Benzylamine lead iodide / molybdenum disulfide photocatalyst, preparation method and application thereof, and photocatalytic overall water splitting method

Abstract

The application belongs to the technical field of photocatalysis, and particularly relates to a benzylamine lead iodine / molybdenum disulfide photocatalyst, a preparation method and application thereof, and a photocatalytic overall water splitting method. The preparation method comprises the following steps: mixing benzylamine and hydroiodic acid, and evaporating a solvent to obtain PMAI; dissolving lead iodide in hydroiodic acid, adding PMAI, crystallizing after heating and keeping warm, cooling, and separating to obtain PMA2PbI4 and a PMA2PbI4 saturated solution; soaking MoS2 powder in a n-butyl lithium solution, separating and washing a precipitate, and ultrasonically peeling to obtain MoS2 nanosheets; adding PMA2PbI4 and the MoS2 nanosheets to the PMA2PbI4 saturated solution, reacting after heating, cooling, and collecting a precipitate to obtain the benzylamine lead iodine / molybdenum disulfide photocatalyst. The benzylamine lead iodine / molybdenum disulfide photocatalyst can stably produce hydrogen in a dilute HI solution and has excellent activity, and can be placed in the same reaction system with an oxygen production catalyst to realize photocatalytic overall water splitting.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of photocatalysis, and particularly relates to a benzylamine lead iodine / molybdenum disulfide photocatalyst, a preparation method and application thereof, and a photocatalytic overall water splitting method. BACKGROUND

[0002] The information disclosed in this Background section is only for the purpose of increasing an understanding of the general background of the application and does not necessarily constitute an admission or a recognition that the information forms part of the prior art that is already known in any country in the world.

[0003] Photocatalytic splitting of water to produce hydrogen (H2) and oxygen (O2) using solar energy is considered as an ideal way to produce clean energy. However, photocatalytic water splitting still faces considerable challenges, and the solar-to-hydrogen conversion efficiency (STH) is difficult to meet the needs of commercial applications. On the one hand, the commonly used semiconductor photocatalysts have limited light absorption and serious carrier recombination; on the other hand, water splitting faces a high thermodynamic energy barrier (237 kJ mol -1 ) and a slow kinetic oxidation process. Despite the fact that a lot of efforts have been devoted to solving the above problems, it is still a great challenge to obtain a satisfactory STH.

[0004] In recent years, the splitting of hydrogen iodide (HI) to produce H2 by halide perovskite photocatalysts has attracted more and more attention. Although perovskites have made remarkable achievements in photocatalytic splitting of HI to produce hydrogen, the continuous generation of I3 - in this system seriously interferes with the light absorption of the catalyst. In addition, hypophosphorous acid (H3PO2) as an indispensable reducing agent for I3 - , inevitably brings chemical energy, high cost and test uncertainty, and there is currently no ideal method to replace H3PO2 in the HI splitting system. It is well known that the I3 - / I - redox pair is commonly used to construct a Z-type heterojunction photocatalytic water splitting system, so it is considered an ideal method to realize overall water splitting of halide perovskite photocatalysts by using the I3 - / I - redox pair existing in the HI splitting system. However, due to the instability of perovskite materials to water and the strong hydrogen bond between water molecules in strong hydroiodic acid solution, which inhibits the splitting of water, the existing technology for realizing high-efficiency photocatalytic overall water splitting of perovskite materials relies on splitting the hydrogen production reaction and the oxygen production reaction into two reaction systems, and realizing overall water splitting through the circulation of the reaction liquid between the reaction systems. In the above reaction system, the perovskite still produces hydrogen in the conventional HI splitting system, and the circulation process of the reaction liquid will cause loss of the reaction liquid and reduce the reaction efficiency. SUMMARY

[0005] In order to solve the problems of the prior art, the benzylamine lead iodine / molybdenum disulfide photocatalyst, the preparation method and application thereof, and the photocatalytic overall water splitting method are provided. The benzylamine lead iodine / molybdenum disulfide (PMA2PbI4 / MoS2) photocatalyst has high carrier transport and excellent water stability, can stably produce hydrogen in a dilute HI solution and has excellent activity, and can be placed in the same reaction system with a photocatalytic oxygen production catalyst to realize photocatalytic overall water splitting.

[0006] In order to achieve the above-mentioned purpose, the present application is realized by the following technical scheme:

[0007] In the first aspect, a preparation method of a benzylamine lead iodine / molybdenum disulfide photocatalyst comprises the following steps:

[0008] S1, benzylamine and hydroiodic acid are mixed in an ice water bath, and then the solvent is evaporated to obtain PMAI;

[0009] S2, lead iodide is dissolved in hydroiodic acid, then PMAI is added, and the mixture is heated and kept for crystallization to dynamic equilibrium, and then cooled to room temperature, and centrifuged to obtain PMA2PbI4 and a saturated solution of PMA2PbI4;

[0010] S3, MoS2 powder is soaked in a n-butyllithium solution, the precipitate is separated and washed, and the precipitate is ultrasonically stripped to obtain MoS2 nanosheets;

[0011] S4, PMA2PbI4 and MoS2 nanosheets are added to the saturated solution of PMA2PbI4, the mixture is heated and reacted, and then the precipitate is collected after cooling to obtain the benzylamine lead iodine / molybdenum disulfide photocatalyst.

[0012] Preferably, in step S1, the mass concentration of HI in the hydroiodic acid is 46% to 48%, the volume ratio of benzylamine to hydroiodic acid is (2 to 2.5):1, the evaporation temperature is 60 to 80 DEG C, and the evaporation mode includes rotary evaporation.

[0013] Preferably, in step S2, the molar ratio of PMAI to lead iodide is (1.95 to 2.05):1, the molar concentration of lead iodide dissolved in hydroiodic acid is 0.4 to 0.6 mol / L, and the mixture is heated to 94 to 96 DEG C and kept for 0.9 to 1.1 h.

[0014] Preferably, in step S3, the ratio of MoS2 powder to n-butyllithium solution is (1 g):(50 to 75 mL), the concentration of the n-butyllithium solution is 2 to 3 M, and the ultrasonic stripping time is 12 to 15 h.

[0015] Preferably, in step S4, the mass ratio of PMA2PbI4 to MoS2 nanosheets is 100:(1 to 5), the mixture is heated to 95 to 105 DEG C and reacted for 0.5 to 1.5 h.

[0016] In a second aspect, a benzylamine lead iodide / molybdenum disulfide photocatalyst is obtained by the preparation method of the first aspect.

[0017] In a third aspect, the benzylamine lead iodide / molybdenum disulfide photocatalyst of the second aspect is applied in photocatalytic splitting of HI to produce hydrogen and / or photocatalytic overall water splitting.

[0018] In a fourth aspect, a method for photocatalytic overall water splitting comprises the following steps:

[0019] The benzylamine lead iodide / molybdenum disulfide photocatalyst, the photocatalytic oxygen production catalyst and PMAI of the second aspect are added into a HI solution or water to construct a reaction system, and the reaction system is subjected to vacuumization and then light irradiation to perform photocatalytic overall water splitting.

[0020] Preferably, the photocatalytic oxygen production catalyst is WO3 / RuO x , and a preparation method thereof comprises the following steps:

[0021] WO3 is dispersed in an ethanol aqueous solution under continuous stirring under argon protection to form a suspension, a solution of ruthenium trichloride hydrate is added into the suspension, and then light deposition is performed to obtain WO3 / RuO x .

[0022] Further preferably, the mass ratio of WO3 to ruthenium trichloride hydrate is 100:(2.5-3), and the light deposition time is 4-5 h.

[0023] The one or more technical solutions of the present application have the following beneficial effects:

[0024] The benzylamine lead iodide / molybdenum disulfide catalyst has high carrier transport and excellent water stability, can stably produce hydrogen in a dilute HI solution, and has excellent activity.

[0025] I - / I3 - The photocatalytic water splitting system bridged by the redox pair reduces the reaction potential barrier of the hydrogen production and oxygen production reactions. The direct pure water splitting (ΔG θ = 273 kJ mol -1 ) with a large uphill energy is divided into two steps with a thermodynamic advantage, i.e. i) reduction of H + to produce H2 and oxidation of I - to I3 - (ΔG θ = 103 kJ mol -1 ), and ii) oxidation of water to produce O2 and reduction of I3 - to I - (ΔG θ = 170 kJ mol -1). This water splitting system utilizes a detour route, reduces the uphill potential energy of the entire reaction, and overcomes the problem that single-bandgap narrow photocatalysts cannot achieve water splitting.

[0026] Benefiting from the high carrier transport and excellent water stability of the benzylamine lead iodide / molybdenum disulfide catalyst, it can produce H2 / O2 with a molar ratio of 2:1 in a single dilute HI solution reaction system, and obtain an STH of 2.07%, which is higher than most of the currently reported overall water splitting systems. x Benefiting from the high carrier transport and excellent water stability of the benzylamine lead iodide / molybdenum disulfide catalyst, it can produce H2 / O2 with a molar ratio of 2:1 in a single dilute HI solution reaction system, and obtain an STH of 2.07%, which is higher than most of the currently reported overall water splitting systems. BRIEF DESCRIPTION OF DRAWINGS

[0027] The drawings constituting a part of the specification of the present application serve to provide a further understanding of the present application, and the illustrative embodiments of the present application and their description serve to explain the present application, and do not constitute an improper limitation on the present application.

[0028] Figure 1 SEM image of PMA2PbI4 in Example 1, b is a partial enlargement of a;

[0029] Figure 2 TEM image of MoS2 in Example 1, b is a partial enlargement of a;

[0030] Figure 3 SEM image of PMA2PbI4 / MoS2 in Example 1;

[0031] Figure 4 XRD spectrum of PMA2PbI4 and PMA2PbI4 / MoS2 photocatalysts in Example 1;

[0032] Figure 5 Comparison of photocatalytic splitting HI activity of PMA2PbI4 and PMA2PbI4 / MoS2 photocatalysts in different concentrations of HI solution and pure water in Example 1;

[0033] Figure 6 Single particle fluorescence spectrum of (a) PMA2PbI4 and (b) PMA2PbI4 / MoS2 photocatalysts in Example 1, and (c) single particle fluorescence intensity and (d) single particle fluorescence lifetime of PMA2PbI4 and PMA2PbI4 / MoS2 photocatalysts;

[0034] Figure 7 TEM image of WO3 / RuO x in Example 2, b is a partial enlargement of a;

[0035] Figure 8 XRD spectrum of WO3 / RuO x in Example 2;

[0036] Figure 9 For example, (a) WO3 and (b) WO3 / RuO in Example 2 x Single-particle fluorescence spectra and WO3 and WO3 / RuO x (c) Single-particle fluorescence intensity and (d) Single-particle fluorescence lifetime of the photocatalyst;

[0037] Figure 10 The PMA2PbI4 / MoS2 photocatalyst in Example 1 and the WO3 / RuO2 photocatalyst in Example 2 x A schematic diagram of the band structure;

[0038] Figure 11 The PMA2PbI4 / MoS2 photocatalyst and WO3 / RuO2 in Example 2 x Photocatalytic water splitting activity diagrams in HI solutions of different concentrations and in pure water. Detailed Implementation

[0039] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments and comparative examples.

[0040] Example 1

[0041] 25 mL of benzylamine (99%) and 10 mL of hydroiodic acid (47% HI, aqueous solution) were mixed and stirred in an ice-water bath for 2 h. The solvent was removed by rotary evaporation at 80 °C. The crude product was washed three times with diethyl ether, and the resulting PMAI white powder was dried in a vacuum oven at 65 °C for 20 h. 2.31 g of PbI₂ (5 mmol) was dissolved in 10 mL of hydroiodic acid (47% HI, aqueous solution), and then 2.33 g of PMAI (10 mmol) was added with vigorous stirring. The solution was heated to 95 °C and held for 1 h to reach dynamic equilibrium, and then cooled to room temperature to obtain PMA₂PbI₄ and its saturated solution.

[0042] like Figure 1 As shown, PMA2PbI4 has a smooth two-dimensional planar structure with a thickness of approximately 5 μm.

[0043] 0.5 g of bulk MoS2 powder was immersed in 25 mL of n-butyllithium solution (2.5 M hexane solution) and soaked in a bottle containing Ar gas for 3 days. Then, Li was recovered by filtration. x MoS2 was used, and the mixture was washed with hexane to remove excess Li and organic residues. Li was then subjected to ultrasonic treatment in water. x MoS2 was ultrasonically exfoliated for 12 hours. The resulting black precipitate was washed sequentially with acetone, ethanol, and water. Finally, the black precipitate was freeze-dried to obtain MoS2 nanosheets.

[0044] like Figure 2 As shown, MoS2 consists of ultrathin nanosheets of a few micrometers.

[0045] 100 mg of synthesized PMA2PbI4 powder and 5 mg of MoS2 nanosheets were added to 30 mL of saturated PMA2PbI4 solution, heated to 100 °C and held for 1 h, then cooled to room temperature. The resulting benzylamine lead iodide / molybdenum disulfide (PMA2PbI4 / MoS2) photocatalyst was thus obtained.

[0046] like Figure 3 As shown, MoS2 nanosheets are uniformly distributed on the surface of PMA2PbI4 in the PMA2PbI4 / MoS2 photocatalyst.

[0047] like Figure 4 As shown, PMA2PbI4 exhibits good crystallinity, and no XRD peak of MoS2 was observed in the XRD pattern of the PMA2PbI4 / MoS2 photocatalyst. This is due to the low loading and weak crystallinity of MoS2.

[0048] The photocatalytic reaction was carried out in a Pyrex reactor connected to a closed gas circulation and vacuum system. 500 mg of PMA₂PbI₄ / MoS₂ photocatalyst or PMA₂PbI₄ was added to 30 mL of diluted HI solution, with PMAI added as a perovskite stabilizer (I₂ in the solution). - Ion concentration higher than 2.5 mol L -1 The system was evacuated for 30 minutes to ensure complete removal of air, and then irradiated from the top surface using a 300W xenon lamp (PLS-SXE300D, Beijing Perfect Light Technology Co., Ltd.) equipped with an AM1.5G filter. The reaction suspension was maintained at 298K using a cooling water stream. The separated gases were analyzed by gas chromatography (GC-7290, TCD, with Ar as the carrier gas). Figure 5 As shown, the PMA2PbI4 / MoS2 photocatalyst exhibits excellent activity in HI solutions of different concentrations, with hydrogen production performance approximately 6 times that of PMA2PbI4.

[0049] like Figure 6 As shown, compared with PMA2PbI4, the quenching, reduced PL intensity, and shortened PL lifetime of the PMA2PbI4 / MoS2 photocatalyst in single-particle PL images indicate that the loading of MoS2 promotes charge transport and inhibits charge carrier recombination.

[0050] Example 2

[0051] WO3 / RuO was prepared by photo-assisted selective deposition. xSpecifically, 0.1 g WO3 was dispersed in 20 mL of ethanol solution and then stirred continuously for 30 minutes under Ar protection at 40 °C. Then, 1 mL of ruthenium trichloride hydrate solution (3 mg / mL) was added. -1 The WO3 / RuO2 was slowly injected into the suspension and stirred for 2 hours. Then, the reaction system was irradiated with an Xe lamp fitted with an AM1.5G filter for 4 hours. Afterwards, the resulting WO3 / RuO2 was... x Wash several times with ethanol and dry at 60°C.

[0052] like Figure 7 As shown, the size of WO3 particles is approximately 20 nm, and the WO3 / RuO3 structure is constructed. x After composite material processing, RuO with a size of 5-7 nm x The nanoparticles were anchored on WO3. In addition, two different lattice fringes corresponding to WO3 (0.25 nm, (220) plane) and RuO2 (0.32 nm, (110) plane) were observed.

[0053] like Figure 8 As shown, WO3 and WO3 / RuO x The XRD pattern corresponds to the WO3 standard pattern (PDF#71-305).

[0054] like Figure 9 As shown, compared with WO3, WO3 / RuO x Quenching, decreased PL intensity, and shortened PL lifetime in single-particle PL images indicate that RuO x The load promotes charge transport and suppresses recombination of charge carriers.

[0055] The photocatalytic reaction was carried out in a Pyrex reactor connected to a closed gas circulation and vacuum system. 100 mg of the PMA2PbI4 / MoS2 photocatalyst from Example 1 and 300 mg of WO3 / RuO2 were used. x Add to 30 mL of diluted HI solution, to which PMAI is added as a perovskite stabilizer (I in the solution). - Ion concentration higher than 2.5 mol L -1 The system was evacuated for 30 minutes to ensure complete removal of air, and then irradiated from the top surface using a 300W xenon lamp (PLS-SXE300D, Beijing Perfect Light Technology Co., Ltd.) equipped with an AM1.5G filter. The reaction suspension was maintained at 298K using a cooling water stream. The separated gases were analyzed by gas chromatography (GC-7290, TCD, with Ar as the carrier gas).

[0056] like Figure 10The band positions of the synthesized PMA2PbI4 / MoS2 photocatalyst match the HI decomposition, WO3 / RuO x The band positions of the synthesized PMA2PbI4 / MoS2 photocatalyst match the HI decomposition, WO3 / RuO - The band positions of the synthesized PMA2PbI4 / MoS2 photocatalyst match the HI decomposition, WO3 / RuO - The band positions of the synthesized PMA2PbI4 / MoS2 photocatalyst match the HI decomposition, WO3 / RuO - The band positions of the synthesized PMA2PbI4 / MoS2 photocatalyst match the HI decomposition, WO3 / RuO

[0057] As shown in FIG. 1, the band positions of the synthesized PMA2PbI4 / MoS2 photocatalyst match the HI decomposition, WO3 / RuO Figure 11 As shown in FIG. 1, the band positions of the synthesized PMA2PbI4 / MoS2 photocatalyst match the HI decomposition, WO3 / RuO -1 As shown in FIG. 1, the band positions of the synthesized PMA2PbI4 / MoS2 photocatalyst match the HI decomposition, WO3 / RuO

[0058] Example 3

[0059] The band positions of the synthesized PMA2PbI4 / MoS2 photocatalyst match the HI decomposition, WO3 / RuO

[0060] The band positions of the synthesized PMA2PbI4 / MoS2 photocatalyst match the HI decomposition, WO3 / RuO x The band positions of the synthesized PMA2PbI4 / MoS2 photocatalyst match the HI decomposition, WO3 / RuO x The band positions of the synthesized PMA2PbI4 / MoS2 photocatalyst match the HI decomposition, WO3 / RuO

[0061] The band positions of the synthesized PMA2PbI4 / MoS2 photocatalyst match the HI decomposition, WO3 / RuO

[0062] Example 4

[0063] benzylamine (99%) and 10 mL of hydriodic acid (HI mass concentration 47%, aqueous solution) were mixed and stirred for 2 h under an ice-water bath. The solvent was removed by rotary evaporation at 80 °C. The crude product was washed with diethyl ether for 3 times, and the final PMAI white powder was dried in a vacuum oven at 65 °C for 20 h. 2.31 g of PbI2(5 mmol) was dissolved in 10 mL of hydriodic acid (HI mass concentration 47%, aqueous solution), and then 2.39 g of PMAI (10.25 mmol) was added under vigorous stirring. The solution was heated to 96 °C for 0.9 h to reach dynamic equilibrium, and then cooled to room temperature to obtain PMA2PbI4and its saturated solution.

[0064] 0.5 g of bulk MoS2powder was immersed in 37.5 mL of n-butyllithium solution (3 M in hexane) for 3 days in a bottle filled with Ar gas. Then, Li x MoS2was recovered by filtration and washed with hexane to remove excess Li and organic residues. Ultrasonic exfoliation was performed by ultrasonic treatment of Li x MoS2in water for 12 h. The black precipitate after exfoliation was washed with acetone, ethanol and water in turn. Finally, MoS2nanosheets were obtained by freeze-drying the black precipitate.

[0065] 100 mg of synthesized PMA2PbI4powder and 5 mg of MoS2nanosheets were added to 30 mL of PMA2PbI4saturated solution, heated to 105 °C for 0.5 h, and cooled to room temperature. Finally, the benzylamine lead iodide / molybdenum disulfide (PMA2PbI4 / MoS2) photocatalyst was obtained.

[0066] The preferred embodiments of the present application have been described above with the purpose of not limiting the present application, and various modifications and changes can be made by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a benzylamine lead iodine / molybdenum disulfide photocatalyst, characterized in that, Includes the following steps: S1, benzylamine and hydroiodic acid were mixed in an ice-water bath and the solvent was evaporated to obtain PMAI; S2. Dissolve lead iodide in hydroiodic acid, add PMAI, heat and keep warm to crystallize to dynamic equilibrium, cool to room temperature, and centrifuge to obtain PMA2PbI4 and saturated PMA2PbI4 solution. S3. MoS2 powder is added to n-butyllithium solution for soaking, the precipitate is separated and washed, and the precipitate is obtained by ultrasonic exfoliation to obtain MoS2 nanosheets. S4. PMA2PbI4 and MoS2 nanosheets were added to a saturated solution of PMA2PbI4, heated to react, cooled and collected the precipitate to obtain benzylamine lead iodide / molybdenum disulfide photocatalyst.

2. The preparation method according to claim 1, characterized in that, In step S1, the mass concentration of HI in hydroiodic acid is 46% to 48%, the volume ratio of benzylamine to hydroiodic acid is (2 to 2.5):1, the evaporation temperature is 60 to 80°C, and the evaporation method includes rotary evaporation.

3. The preparation method according to claim 1, characterized in that, In step S2, the molar ratio of PMAI to lead iodide is (1.95–2.05):1, the molar concentration of lead iodide dissolved in hydroiodic acid is 0.4–0.6 mol / L, and the mixture is heated to 94–96 °C and kept at that temperature for 0.9–1.1 h.

4. The preparation method according to claim 1, characterized in that, In step S3, the ratio of MoS2 powder to n-butyllithium solution is (1g):(50-75mL), the concentration of n-butyllithium solution is 2-3M, and the ultrasonic exfoliation time is 12-15h.

5. The preparation method according to claim 1, characterized in that, In step S4, the mass ratio of PMA2PbI4 to MoS2 nanosheets is 100:(1-5), and the reaction is carried out at 95-105℃ for 0.5-1.5 h.

6. A benzylamine lead iodine / molybdenum disulfide photocatalyst, characterized in that, Obtained by the preparation method described in any one of claims 1 to 5.

7. The application of the benzylamine lead iodine / molybdenum disulfide photocatalyst as described in claim 6 in photocatalytic cracking of HI to produce hydrogen and / or photocatalytic total water splitting.

8. A photocatalytic method for total water splitting, characterized in that, Includes the following steps: The benzylamine lead iodine / molybdenum disulfide photocatalyst, the photocatalytic oxygen production catalyst, and PMAI as described in claim 6 are added to HI solution or water to construct a reaction system. After the reaction system is evacuated, light is applied to perform photocatalytic total water splitting.

9. The photocatalytic total water splitting method as described in claim 8, characterized in that, The photocatalytic oxygen production catalyst is WO3 / RuO x The preparation method includes the following steps: WO3 was dispersed in an aqueous ethanol solution and continuously stirred under argon protection to form a suspension. A solution of ruthenium trichloride hydrate was added to the suspension, followed by photodeposition under illumination to obtain WO3 / RuO2. x .

10. The photocatalytic total water splitting method as described in claim 9, characterized in that, The mass ratio of WO3 to ruthenium trichloride hydrate was 100:(2.5-3), and the photodeposition time was 4-5 h.

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