Amorphous molybdenum sulfide loaded oxygen-doped graphite phase carbon nitride catalyst as well as preparation method and application thereof
By combining amorphous molybdenum sulfide with oxygen-doped graphitic carbon nitride, the problems of photogenerated electron-hole pair recombination and small specific surface area in photocatalysts were solved, achieving efficient and stable photocatalytic hydrogen production.
Patent Information
- Application Number
- CN202411111599.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-14
- Publication Date
- 2026-03-03
AI Technical Summary
Existing photocatalysts, such as graphitic carbon nitride (g-C3N4), suffer from severe recombination of photogenerated electron-hole pairs, small specific surface area, high production cost, and scarcity of raw materials, which affect their photocatalytic hydrogen production efficiency.
By loading amorphous molybdenum sulfide (a-MoSx) and combining it with oxygen-doped graphitic carbon nitride (O-C3N4), [Mo2S12]2- nanoclusters are converted into a-MoSx using impregnation and in-situ pyrolysis techniques, forming a tightly bound catalyst.
It improves the hydrogen production activity and stability of photocatalysts, reduces production costs, expands the light absorption range, enhances interfacial active sites, and reduces electron recombination.
Smart Images
Figure CN121588869A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of inorganic functional material preparation technology, specifically to an amorphous molybdenum sulfide-supported oxygen-doped graphite-phase carbon nitride catalyst, its preparation method, and its application. Background Technology
[0002] Given the world's heavy reliance on non-renewable energy sources such as coal and natural gas, coupled with the volatile price of crude oil, it is imperative to strengthen the development and utilization of clean, green, and renewable energy sources to replace traditional fossil fuels. Hydrogen energy, with its advantages of being clean, non-toxic, and having a higher energy density than other natural resources, is hailed as the "energy of the future." Using semiconductor photocatalysis to split water and obtain hydrogen is a green and environmentally friendly method; however, the hydrogen production rate and energy utilization efficiency have become barriers to its industrial application. Therefore, finding inexpensive, stable, readily available, and highly efficient photocatalysts has become paramount.
[0003] Graphitic carbon nitride (g-C3N4) has been widely studied in the field of photocatalysis due to its easy synthesis, unique band structure, and high physicochemical stability. However, g-C3N4 also faces a series of problems: photogenerated electron-hole pairs exhibit a strong recombination tendency during migration and at the semiconductor surface, leading to energy dissipation in the form of heat and light radiation; g-C3N4 has a relatively small specific surface area, meaning that the amount of H2 adsorption that a unit mass of photocatalyst can provide is limited. + The limited number of active sites for hydrogen production through reduction contributes to the unsatisfactory photocatalytic hydrogen production performance of pure-phase g-C3N4. Oxygen doping of g-C3N4 can be achieved through repeated calcination. After O doping, the band gap of g-C3N4 decreases, and simultaneously, the electron density of the C atoms closest to the O-doped atoms decreases sharply, while the electron density of the nearest N atoms increases sharply, generating an internal electric field conducive to electron-hole separation.
[0004] Loading co-catalysts onto the surface of photocatalysts is another effective strategy to enhance photocatalytic activity. Although noble metal co-catalysts, represented by Pt, exhibit excellent performance, their high price and resource scarcity are key bottlenecks restricting their application in photocatalysis. Molecular nanoclusters [Mo2S] 12 ] 2- Typically formed under liquid-phase conditions by exchanging ligands between oxymolybdates and sulfur-containing reagents (such as hydrogen sulfide and thioacetamide), it possesses abundant unsaturated sulfur active sites at its edge positions, enabling it to adsorb more protons from the solution. These protons then combine with photogenerated electrons generated by the semiconductor to reduce the protons to H2, demonstrating significant potential in photocatalytic hydrogen evolution. [Mo2S] 12 ] 2- In comparison, amorphous molybdenum sulfide a-MoS xDue to the diversity of atomic arrangement and the large number of defect sites, which result in more interfacial active sites, the amorphization transformation of nanoclusters can achieve better hydrogen production.
[0005] Due to [Mo2S] 12 ] 2- Since it lacks an independent semiconductor band structure for photocatalysis, its application in photocatalysis inevitably relies on a photocatalyst host. This means that in heterogeneous suspended photocatalytic systems, achieving amorphization beyond the assembly of nanoclusters and the photocatalyst host is crucial for improving the [Mo2S] content. 12 ] 2- The photocatalytic hydrogen production activity of composite materials is a problem that urgently needs to be solved. Summary of the Invention
[0006] This invention provides an amorphous molybdenum sulfide-supported oxygen-doped graphite-phase carbon nitride catalyst, its preparation method, and its application, overcoming the shortcomings of the prior art. It can effectively solve the problems of high production cost, scarce raw materials, and low hydrogen production activity of existing photocatalysts.
[0007] One of the technical solutions of this invention is achieved through the following measures: a method for preparing an amorphous molybdenum sulfide-supported oxygen-doped graphite-phase carbon nitride catalyst, comprising the following steps: The first step is to calcine the required amount of precursor urea to obtain g-C3N4, which is graphitic carbon nitride. The second step is to recalculate g-C3N4 in an oxygen stream to obtain O-C3N4, which is oxygen-doped graphitic carbon nitride. The third step is to synthesize (NH4)2Mo2S. 12 ·2H2O; The fourth step involves impregnating (NH4)2Mo2S with water. 12 ·2H2O loaded on O-C3N4 yields Mo2S 12 / O-C3N4, i.e. [Mo2S 12 ] 2- Nanoclusters loaded with oxygen-doped graphitic carbon nitride; The fifth step involves using in-situ pyrolysis to decompose Mo2S. 12 / O-C3N4 was calcined in an argon gas stream to obtain α-MoS x / O-C3N4 refers to an amorphous molybdenum sulfide-supported oxygen-doped graphite-phase carbon nitride catalyst.
[0008] The following are further optimizations and / or improvements to one of the above-mentioned technical solutions: In the first step above, the calcination temperature is 540℃ to 560℃, the heating rate is 5℃ / min, and the holding time is 3.5h to 4.5h.
[0009] In the second step above, the reheating temperature is 540℃ to 560℃, the heating rate is 2℃ / min, and the holding time is 1.5h to 2.5h.
[0010] In the third step above, (NH4)2Mo2S 12 The synthesis of 2H2O is carried out according to the following steps: S1, 30 mL of (NH4)2S was mixed with 7.1 g of sulfur powder and stirred at 50 °C for 15 min to obtain (NH4)2S. x Solution; S2, 2g of ammonium molybdate tetrahydrate and 1.5g of hydroxylamine hydrochloride were mixed to prepare the first mixture; S3, mix 30 mL of the first mixture with (NH4)2S x The solutions were mixed and stirred at 50°C for 2 hours. After filtration, the filtrate was obtained. S4, the filtrate was stirred at 90℃ for 4 hours and cooled to room temperature, and then mixed with 20 mL of (NH4)2S and 6 g of sulfur powder to obtain the second mixture; S5, the second mixture was stirred in an argon atmosphere for 12 hours, filtered, washed sequentially with a low-temperature detergent and centrifuged, and then vacuum dried for 12 hours to obtain (NH4)2Mo2S. 12 ·2H2O.
[0011] In step S5 above, the low-temperature detergent is 10 mL of deionized water, 10 mL of ethanol, 10 mL of carbon disulfide, and 20 mL of diethyl ether at 4°C.
[0012] In the fourth step above, the specific process of impregnation is as follows: (NH4)2Mo2S 12 ·2H2O was dissolved in methanol, O-C3N4 was added, and the mixture was ultrasonically dispersed for 30 min, then magnetically stirred for 4 h, and centrifuged and vacuum dried for 12 h to obtain Mo2S. 12 / O-C3N4.
[0013] The above (NH4)2Mo2S 12 The impregnation mass fraction of 2H2O is 1% to 10%.
[0014] In the fifth step above, the calcination temperature is 180℃, the calcination time is 2h, and the heating rate is 2℃ / min.
[0015] The second technical solution of the present invention is achieved by the following measures: an amorphous molybdenum sulfide supported oxygen-doped graphite phase carbon nitride catalyst obtained by the above preparation method.
[0016] The third technical solution of the present invention is achieved through the following measures: the application of an amorphous molybdenum sulfide-supported oxygen-doped graphite phase carbon nitride catalyst in photocatalytic hydrogen production.
[0017] This invention is the first to use an impregnation method to [Mo2S] 12 ] 2- Nanoclusters were loaded onto graphitic carbon nitride and [Mo2S] were transferred via in-situ pyrolysis. 12 ] 2- In-situ transformation of nanoclusters into amorphous molybdenum sulfide α-MoS x , a-MoS x It is tightly bonded to graphitic carbon nitride and can be used for photocatalytic hydrogen production, which greatly improves the hydrogen production activity of the photocatalyst and makes the hydrogen evolution performance sufficiently stable. Attached Figure Description
[0018] Appendix Figure 1 The 4wt% Mo2S in Examples 12 and 15 of this invention 12 -180 / O-C3N4, 10wt% Mo2S 12 -180 / O-C3N4, support O-C3N4, (NH4)2Mo2S 12 ·2H2O and the pyrolysis of Mo2S 12 XRD pattern at -180°; Appendix Figure 2 The 10wt% Mo2S in Example 15 of this invention 12 SEM and TEM images of -180 / O-C3N4; Appendix Figure 3 The 10wt% Mo2S before pyrolysis in Example 15 of this invention 12 / O-C3N4 and 10wt% Mo2S after pyrolysis 12 XPS spectrum of -180 / O-C3N4; Appendix Figure 4 The 10wt% Mo2S in Example 15 of this invention 12 UV-Vis comparison chart of -180 / O-C3N4 and O-C3N4; Appendix Figure 5 The 10wt% Mo2S in Example 15 of this invention 12 Comparison of bandgap widths between -180 / O-C3N4 and O-C3N4; Appendix Figure 6 The 4wt% Mo2S in Example 12 of this invention 12 Circular hydrogen production performance of -180 / O-C3N4; Appendix Figure 7 The 4wt% Mo2S before pyrolysis in Example 12 of this invention12 / O-C3N4 cyclic hydrogen production performance diagram; Appendix Figure 8 The α-MoS obtained in Examples 11 to 15 of this invention x Hydrogen production performance diagram of / O-C3N4. Detailed Implementation
[0019] This invention is not limited to the following embodiments, and specific implementation methods can be determined according to the technical solutions and actual conditions of this invention. Unless otherwise specified, all chemical reagents and chemicals mentioned in this invention are well-known and commonly used chemical reagents and chemicals in the prior art; unless otherwise specified, all percentages in this invention are mass percentages; unless otherwise specified, all solutions in this invention are aqueous solutions with water as the solvent, for example, hydrochloric acid solution is an aqueous solution of hydrochloric acid; room temperature in this invention generally refers to a temperature between 15°C and 25°C, generally defined as 25°C.
[0020] The present invention will be further described below with reference to embodiments: Example 1: The preparation method of this amorphous molybdenum sulfide-supported oxygen-doped graphite-phase carbon nitride catalyst is carried out according to the following steps: The first step is to calcine the required amount of precursor urea to obtain g-C3N4, which is graphitic carbon nitride. The second step is to recalculate g-C3N4 in an oxygen stream to obtain O-C3N4, which is oxygen-doped graphitic carbon nitride. The third step is to synthesize (NH4)2Mo2S. 12 ·2H2O; The fourth step involves impregnating (NH4)2Mo2S with water. 12 ·2H2O loaded on O-C3N4 yields Mo2S 12 / O-C3N4, i.e. [Mo2S 12 ] 2- Nanoclusters loaded with oxygen-doped graphitic carbon nitride; The fifth step involves using in-situ pyrolysis to decompose Mo2S. 12 / O-C3N4 was calcined in an argon gas stream to obtain α-MoS x / O-C3N4 refers to an amorphous molybdenum sulfide-supported oxygen-doped graphite-phase carbon nitride catalyst.
[0021] This invention first obtains oxygen-doped graphitic carbon nitride through high-temperature thermal polymerization and oxygen etching, and then uses an impregnation method to [Mo2S] 12 ] 2- Nanoclusters were loaded onto oxygen-doped graphitic carbon nitride, and finally [Mo2S] was released through in-situ pyrolysis. 12 ] 2-Nanoclusters are transformed into amorphous molybdenum sulfide to obtain an amorphous molybdenum sulfide-supported oxygen-doped graphitic carbon nitride catalyst.
[0022] Example 2: As an optimization of the above example, in the first step, the calcination temperature is 540℃ to 560℃, the heating rate is 5℃ / min, and the holding time is 3.5h to 4.5h.
[0023] Example 3: As an optimization of the above example, in the second step, the reheating temperature is 540℃ to 560℃, the heating rate is 2℃ / min, and the holding time is 1.5h to 2.5h.
[0024] Example 4: As an optimization of the above examples, in the third step, (NH4)2Mo2S 12 The synthesis of 2H2O is carried out according to the following steps: S1, 30 mL of (NH4)2S was mixed with 7.1 g of sulfur powder and stirred at 50 °C for 15 min to obtain (NH4)2S. x Solution; S2, 2g of ammonium molybdate tetrahydrate and 1.5g of hydroxylamine hydrochloride were mixed to prepare the first mixture; S3, mix 30 mL of the first mixture with (NH4)2S x The solutions were mixed and stirred at 50°C for 2 hours. After filtration, the filtrate was obtained. S4, the filtrate was stirred at 90℃ for 4 hours and cooled to room temperature, and then mixed with 20 mL of (NH4)2S and 6 g of sulfur powder to obtain the second mixture; S5, the second mixture was stirred in an argon atmosphere for 12 hours, filtered, washed sequentially with a low-temperature detergent and centrifuged, and then vacuum dried for 12 hours to obtain (NH4)2Mo2S. 12 ·2H2O.
[0025] Example 5: As an optimization of the above example, in step S5, the low-temperature detergent is 10 mL of deionized water, 10 mL of ethanol, 10 mL of carbon disulfide and 20 mL of diethyl ether at 4°C.
[0026] Example 6: As an optimization of the above embodiment, in the fourth step, the specific process of impregnation is as follows: (NH4)2Mo2S 12 ·2H2O was dissolved in methanol, O-C3N4 was added, and the mixture was ultrasonically dispersed for 30 min, then magnetically stirred for 4 h, and centrifuged and vacuum dried for 12 h to obtain Mo2S. 12 / O-C3N4.
[0027] Example 7: As an optimization of the above examples, (NH4)2Mo2S 12 The impregnation mass fraction of 2H2O is 1% to 10%, i.e., (NH4)2Mo2S12 The mass fraction of 2H2O in O-C3N4 is 1% to 10%, which is the result of Mo2S. 12 In / O-C3N4, Mo2S 12 The loading rate is 1wt% to 10wt%.
[0028] Example 8: As an optimization of the above example, in the fifth step, the calcination temperature is 180℃, the calcination time is 2h, and the heating rate is 2℃ / min.
[0029] Example 9: The amorphous molybdenum sulfide supported oxygen-doped graphite phase carbon nitride catalyst obtained by the above preparation method.
[0030] Example 10: Application of the amorphous molybdenum sulfide-supported oxygen-doped graphite phase carbon nitride catalyst in photocatalytic hydrogen production.
[0031] Traditional amorphous a-MoS x The precursors for synthesis are mostly MoS4 2- In situ, amorphous α-MoS₂ is transformed through photodeposition or electrodeposition. x In this invention, the nanoclusters [Mo2S] 12 ] 2- and [Mo3S] 13 ] 2- Compared to MoS4 2- Individual anions possess more unsaturated S atoms, and the adsorption hydrogen Gibbs free energy of the nano-molybdenum-sulfur clusters themselves is highly suitable for photocatalytic HER, making them excellent amorphous a-MoS₂ clusters. x Synthetic precursors. However, currently, there are no amorphous α-MoS₂ with clustered evolution in the field of photocatalysis. x The amorphous molybdenum sulfide-supported oxygen-doped graphite-phase carbon nitride catalyst of this invention can be applied to photocatalytic hydrogen production, thus improving the [Mo2S] content. 12 ] 2- Photocatalytic hydrogen production activity of composite materials.
[0032] Example 11: The amorphous molybdenum sulfide-supported oxygen-doped graphite-phase carbon nitride catalyst was prepared according to the following method: The first step is to place 15g of urea in a 100mL covered quartz crucible and calcine it in a muffle furnace at a temperature of 550℃ for 4 hours with a heating rate of 5℃ / min to obtain g-C3N4 (i.e., graphitic carbon nitride). The second step is to grind the obtained g-C3N4 into powder, spread the powder evenly in a ceramic boat, place it in a tube furnace, and calcine it in an oxygen flow. The calcination temperature is 550℃, the holding temperature is 2 h, and the heating rate is 2℃ / min to obtain O-C3N4 (i.e. oxygen-doped graphitic carbon nitride). The third step involves mixing 30 mL of (NH4)2S with 7.1 g of sulfur powder and stirring at 50 °C for 15 min to obtain (NH4)2S. x The solution was prepared by mixing 2 g of ammonium molybdate tetrahydrate and 1.5 g of hydroxylamine hydrochloride to obtain the first mixture. 30 mL of the first mixture was then mixed with the above (NH4)2S solution. x The solutions were mixed and stirred at 50°C for 2 hours, then filtered. The filtrate was stirred at 90°C for 4 hours, cooled to room temperature, and then mixed with 20 mL of (NH4)2S and 6 g of sulfur powder. The mixture was stirred overnight for 12 hours under an argon atmosphere, filtered, and washed successively with 10 mL of deionized water, 10 mL of ethanol, 10 mL of carbon disulfide, and 20 mL of diethyl ether at 4°C. After centrifugation, the mixture was vacuum dried for 12 hours to obtain nanoclusters of (NH4)2Mo2S. 12 ·2H2O; The fourth step involves adding a certain mass of nanoclusters of (NH4)2Mo2S. 12 ·2H2O was dissolved in 40mL of methanol, 50mg of O-C3N4 was added, and the mixture was ultrasonically dispersed for 30min, then magnetically stirred for 4h, centrifuged, and vacuum dried for 12h to obtain (NH4)2Mo2S. 12 • 2H₂O accounts for 1% of the mass fraction of O-C₃N₄, yielding Mo₂S. 12 / O-C3N4, recorded as 1wt% Mo2S 12 / O-C3N4; Step 5, add 1wt% Mo2S 12 / O-C3N4 was placed in a tube furnace and calcined at 180℃ for 2 hours in an argon atmosphere with a heating rate of 2℃ / min to obtain MoS2. 12 -180 / O-C3N4, this sample is recorded as 1wt% Mo2S 12 -180 / O-C3N4, in which molybdate undergoes in-situ pyrolysis to form amorphous molybdenum sulfide α-MoS2. 12 (i.e., nanoclusters of Mo2S) 12 -180).
[0033] Example 12: The preparation method is the same as that in Example 11, except that (NH4)2Mo2S in the fourth step... 12 The mass fraction of 2H₂O in O-C₃N₄ is 4%, and the α-MoS₂ obtained in step 5... x / O-C3N4, this sample is recorded as 4wt% Mo2S 12 -180 / O-C3N4.
[0034] Example 13: The preparation method is the same as that in Example 11, except that (NH4)2Mo2S is used in the fourth step. 12The mass fraction of 2H₂O in O-C₃N₄ is 6%, and the α-MoS₂ obtained in step 5... x / O-C3N4, this sample was recorded as 6wt% Mo2S 12 -180 / O-C3N4.
[0035] Example 14: The preparation method is the same as that in Example 11, except that (NH4)2Mo2S is used in the fourth step. 12 ·2H2O accounts for 8% of the mass fraction of O-C3N4, and the α-MoS obtained in step 5 x / O-C3N4, this sample is recorded as 8wt% Mo2S 12 -180 / O-C3N4.
[0036] Example 15: The preparation method is the same as that in Example 11, except that (NH4)2Mo2S in the fourth step... 12 ·2H2O accounts for 10% of the mass fraction of O-C3N4, and the α-MoS obtained in step 5 x / O-C3N4, this sample is recorded as 10wt% Mo2S 12 -180 / O-C3N4.
[0037] According to Embodiments 12 and 15 of the present invention, 4wt% Mo2S 12 -180 / O-C3N4, 10wt% Mo2S 12 -180 / O-C3N4, support O-C3N4, (NH4)2Mo2S 12 ·2H2O and the pyrolysis of Mo2S 12 XRD pattern of -180 as follows Figure 1 As shown. By Figure 1 It can be seen that (NH4)2Mo2S 12 After pyrolysis of 2H2O at 180℃, the original characteristic peaks basically disappeared, while a new broad peak appeared at around 2θ=14°, indicating that the powder transformed into amorphous molybdenum sulfide α-MoS2. x At a lower load of 4wt%, [Mo2S] is reduced due to the lower load. 12 ] 2- The diffraction peak intensity is weak, indicating that the composite sample Mo2S 12 / Both before and after pyrolysis, O-C3N4 exhibited characteristic diffraction peaks characteristic of the O-C3N4 support. Higher loadings of 10wt% Mo2S... 12 In addition to the characteristic peaks of O-C3N4, [Mo2S] also appeared in -180 / O-C3N4 before and after calcination. 12 ] 2- The diffraction peaks of the crystal and [Mo2S] at 180℃ 12 ]2- The broad peaks corresponding to the pyrolysis products indicate that the combined method of impregnation and pyrolysis can achieve [Mo2S]. 12 ] 2- The load and its in-situ conversion to a-MoS x And [Mo2S] 12 ] 2- The pyrolysis process does not affect the crystal structure of the photocatalyst.
[0038] 10wt% Mo2S in Example 15 of the present invention 12 SEM images of -180 / O-C3N4 are as follows Figure 2 As shown in (d), the TEM image is as follows: Figure 2 -(f) is shown. By Figure 2 -(d) indicates that amorphous molybdenum sulfide a-MoS x The particles, ranging in size from 200 nm to 300 nm, are embedded in the porous, sheet-like structure of O-C3N4, rather than being a uniform load of ultra-small nanoparticles; Figure 2 From (f), we can see that a-MoS x The [Mo2S] crystals are tightly grown on or encapsulated within O-C3N4, and no lattice fringes are observed at higher magnification, indicating that the [Mo2S] crystals after pyrolysis... 12 ] 2- Composite in an amorphous manner.
[0039] 10wt% Mo2S before pyrolysis in Example 15 of this invention 12 / O-C3N4 and 10wt% Mo2S after pyrolysis 12 The XPS spectrum of -180 / O-C3N4 is shown in Figure 3. Figure 3 -b indicates that the S2p spectrum of the pyrolyzed composite sample shows a new SO peak at a higher binding energy; from Figure 3 -c、 Figure 3 As can be seen from -d, after calcination, there is a SO peak near the C=O peak that is not present in the sample before calcination, indicating that [Mo2S] 12 ] 2- a-MoS formed after in-situ pyrolysis x The catalyst interacts with the abundant O element in O-C3N4 through chemical bonds, thus enabling the catalyst to be stably and firmly bonded to the bulk.
[0040] In Example 15 of this invention, 10 wt% Mo2S 12 The UV-Vis comparison chart of -180 / O-C3N4 and O-C3N4 is shown below. Figure 4 As shown. By Figure 4It can be seen that the light absorption range of O-C3N4 is mainly concentrated in the ultraviolet light band, while that of 10wt% Mo2S... 12 -180 / O-C3N4 also exhibited a certain absorption intensity in the visible light band, indicating that the loaded α-MoS2 x It expands the light absorption range to a certain extent.
[0041] In Example 15 of this invention, 10 wt% Mo2S 12 The bandgap comparison chart of -180 / O-C3N4 and O-C3N4 is shown in the figure below. Figure 5 It can be seen that, compared to the O-C3N4 support, 10wt% Mo2S 12 The absorption edge of -180 / O-C3N4 exhibits a red shift, with the corresponding bandgap shrinking from 2.99 eV to 2.94 eV, indicating that the loading a-MoS2... x The band structure was improved.
[0042] In Example 12 of this invention, 4wt% Mo2S 12 The cyclic hydrogen production performance of -180 / O-C3N4 is shown in the figure below. Figure 6 As shown. By Figure 6 It can be seen that after three cycles of reaction, the activity decreased by only 10.9%, indicating that the catalyst has good stability.
[0043] In Example 12 of this invention, 4 wt% Mo2S before pyrolysis 12 The cyclic hydrogen production performance of / O-C3N4 is shown in the figure below. Figure 7 As shown. By Figure 7 It can be seen that the hydrogen production performance of the catalyst in the first cycle is much worse than that after pyrolysis, and the hydrogen production performance drops rapidly in subsequent cycles. This indicates that the SO bonds generated by in-situ pyrolysis effectively improve the stability of the catalyst, while the amorphization transformation exposes more active sites and improves the hydrogen production performance of the catalyst.
[0044] The α-MoS obtained in Examples 11 to 15 of this invention x The hydrogen production performance of / O-C3N4 is shown in the figure below. Figure 8 As shown. Figure 8 In the diagram, 1 represents the O-C3N4 support, and 2 represents 1 wt% Mo2S before pyrolysis. 12 / O-C3N4, 3 represents 1wt% Mo2S 12 -180 / O-C3N4, where 4 represents 4wt% Mo2S 12 -180 / O-C3N4,5 represents 6wt% Mo2S 12 -180 / O-C3N4, 6 represents 8wt% Mo2S 12 -180 / O-C3N4, 7 represents 10wt% Mo2S12 -180 / O-C3N4. From Figure 8 It can be seen that the load is 1% [Mo2S] 12 ] 2- The hydrogen production activity is significantly improved after the nanoclusters are applied; after pyrolysis, due to [Mo2S] 12 ] 2- The amorphization transformation significantly enhances hydrogen production activity; the composite sample after pyrolysis shows the best activity at a loading of 4 wt%, and further increases in [Mo2S] result in higher activity. 12 ] 2- At certain loading levels, the catalyst activity actually decreases because of the excess [Mo2S] 12 ] 2- It absorbs most of the light and thus creates a masking effect; therefore, the optimal loading is 4%wt.
[0045] The present invention has the following beneficial effects: (1) In-situ pyrolysis [Mo2S] 12 ] 2- Nanoclusters can form SO chemical bonds between the additive and the carbon nitride support, enabling the amorphous molybdenum sulfide generated by pyrolysis to be stably loaded on the carbon nitride support, thereby improving the stability of the photocatalyst.
[0046] (2) In-situ pyrolysis causes [Mo2S] to... 12 ] 2- The transformation of nanoclusters into amorphous molybdenum sulfide exposes more interfacial active sites, allowing more photogenerated electrons to cross the bonding interface and transfer to the cocatalyst, thus reducing recombination and lowering charge transport resistance to accelerate the interfacial proton reduction process, thereby significantly improving the hydrogen production performance of the photocatalyst.
[0047] In summary, this invention is the first to use an impregnation method to [Mo2S] 12 ] 2- Nanoclusters were loaded onto graphitic carbon nitride and [Mo2S] were transferred via in-situ pyrolysis. 12 ] 2- In-situ transformation of nanoclusters into amorphous molybdenum sulfide α-MoS x , a-MoS x It is tightly bonded to graphitic carbon nitride and can be used for photocatalytic hydrogen production, which greatly improves the hydrogen production activity of the photocatalyst and makes the hydrogen evolution performance sufficiently stable.
[0048] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.
Claims
1. A method for preparing an amorphous molybdenum sulfide-supported oxygen-doped graphite-phase carbon nitride catalyst, characterized in that... Follow these steps: The first step is to calcine the required amount of precursor urea to obtain g-C3N4, which is graphitic carbon nitride. The second step is to recalculate g-C3N4 in an oxygen stream to obtain O-C3N4, which is oxygen-doped graphitic carbon nitride. The third step is to synthesize (NH4)2Mo2S. 12 ·2H2O; The fourth step involves impregnating (NH4)2Mo2S with water. 12 ·2H2O loaded on O-C3N4 yields Mo2S 12 / O-C3N4, i.e. [Mo2S 12 ] 2- Nanoclusters loaded with oxygen-doped graphitic carbon nitride; The fifth step involves using in-situ pyrolysis to decompose Mo2S. 12 / O-C3N4 was calcined in an argon gas stream to obtain α-MoS x / O-C3N4 refers to an amorphous molybdenum sulfide-supported oxygen-doped graphite-phase carbon nitride catalyst.
2. The method for preparing the amorphous molybdenum sulfide-supported oxygen-doped graphite-phase carbon nitride catalyst according to claim 1, characterized in that... In the first step, the calcination temperature is 540℃ to 560℃, the heating rate is 5℃ / min, and the holding time is 3.5h to 4.5h.
3. The method for preparing the amorphous molybdenum sulfide-supported oxygen-doped graphite-phase carbon nitride catalyst according to claim 1 or 2, characterized in that... In the second step, the reheating temperature is 540℃ to 560℃, the heating rate is 2℃ / min, and the holding time is 1.5h to 2.5h.
4. The method for preparing an amorphous molybdenum sulfide-supported oxygen-doped graphite-phase carbon nitride catalyst according to any one of claims 1 to 3, characterized in that... In the third step, (NH4)2Mo2S 12 The synthesis of 2H2O is carried out according to the following steps: S1, 30 mL of (NH4)2S was mixed with 7.1 g of sulfur powder and stirred at 50 °C for 15 min to obtain (NH4)2S. x Solution; S2, 2g of ammonium molybdate tetrahydrate and 1.5g of hydroxylamine hydrochloride were mixed to prepare the first mixture; S3, mix 30 mL of the first mixture with (NH4)2S x The solutions were mixed and stirred at 50°C for 2 hours. After filtration, the filtrate was obtained. S4, the filtrate was stirred at 90℃ for 4 hours and cooled to room temperature, and then mixed with 20 mL of (NH4)2S and 6 g of sulfur powder to obtain the second mixture; S5, the second mixture was stirred in an argon atmosphere for 12 hours, filtered, washed sequentially with a low-temperature detergent and centrifuged, and then vacuum dried for 12 hours to obtain (NH4)2Mo2S. 12 ·2H2O.
5. The method for preparing the amorphous molybdenum sulfide-supported oxygen-doped graphite-phase carbon nitride catalyst according to claim 4, characterized in that... In step S5, the low-temperature detergent is deionized water, ethanol, carbon disulfide, and diethyl ether at 4°C.
6. The method for preparing an amorphous molybdenum sulfide-supported oxygen-doped graphite-phase carbon nitride catalyst according to any one of claims 1 to 5, characterized in that... In the fourth step, the specific process of impregnation is as follows: (NH4)2Mo2S 12 ·2H2O was dissolved in methanol, O-C3N4 was added, and the mixture was ultrasonically dispersed for 30 min, then magnetically stirred for 4 h, and centrifuged and vacuum dried for 12 h to obtain Mo2S. 12 / O-C3N4.
7. The method for preparing the amorphous molybdenum sulfide-supported oxygen-doped graphite-phase carbon nitride catalyst according to claim 6, characterized in that... (NH4)2Mo2S 12 The impregnation mass fraction of 2H2O is 1% to 10%.
8. The method for preparing an amorphous molybdenum sulfide-supported oxygen-doped graphite-phase carbon nitride catalyst according to any one of claims 1 to 7, characterized in that... In the fifth step, the calcination temperature is 180℃, the calcination time is 2h, and the heating rate is 2℃ / min.
9. An amorphous molybdenum sulfide-supported oxygen-doped graphite-phase carbon nitride catalyst obtained by the preparation method according to any one of claims 1 to 8.
10. The application of the amorphous molybdenum sulfide supported oxygen-doped graphite phase carbon nitride catalyst according to claim 9 in photocatalytic hydrogen production.