5 From the perspectives of "horizontal performance comparison" and "vertical stability verification", the excellent performance and process reliability of the zinc oxide-indium trioxide / graphite phase carbon nitride (ZnO-In2O3 / g-C3N4) photocatalyst system were fully demonstrated, providing a solid experimental basis for its subsequent application.
[0032] Comparative Example 1 A zinc oxide-indium trioxide / graphite-phase carbon nitride photocatalyst was prepared using the same steps as in Example 1, except that in step 2), the ZnIn2S4 template to urea was added in a mass ratio of 1:666.7. The prepared zinc oxide-indium trioxide / graphite-phase carbon nitride photocatalyst was characterized structurally, and its performance was tested as follows: Figure 7 and 6 As shown.
[0033] The results showed that the performance of the photocatalyst sample was lower than that of the sample prepared in Example 1.
[0034] Comparative Example 2 A zinc oxide-indium trioxide / graphite-phase carbon nitride photocatalyst was prepared using the same steps as in Example 1, except that in step 2), the ZnIn2S4 template to urea was added in a mass ratio of 1:285.7. The prepared zinc oxide-indium trioxide / graphite-phase carbon nitride photocatalyst was characterized structurally, and its performance was tested as follows: Figure 8 and 6 As shown.
[0035] The results showed that the performance of the photocatalyst sample was lower than that of the sample prepared in Example 1.
[0036] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.
Claims
1. A zinc oxide-indium trioxide / graphite-phase carbon nitride photocatalyst, characterized in that, It is a dual heterostructure consisting of graphitic carbon nitride and zinc oxide and indium trioxide synchronously immobilized on its surface in situ.
2. A method for preparing a zinc oxide-indium trioxide / graphite-phase carbon nitride photocatalyst, characterized in that, It is prepared by a self-sacrificing inorganic template method using a zinc indium sulfide (ZnIn2S4) template.
3. The preparation method of the zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst according to claim 2, characterized in that, The zinc indium sulfide (ZnIn2S4) template is prepared by dissolving indium chloride, zinc chloride, and thioacetamide (TAA) in deionized water, reacting them at a constant temperature of 75-85°C for 5-7 hours, and then washing, centrifuging, and drying.
4. The preparation method of the zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst according to claim 3, characterized in that, The molar ratio of each element in indium chloride, zinc chloride and thioacetamide (TAA) is In:Zn:TAA = (1.8-4):1:(5-16.3), and the concentration range of indium chloride is 0.07~0.1 mol / L.
5. The preparation method of the zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst according to claim 3, characterized in that, Includes the following steps: (1) Preparation of the zinc indium sulfide ZnIn2S4 template; (2) Preparation of photocatalyst precursor powder: A certain amount of urea is added to the zinc indium sulfide ZnIn2S4 template obtained in step (1), and the two are thoroughly mixed to obtain zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst precursor powder. (3) Preparation of zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst: The photocatalyst precursor powder obtained in step (2) is calcined at 500~750℃ for 5~8 hours to obtain zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst.
6. The preparation method of the zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst according to claim 5, characterized in that, In step (2), the mass ratio of zinc indium sulfide (ZnIn2S4) template to urea should be 1:(340-500), and the time for them to be mixed evenly should be ≥30 min.
7. The preparation method of the zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst according to claim 5, characterized in that, In step (2), the mass ratio of zinc indium sulfide (ZnIn2S4) template to urea should be 1:340, and the time for them to be mixed evenly should be ≥30 min.
8. The preparation method of the zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst according to claim 5, characterized in that, Before mixing in step (2), when the zinc indium sulfide ZnIn2S4 template clumps due to placement, it should be ground to 200-300 mesh before being mixed evenly with a certain amount of urea.
9. The preparation method of the zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst according to claim 5, characterized in that, The heating rate of the calcination process in step (3) is ≤5℃ / min.
10. Use of the zinc oxide-indium trioxide / graphite phase carbon nitride photocatalyst prepared by the method according to any one of claims 3 to 9 in visible light catalytic carbon dioxide reduction reaction.