A Zn-coordinated sulfur interstitial Zn x Cd 1-x Preparation methods and applications of S crystal materials

Abstract

This invention discloses a Zn-coordinated sulfur interstitial Zn x Cd 1‑x Preparation method and application of S crystal materials. This invention is the first to use alkaline ammonia gas to prepare Zn crystal materials. x Cd 1‑x In S crystal materials, sulfur interstitial material is selectively coordinated around Zn to obtain Zn-site coordinated sulfur interstitial material. x Cd 1‑x S crystal material. Zn prepared according to this invention. x Cd 1‑x S-crystal materials, due to their unique coordination structure and composition, possess highly efficient reactivity and can serve as efficient photocatalysts for hydrogen production. The preparation method of this invention is simple, controllable, low-cost, and uses readily available raw materials, making it suitable for large-scale production.

Description

A Zn-coordinated sulfur interstitial Zn x Cd 1-x Preparation methods and applications of S crystal materials Technical Field

[0001] This invention belongs to the field of materials preparation technology and relates to a Zn-coordinated sulfur interstitial Zn. x Cd 1-x Preparation methods and applications of S crystal materials. Background Technology

[0002] Sulfur interstitials are sulfur elements coordinated with metals introduced into the sulfide lattice. The development of sulfur interstitials holds significant potential in catalysis applications; however, their introduction into transition metal sulfides is severely limited due to the high chemical bond energy between sulfur interstitials and surrounding coordinating elements. The introduction of sulfur interstitials affects the electronic structure of materials, thereby altering their physicochemical properties and presenting enormous application prospects in energy storage, catalysis, and environmental protection. However, the complexity and difficulty in industrial application of currently developed sulfur interstitial introduction methods severely hinder their large-scale production. Therefore, an effective method for introducing sulfur interstitials into transition metal sulfides is urgently needed.

[0003] The introduction of sulfur interstitials plays a crucial role in photocatalytic applications. In current photocatalytic applications, the adsorption energy of interfacial water molecules is influenced by the material's coordination. However, controlling the coordination position of incorporated non-metallic elements based on metal or non-metal substitution or doping strategies is difficult, and the random incorporation of sulfur interstitials limits the potential for improving photocatalytic performance. Therefore, researching effective methods for precisely controlling the coordination position of incorporated sulfur elements and developing novel sulfide materials is urgent and important.

[0004] Transition metal sulfides exhibit significant visible light response, are inexpensive, and possess impressive photocatalytic hydrogen production performance, making them potential future photocatalytic hydrogen production materials. Among these, Zn is obtained through a hydrothermal reaction. x Cd 1-x S is a photocatalytic material with high photocatalytic hydrogen production, but precise control of Zn in the one-step regulation process is crucial. x Cd 1-x There is a lack of methods for determining the coordination ratio of sulfur interstitial material around Zn in S. At the same time, improving the performance of photocatalysts through sulfur interstitial material is one of the hot topics in photocatalysis research. Summary of the Invention

[0005] In view of the problems existing in the prior art, the object of the present invention is to provide a Zn-coordinated sulfur interstitial Zn x Cd 1-x Preparation methods and applications of S crystal materials, precise control of Zn x Cd1-x The proportion of sulfur interstitial material in S coordinated around Zn.

[0006] To achieve the above-mentioned technical objectives, the present invention provides the following technical solution:

[0007] The present invention provides a Zn-coordinated sulfur interstitial Zn x Cd 1-x The preparation method of S (where 0 < x < 1) crystal material includes the following steps: adding zinc acetate dihydrate and cadmium nitrate tetrahydrate to an aqueous solution of ethylenediamine, then adding thiourea, stirring thoroughly to obtain a mixture, reacting the mixture under high pressure and constant pressure conditions, introducing alkaline ammonia gas during the reaction, maintaining constant pressure until the reaction is completed, cooling to room temperature, filtering, washing and drying to obtain Zn coordinated sulfur interstitial Zn. x Cd 1-x S-crystal materials.

[0008] Preferably, the molar ratio of Zn(CH3COO)2·2H2O to Cd(NO3)2·4H2O is (1~10):1.

[0009] Preferably, the aqueous solution of ethylenediamine has a mass concentration of 30% to 90%.

[0010] Preferably, the molar ratio of Cd(NO3)2·4H2O to thiourea is (0.01~0.05):1.

[0011] Preferably, the alkaline ammonia gas is at least one of ethylamine, methylamine, dimethylamine, trimethylamine, and ammonia.

[0012] Preferably, the molar ratio of the alkaline ammonia gas to ethylenediamine is (0.03-1.0):1.0.

[0013] Preferably, the stirring time is 0.5 to 2 hours.

[0014] Preferably, the reaction temperature is 90–200°C, the reaction time is 1–40 h, and the high-pressure constant pressure is 0.2–0.4 MPa.

[0015] Preferably, the mixture is reacted under high pressure and constant pressure conditions for 2 to 10 hours before the alkaline ammonia gas is introduced, and the constant pressure is maintained until the reaction is completed.

[0016] Zn-coordinated sulfur interstitium prepared according to the above method x Cd 1-x S-crystal materials.

[0017] The Zn coordinated with the sulfur interstitium x Cd 1-xS-crystalline material, in which sulfur interstitial elements are coordinated around Zn; the Zn coordinated with the sulfur interstitial elements is Zn x Cd 1-x S-crystal material, which has the morphology of nanorods with a size of 50-200 nm in length and 5-10 nm in width.

[0018] The Zn coordinated with the sulfur interstitium x Cd 1-x Application of S crystal materials as photocatalysts in photocatalysis.

[0019] In this invention, when alkaline ammonia gas is introduced, Zn ions react more readily with amine organic groups formed in the system than Cd ions. This leads to the adsorption of sulfur-containing organic compounds at Zn sites, leaving sites for S to combine with other organic sulfur compounds. Ultimately, this causes the accumulation of sulfur interstitial material around Zn ions, forming Zn-coordinated sulfur interstitial material. x Cd 1-x S-crystal materials.

[0020] The beneficial effects of this invention are:

[0021] 1) This invention uses a one-step hydrothermal method to synthesize Zn with different Zn / Cd ratios in Zn-coordinated sulfur interstitial material. x Cd 1-x S crystal material (I S(Zn) -Zn x Cd 1-x S), due to the coordination of sulfur interstitial material at Zn sites, the hydrogen production performance of the catalyst in visible light photocatalytic hydrogen evolution is greatly improved, and it can maintain high hydrogen production efficiency under visible light and the action of hole scavengers and water.

[0022] 2) This invention is the first to introduce Zn-coordinated sulfur interstitial by introducing alkaline ammonia gas, which can precisely control the ratio of sulfur interstitial to Zn coordination. Furthermore, the preparation method of this invention is scientific, simple, reasonable, easy to implement, and low in cost, making it suitable for large-scale production. Attached Figure Description

[0023] Figure 1 shows the I in Example 1. S(Zn) -Zn x Cd 1-x Elemental Zn / Cd ratio analysis diagram of S crystal material.

[0024] Figure 2 shows the I in Example 1. S(Zn) -Zn x Cd 1-x S elemental analysis diagram of S crystal material.

[0025] Figure 3 shows the I in Example 1. S(Zn) -Zn 0.8 Cd 0.2Zn-S coordination K-side Fourier transform EXAFS diagram of S crystal material.

[0026] Figure 4 shows the I in Example 1. S(Zn) -Zn 0.8 Cd 0.2 Cd-S coordination K-side Fourier transform EXAFS diagram of S crystal material.

[0027] Figure 5 shows the I in Example 1. S(Zn) -Zn 0.8 Cd 0.2 XRD pattern of S crystal material.

[0028] Figure 6 shows the I in Example 1. S(Zn) -Zn 0.8 Cd 0.2 SEM image of S crystal material.

[0029] Figure 7 shows the I in Example 1. S(Zn) -Zn x Cd 1-x Photocatalytic hydrogen production performance of S crystal material. Detailed Implementation

[0030] To make the above-mentioned objectives, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to examples.

[0031] Example 1

[0032] Zn with different Zn / Cd ratios for preparing Zn-coordinated sulfur interstitial media x Cd 1-x S nanocrystalline materials (I S(Zn) -Zn x Cd 1-x S):

[0033] 1)I S(Zn) -Zn 0.9 Cd 0.1 Preparation of S crystal materials

[0034] 30 mL of water and 15 mL of ethylenediamine were placed in a beaker, and 0.45 mmol of Zn(CH3COO)2·2H2O and 0.05 mmol of Cd(NO3)2·4H2O were added. The mixture was stirred for 10 min to obtain a uniformly distributed ionic liquid. 1.3 mmol of CH4N2S was added to the above solution, and the mixture was stirred continuously at 500 r / min for 30 min to obtain a mixed solution. The mixed solution was transferred to a 300 mL high-pressure constant-pressure reactor and heated. After maintaining the temperature at 150 °C for 8 h at a constant pressure of 0.2 MPa, a mixed gas of 0.025 mol of ammonia and methylamine was introduced at a constant flow rate, with a molar ratio of ammonia to methylamine of 1:1. The temperature was maintained for 24 h. After the reaction was completed, the product was removed, cooled, filtered, and repeatedly washed with ethanol and deionized water. Finally, the washed product was dried in a vacuum drying oven at 60 °C for 48 h to obtain I. S(Zn) -Zn 0.9 Cd 0.1 S-crystal materials.

[0035] 2)I S(Zn) -Zn 0.8 Cd 0.2 Preparation of S crystal materials

[0036] 30 mL of water and 20 mL of ethylenediamine were placed in a beaker, and 0.40 mmol of Zn(CH3COO)2·2H2O and 0.10 mmol of Cd(NO3)2·4H2O were added. The mixture was stirred for 10 min to obtain a uniformly distributed ionic liquid. 3 mmol of CH4N2S was added to the above solution, and the mixture was stirred continuously at 500 r / min for 30 min to obtain a mixture. The mixture was transferred to a 300 mL high-pressure constant-pressure reactor and heated. After maintaining the temperature at 140 °C for 7 h at a constant pressure of 0.25 MPa, 0.09 mol of methylamine gas was introduced at a constant flow rate, and the temperature was maintained for 24 h until the reaction was complete. The mixture was then removed, cooled, and filtered. It was repeatedly washed with ethanol and deionized water. Finally, the washed product was dried in a vacuum drying oven at 80 °C for 24 h to obtain I. S(Zn) -Zn 0.8 Cd 0.2 S-crystal materials.

[0037] 3)I S(Zn) -Zn 0.7 Cd 0.3 Preparation of S crystal materials

[0038] 30 mL of water and 25 mL of ethylenediamine were placed in a beaker, and 0.35 mmol of Zn(CH3COO)2·2H2O and 0.15 mmol of Cd(NO3)2·4H2O were added. The mixture was stirred at 500 rpm for 10 min to obtain a uniformly distributed ionic liquid. 6 mmol of CH4N2S was added to the above solution, and the mixture was stirred at 500 rpm for 30 min to obtain a mixed solution. The mixed solution was transferred to a 300 mL high-pressure constant-pressure reactor and heated. After maintaining the temperature at 0.3 MPa and 160 °C for 10 h, a mixture of 0.075 mol of dimethylamine and ethylamine (molar ratio of dimethylamine to ethylamine 1:1) was introduced at a constant flow rate, and the reaction was maintained for 30 h until completion. The product was repeatedly washed with ethanol and deionized water. Finally, the washed product was dried in a vacuum drying oven at 60 °C for 48 h to obtain I. S(Zn) -Zn 0.7 Cd 0.3 S-crystal materials.

[0039] 4)I S(Zn) -Zn 0.6 Cd 0.4 Preparation of S crystal materials

[0040] 30 mL of water and 30 mL of ethylenediamine were placed in a beaker, and 0.30 mmol of Zn(CH3COO)2·2H2O and 0.20 mmol of Cd(NO3)2·4H2O were added. The mixture was stirred for 10 min to obtain a uniformly distributed ionic liquid. 7 mmol of CH4N2S was added to the above solution, and the mixture was stirred continuously for 30 min to obtain a mixed solution. The mixed solution was transferred to a 300 mL high-pressure constant-pressure reactor and heated. After maintaining the temperature at 0.4 MPa and 170 °C for 6 h, a mixture of 0.1 mol of ammonia and trimethylamine gas (molar ratio of ammonia to trimethylamine 1:1) was introduced at a constant flow rate. The reaction was maintained for 30 h until completion. The mixture was then removed, cooled, filtered, and repeatedly washed with ethanol and deionized water. Finally, the washed product was dried in a vacuum drying oven at 60 °C for 48 h to obtain I. S(Zn) -Zn 0.6 Cd 0.4 S-crystal materials.

[0041] Different I obtained in this embodiment S(Zn) -Zn x Cd 1-x The elemental Zn / Cd ratio in the S crystal material was tested and analyzed, and the results are shown in Figure 1. As can be seen from Figure 1, I... S(Zn) -Zn 0.9 Cd 0.1 S, I S(Zn) -Zn 0.8 Cd 0.2 S, IS(Zn) -Zn 0.7 Cd 0.3 S, I S(Zn) -Zn 0.6 Cd 0.4 The Zn / Cd ratio in S is consistent with the Zn / Cd ratio in the corresponding pure ZnCdS.

[0042] The I prepared in this embodiment S(Zn) -Zn x Cd 1-x The sulfur content in the S crystal material was tested and analyzed, and the results are shown in Figure 2. As can be seen from the figure, I... S(Zn) -Zn 0.9 Cd 0.1 S, I S(Zn) -Zn 0.8 Cd 0.2 S, I S(Zn) -Zn 0.7 Cd 0.3 S, I S(Zn) -Zn 0.6 Cd 0.4 The ratio of S / (Zn+Cd+S) in S is greater than 0.5, indicating the presence of sulfur interstitial matter.

[0043] The I prepared in this embodiment S(Zn) -Zn 0.8 Cd 0.2 The results of the Zn-S coordination K-side Fourier transform EXAFS test in the S crystal material are shown in Figure 3. As can be seen from the figure, the coordination number of S around Zn is significantly increased, leading to an enhanced strength of the first coordination Zn-S shell.

[0044] The I prepared in this embodiment S(Zn) -Zn 0.8 Cd 0.2 The results of the Cd-S coordination K-side Fourier transform EXAFS test in the S crystal material are shown in Figure 4. As can be seen from the figure, since the S coordination number around Cd does not change significantly, the strength of the first coordination Cd-S shell of Cd is similar to that of Zn. 0.8 Cd 0.2 The indifference of S.

[0045] The I prepared in this embodiment S(Zn) -Zn x Cd 1-x XRD diffraction analysis was performed on the S crystal material, and its XRD pattern is shown in Figure 5. As can be seen from the figure, I... S(Zn) -Zn 0.8 Cd 0.2 All peaks of S are related to Zn. 0.8 Cd 0.2The fact that the S standard PDF card 35-1469 corresponds to and moves to a lower degree further indicates that sulfur has been successfully incorporated.

[0046] The I prepared in this embodiment S(Zn) -Zn 0.8 Cd 0.2 The S crystal material was subjected to scanning electron microscopy (SEM) testing, and its SEM image is shown in Figure 6. As can be seen from the figure, I... S(Zn) -Zn 0.8 Cd 0.2 S is a rod-shaped nanocrystal with a diameter of 100–200 nm.

[0047] Example 2

[0048] Different I prepared in Example 1 S(Zn) -Zn x Cd 1-x The photocatalytic activity of the S crystal material was tested in a photocatalytic reactor (Labsolar-6A, Beijing Perfect Technology Co., Ltd.). For each experiment, 10.0 mg of I was added to 100 mL of deionized water. S(Zn) -Zn x Cd 1-x S, 0.035 mol sodium sulfide, and 0.025 mol sodium sulfite were ultrasonicated in an ultrasonic bath for 30 min. The solution was stored at 5°C and irradiated with a 300W xenon lamp and a 420nm ultraviolet filter. The hydrogen production was determined by gas chromatography. Different I... S(Zn) -Zn x Cd 1-x The hydrogen production performance of the S crystal material under visible light is shown in Figure 7.

[0049] As can be seen from Figure 7, I S(Zn) -Zn 0.9 Cd 0.1 S, I S(Zn) -Zn 0.8 Cd 0.2 S, I S(Zn) -Zn 0.7 Cd 0.3 S and I S(Zn) -Zn 0.6 Cd 0.4 The hydrogen production performance of S is significantly improved compared to ZnCdS with the corresponding Zn / Cd ratio. S(Zn) -Zn 0.9 Cd 0.1 S material is better than Zn 0.9 Cd 0.1 The hydrogen production performance of S was improved by 5.9 times, from 0.38 mmol·g -1 ·h -1 Increased to 2.23 mmol·g -1 ·h-1 ;I S(Zn) -Zn 0.8 Cd 0.2 S compared to Zn 0.8 Cd 0.2 The hydrogen production performance of S was improved by 5.3 times, from 1.13 mmol·g⁻¹. -1 ·h -1 Increased to 6 mmol·g -1 ·h -1 ;I S(Zn) -Zn 0.7 Cd 0.3 S compared to Zn 0.7 Cd 0.3 The hydrogen production performance of S was improved by 5.4 times, from 1.85 mmol·g -1 ·h -1 Increased to 9.99 mmol·g -1 ·h -1 ;I S(Zn) -Zn 0.6 Cd 0.4 S material is better than Zn 0.6 Cd 0.4 S exhibits a 4.8-fold improvement in hydrogen production performance, from 4.23 mmol·g⁻¹. -1 ·h -1 Increased to 20.12 mmol·g -1 ·h -1 .

[0050] This invention employs a modified one-step hydrothermal method to synthesize Zn with tunable coordination with Zn. x Cd 1-x S crystal material I S(Zn) -Zn x Cd 1-x S, due to the change in the number of S elements coordinated at Zn sites, I S(Zn) -Zn x Cd 1-x S exhibits highly efficient photocatalytic hydrogen production performance in response to visible light and can be applied to the photocatalytic decomposition of water.

Claims

1. A Zn-coordinated sulfur interstitium x Cd 1-x The preparation method of S crystal material includes the following steps: adding zinc acetate dihydrate and cadmium nitrate tetrahydrate to an aqueous solution of ethylenediamine, then adding thiourea, stirring thoroughly to obtain a mixture, reacting the mixture under high pressure and constant pressure conditions, introducing alkaline ammonia gas during the reaction, maintaining constant pressure until the reaction is completed, cooling to room temperature, filtering, washing and drying to obtain Zn coordinated sulfur interstitial Zn. x Cd 1-x S is a crystal material; the molar ratio of Zn(CH3COO)2·2H2O to Cd(NO3)2·4H2O is (1~10):1; the mass concentration of ethylenediamine in the aqueous solution is 30%~90%; the molar ratio of Cd(NO3)2·4H2O to thiourea is (0.01~0.05):1; the molar ratio of alkaline ammonia gas to ethylenediamine is (0.03~1.0):1.0; the reaction temperature is 90~200 ℃, the reaction time is 31~40 h, and the high pressure constant pressure is 0.2~0.4 MPa; the alkaline ammonia gas is introduced after the mixture has reacted under high pressure constant pressure for 2~10 h.

2. The preparation method according to claim 1, characterized in that, The alkaline ammonia gas is at least one of ethylamine, methylamine, dimethylamine, trimethylamine, and ammonia.

3. A Zn-coordinated sulfur interstitium prepared by the preparation method according to claim 1 or 2. x Cd 1-x S-crystal materials.

4. The Zn-coordinated sulfur interstitium according to claim 3 x Cd 1-x S-crystal material, characterized in that... The sulfur interstitium is coordinated around the Zn element; Zn coordinated with the sulfur interstitium x Cd 1-x S crystal material, which has the morphology of nanorods with a size of 50~200 nm in length and 5~10 nm in width.

5. A Zn-coordinated sulfur interstitium according to claim 3 x Cd 1-x Application of S crystal materials as photocatalysts in photocatalysis.

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